In appearance, voice, and mannerisms, this medium-sized cotinga has a character all its own. At the first glimpse of a male Masked Tityra flying overhead, one is likely to exclaim, “A little white bird!” Closer scrutiny of the tityra reveals that his plumage is not so white as it first appears; a formal description of this stout, eight-inch bird fails to give an adequate notion of its whiteness when viewed in flight or as it rests in a treetop. His upper plumage is generally pale bluish-gray, becoming almost white on the hind head, and his under plumage approaches still more closely to white. His wings are largely black.
The tail is pale gray with a broad, black subterminal band and a narrow whitish border across the end. His reddish eyes are surrounded by a broad area of bright red bare skin, which covers the lores. This naked patch is margined all around by black feathers, which form a narrow fringe across the chin and broadband over the forehead. The short, stout bill, of which the upper mandible is terminated by a short, down-curved hook, is red basally and black at the tip. The female tityra is far less white than the male, for her plumage is grayish-brown above and light gray below. The naked skin around her eyes is a paler red than that of the male. The legs and feet of both sexes are dark gray.
The species ranges from northern Mexico to western Ecuador, Bolivia, Brazil, and the Guianas. Over much of this vast area, it is one of the first members of the cotinga family that a visiting naturalist is likely to meet. Tolerant of varied ecological conditions, it lives not only in the most humid rain forests but also in semi-arid regions with scattered trees.
In Central America, it is widespread over the lowlands of both coasts, and it extends far upward into the mountains. On the Pacific side of the Cordillera de Talamanca, I found it in late February nearly 7000 feet above sea level, and on the Cordillera Central in May I saw a wandering male at about 7500 feet, but I doubt whether tityras nest so high. At Vara Blanca on the northern side of the Cordillera Central of Costa Rica, I found it nesting at an altitude of 5.500 feet.
But in this extremely wet region I failed to see a tityra between August and late February, whence I inferred that it performs a slight altitudinal migration, dropping down to lower levels after the close of the nesting season and ascending the mountains again as the following breeding season approaches. Tityras are at home in the tops of the big forest trees, where one hears them far more often than he sees them.
But they often make excursions, in pairs or small flocks, through clearings and plantations with scattered tall trees, and they often nest in dead trees standing isolated near the forest’s edge. Almost always they fly and forage at a good height above the ground. Except while nesting, these restless, wandering birds seldom remain long in one locality.
They appear to be mated throughout the year, for I have often seen pairs even in the autumn months. Yet at all seasons, including that in which they nest, one occasionally meets small, wandering flocks composed largely of males. The latter seems to be considerably more numerous than the females. After pairing, the male tityra is ever a faithful companion of his mate and seems subservient to her will. For example, late one cloudy afternoon in March, I noticed a pair of these birds resting in dead trees in a clearing beside the woodland, where they were preparing to nest. The male, which seemed eager to go to roost in the neighboring forest, flew twice across the clearing to a tree at its edge, where he called and waited for his partner to follow.
Since she was not yet ready to go, he returned each time to await her pleasure. Soon, however, she yielded to his entreaties, and the two flew away over the forest together. Like other cotingas, tityras, while perching, quietly turn their heads from side to side, scrutinizing the surrounding foliage until they detect an edible insect, which they snatch from the leaves by means of a sudden dart, without alighting beside it.
The first tityra that I ever saw held in its bill a fleet-winged dragonfly, but I do not know whether this insect was captured while it was flying or at rest. Tityras also eat berries and other small fruits of trees. tityras went to rest much earlier in the evening and became active far later in the morning than many of the surrounding birds.
Read More - Whistling Kite (Haliastur sphenurus)
Nest Building
The Masked Tityra nearly always nests in cavities in dead or, more rarely, living trees, usually from 40 to 100 feet above the ground. Until quite recently, the lowest hole into which I had seen a tityra carry material was 20 feet up in a slender stub standing in a clearing, but apparently, she did not lay there. In 1964, however, a tityra built a nest in an old woodpecker hole only 13 feet up in the top of a small, dead avocado tree in a coffee plantation on our farm. I do not know whether she laid in this exceptionally low nest, as I left for fieldwork elsewhere. On the same farm in the following year, a pair of tityras raised a brood in a hole carved by Red-crowned Woodpeckers only 11 feet up in a slender stub, decayed, riddled by insects, and partly consumed by fire, that stood in an area where second-growth woods had been recently felled and burned for planting maize.
When the tityras took possession of this low nest site it was quite exposed, but by the time the eggs hatched it was barely above the tassels of the tall maize plants that surrounded it on all sides for 100 feet or more. Either cavity resulting from decay or those made by woodpeckers are acceptable to the tityras. The latter seems to be preferred, especially the chambers carved by species of Centurus, Tripsurus, and another medium-size woodpeckers, the doorways of which are barely wide enough to admit the tityra.
Tityras not infrequently capture holes still used by the woodpeckers for sleeping, or even those newly completed for the accommodation of the woodpeckers’ eggs and nestlings, evicting the hole-carvers by persistence rather than by violence, in a manner which we shall consider later. I have not known them to oust the woodpeckers from holes that held eggs or young. Long before the approach of the breeding season, the tityras, roaming in pairs through the forest and adjacent clearings, begin to examine woodpeckers’ holes and other cavities in trees which might later serve as nest sites.
I have watched them pursue these investigations as early as November; indeed, at all times of the year, they display curiosity about the holes in trees that they encounter on their wanderings. The female goes to the doorway of the cavity and looks in, while her mate, who follows her like a shadow, clings to a neighboring part of the trunk, his black-and-white wings half-spread. The male often goes to the doorway, too, after his partner has completed her inspection.
It is usually not until a later date that the birds enter the holes. At times it appears that the examination of potential nest sites may be made before the pair has been formed, or at least before the rivals of the successful male have become discouraged and abandoned their suit. On February 20, 1938, I saw tityras at Vara Blanca for the first time in half a year. On the following morning, I found several of these birds in a narrow clearing in the forest 5300 feet above sea level, where a pair had nested in the preceding July. While a female flew from one to another of the dead trunks standing in the pasture, looking into the many old holes that they contained, three males followed her, sometimes peering into the cavities, too. They voiced low notes, flitted their banded tails fanwise, and sometimes one flew toward another.
But the the individual so approached always retreated promptly, and there was no fighting, nor any suggestion thereof. After the female had made the rounds of the decaying trunks, she flew down the mountain, followed by her three suitors. This observation suggests that the tityra’s method of mating and establishing a the breeding territory is very different from that of finches and many other songbirds, in which the male settles in an area, advertises his presence by singing, and awaits the arrival of a mate.
The female tityra appeared to select the territory while the males followed her about, awaiting her decision. As late as March 6, there were three tityras in this clearing, but by the following day, another of the males had been eliminated. The female’s choice of a partner seemed to have been definitely made, but she has not seen building until April 3. At lower altitudes of 2000 to 3000 feet in Costa Rica, I have known the tityra
o begin building as early as the end of February, at the height of the dry season. March and April are the months of greatest activity in nest building. Pairs saw nest building as late as May are probably preparing for second broods or replacing nests that have been destroyed. Like many other birds, the tityras, especially the female, may gather material some time before they actually begin to build, carry it in their bills awhile and then drop it to the ground. In 1937, a pair of tityras was much interested in the still-occupied dormitory of a pair of Golden-naped Woodpeckers.
I first saw the female tityra with the material in her bill on February 20, but it was March 2 before I witnessed her taking anything into the hole that she had chosen for her nest. Yet two days later she perched motionless near this cavity with a billful of leaves, which she dropped after 12 minutes. While the female tityra was gradually working herself up to the point of beginning to build, her mate seemed impatient to have her proceed with the under- taking. Often, while she paused irresolutely in a neighboring tree, holding a twig let or dead leaf in her bill, he went to cling at the doorway of the woodpeckers’ hole, at times flying off a little way and then returning, as though to encourage her to take the stuff inside. Even when she was beyond sight, he might go to look into the prospective nest cavity, at times in the warmest hours of the afternoon.
For the tityra, nest building is a simple undertaking that requires no art. It consists merely of filling the bottom of the chosen cavity with a loose litter of small dead leaves, or pieces an inch or two long torn from larger ones, fine dry inflorescences of trees, thin twiglets, and rarely a small green leaf. This is done chiefly or wholly by the female, who gathers her material in the treetops, often at a distance from the hole, rather than from the ground, to which adult tityras never seem to descend unless drawn by a fledgling which rests there.
As a rule, she works in a desultory fashion, taking a few billfuls into the hole, then flying off and remaining away until one grows tired of waiting for her return. The male faithfully follows his building partner back and forth, often holding a leaf or twig, which after being carried on a number of trips is finally dropped some- where usually not into the nest. He sometimes takes material to the doorway, both while his mate is building and in her absence. He may do this repeatedly, seeming thereby to express his eagerness to have the female resume her task. The leaf or twig taken to the orifice by the male is often carried away again, and I have seen this happen four times in succession. Often the male drops his material while he clings in front of the doorway.
Nearly always it flutters to the ground, but some- times, that might say by accident, he pushes the leaf or twig far enough inside for it to remain when he releases it. His ineffectual efforts to help his mate in the building are amusing to watch and remind one of the equally unproductive preoccupations with the nest material of the male Black-crowned Tityra.
THE EGGS
The tityras’ nests which are placed high in dead trees of uncertain stability cannot be reached without great difficulty and danger. For many years, the only one that I could examine was about 3.5 feet up in a massive trunk standing in Gatun Lake, about 100 yards from the shore. This tree had been killed about 20 years earlier, when in the construction of the Panama Canal the lake was formed by impounding the waters of the Rio Chagres, and the wood was far advanced in decay. Great chunks of the tree fell off as we threw a cord across the truncate top in order to draw up a rope attached to a rope ladder.
I should never have climbed such a trunk if it stood on solid ground, but a fall into the water seemed less dangerous. In the upper side of a short stub of an ascending thick branch, at the very top of the trunk, I found an irregular hollow, doubtless made by decay, a foot deep and wide enough to admit my hand. Although the cavity opened upward, it slanted down into the wood, so that it gave the tityra protection from both the sun and the direct impact of rain.
When I peered in, I saw no eggs on the loose litter of leaves that filled the bottom of the cavity, but I could feel two eggs under the leaves. These eggs were dark buff or cafe’ au hit in color, heavily marbled, especially on the larger end, with brown. A few small, black spots were scattered over the surface. They measured 30.2 by 20.6 and 29.8 by 21.4 mm. At the low nest to which I gave much attention in 196.5, I could not see the eggs. This nest had an entrance too small to admit my hand, and to have made a larger opening would have endangered the contents. On 15 inspections with a mirror during incubation, I never glimpsed even part of an egg, as all were always completely covered by the leaf litter that filled the bottom of the cavity.
It was the same whether the female had left the nest spontaneously or flew out when she heard me approaching. Apparently, however, this nest also contained only two eggs, for this was the number of nestlings present, and no unhatched egg remained in the litter after the young fledged. Incubation began in this nest in El General at the end of May 1965. At the nest in the Canal Zone, incubation had already started by May 28, 1935. Both were probably second brood or replacement nests. I have no evidence of more than two broods per season in this species
Incubations
Only the female incubates. Often a number of days elapse between the end of the sustained building and the beginning of steady incubation, and in this interval, the female brings occasional billfuls of dry leaves to the nest. Her vacillating behavior in this period is most confusing to the watcher who cannot learn by direct inspection what the hole contains. Sometimes the female is seen looking out of her high doorway, from which at times she darts forth as though to fly away, only to turn after she has gone a few inches and re-enter it. Her mate may remain perched in a neighboring tree, from time to time going to the doorway to look in at her.
As the day ends, the female, often in company with her partner, lingers near the nest cavity, guarding it, but in the waning light both fly off together to sleep in the neighboring forest. After a few more days, the male departs first in the evening, leaving the female perching alone near the nest. As the twilight deepens, she may fly toward the doorway, only to turn back when in front of it, often repeating this move a number of times, but in the end, losing courage or changing her mind, and winging away through the dusk in search of her mate.
Such vacillation is especially likely to be noticed if, as often happens, a family of great-billed aracari toucans sleeps in a neighboring hole. At daybreak, before woodpeckers have emerged from their dormitories, the male and female tityras often fly together from the adjoining forest to perch for a while near their nest. From a cayuco moored to a neighboring stub, I watched the nest in Gattin Lake from 6:00 to 11:23 a.m. on May 29 and from 2:00 to 6:45 p.m. on the following day. In these ten hours, the female tityra took eight sessions on her eggs, ranging from 24 to 49 minutes and averaging 37.1 minutes. Her nine recessed varied in length from 13 to 29 minutes and averaged 19.6 minutes. She was in her nest only 65.4 percent of the observation periods, which is a poor record for so large a bird but is matched by that of the Black-crowned Tityra.
When she left her eggs, the tityra would emerge from the cavity and hop along the broad top of the stump to its highest point, where she usually stood for several minutes, preening her feathers, stretching her wings, or idly looking around, before she flew toward the land. It was remarkable how often her mate, watching from the neighboring forest, saw her before she reached the shore. Sometimes he advanced a short distance over the water to meet her, then together they vanished over the treetops. On five of her ten returns to the nest, the male escorted his partner to the stub standing in the water.
After resting for a minute or more atop the trunk near the doorway, he would fly back to the land, while his mate hopped down into the cavity. Once, as she was returning alone to the nest, the female tityra was attacked above the water by one of the Streaked Flycatchers which was feeding nestlings in a hole lower in the same trunk. The flycatcher plucked at the tityra’s feathers, causing her to cry out in alarm or pain. But as soon as she alighted on the stub, the flycatcher desisted from its attack.
The tityra promptly returned to the shore, as though for consolation from her mate, who a minute later saw her safely back to her nest. On another occasion, one of the flycatchers darted at the male tityra while he rested on top of the stub near his mate’s nest, causing him to retreat to the shore. But aside from these two incidents, the tityras, the Streaked Flycatchers, and the Palm Tanagers nesting in this stub dwelt in peace. The Blue-headed Parrots, whose two large but still naked nestlings rested in a large cavity below the tityras’ nest, remained out of sight the whole time that I watched.
From time to time, the female tityra toot a billful of leaves into the hole when she returned to resume incubation. I have seen other female tityras do the same. I climbed the rope ladder twice more, and each time I found the eggs completely buried in the litter. It was impossible to learn whether the tityra deliberately covered them as she departed or whether the leaves simply flowed over the eggs when she rose from the depression which she doubtless made in the loose mass while she sat. It is probable that the protectively colored eggs often escape predators by being covered with leaves in the bottom of a dark cavity.
In the middle of the afternoon, while the female tityra stood on the top of the trunk beside her nest, preening her feathers, her mate came bearing a big, green caterpillar and alighted close beside her. Without offering the food to her, he hopped to the rim of the nest cavity and looked down into it. Evidently, he had brought the caterpillar in expectation of finding nestlings to receive it, and when he learned that the eggs were still unhatched, he swallowed it himself. The male tityra not infrequently brings food to the nest in this anticipatory fashion, finds that there are still no young mouths to take it, then eats it himself or carries it away.
At another nest, I saw the male do this twice. Since, even while the two are attending nestlings, the male tityra does not pass food to his mate, these morsels are obviously not for her. Similar anticipatory food bringing has been witnessed at nests of a number of other passerine birds, especially those of wood-warblers and tanagers. It serves to form in the male parent, when he does not incubate, the habit of bringing food to the nest in advance of the hatching of the nestlings, with the result that after the young are hatched he will promptly find and attend them.
Seated on a log amid the maize plants which partly screened me, I watched the low nest in the milpa from 5:20 to 11:36 a.m. on June 5, and from noon to 5:40 p.m. on June 7. In nearly 12 hours, this tityra took 14 sessions on her eggs, ranging from 4 to 81 minutes in length and averaging 2 1.6 minutes. An equal number of recesses varied from 10 to 26 minutes and averaged 17.1 minutes. She spent only 55.7 percent of her active day on the nest, but this day was short. It began at 5:23 am on June 5, when the tityra left her nest in the cloudy dawn. Until 2:23 p.m. on June 7, she had come and gone very frequently, taking no session longer than 26 minutes. After her return to the nest at 2:23, the sky became darkly over-cast and intermittent sprinkles fell, hardly enough to wet the foliage.
The tityra now stayed in her nest continuously for 81 minutes. When finally she emerged at 3:44 p.m., it was only to rest in a neighboring dead tree, preening, scratching, and stretching her wings, until her return to her eggs at 4:02. Then she remained within continuously, never even showing herself in the doorway until I left when daylight was waning at 5:40 p.m. From 2:23 p.m. until nightfall, this tityra took no food.
In comparing the incubation records of the two tityras, it should be noticed that the Canal Zone, where the first nested, is only about four degrees east of El General, where the second nested, yet the first locality uses standard time for the seventy-fifth meridian and the second that for the ninetieth meridian, and their clocks are accordingly an hour apart. Hence the sun rises and sets, by the clock, much earlier in Costa Rica than in Panama. The tityra in the cornfield could barely squeeze through the round doorway of her nest hole that the woodpeckers had made.
She seemed to have little difficulty finding enough food in the neighboring forest where she foraged, for some times, even early in the morning, she would spend part or even the whole of her recess preening in a neighboring dead tree, often in company with her mate. He was attentive to her, and as she returned to her eggs he would often fly down with her, to rest atop the low stub while she entered the opening in its side. Once he clung before the doorway and pushed a piece of the dead leaf through it. Sometimes the female carried pieces of dead leaf in her bill when she went to resume incubation. This female was found in her nest late in the afternoon of May 29, and again on the following afternoon. Incubation had apparently begun by the former date.
One of the unseen eggs had hatched by 7:20 am on June 19, and the second egg no later than the next morning, after an incubation period of about 21 days. THE NESTLINGS Hatching and the beginning of feeding.-Bracing the back of the rotten stub in the cornfield and setting my ladder almost upright against the front, I climbed up and looked into the nest hole with electric light and mirror, at 7:20 a.m. on June 19.
Now for the first time, I saw part of an egg-half of an empty shell. Its dark color made it difficult to distinguish from the leaves among which it rested. I heard peeps and from time to time saw the leaves move, but I could catch no glimpse of the newly hatched nestling(s) hidden beneath them. Both parents were resting in a dead tree at the edge of the field. Presently the male flew away and his mate fo8110wed. At 8:Ol she returned and entered the nest with a dead leaf in her bill, while the male rested on top of the stub. She brooded for 40 minutes, then left carrying a piece of eggshell.
When she returned 11 minutes later, she again held fragments of leaf, which she dropped while standing on the end of the stub before she entered. Now she brooded for 18 minutes, was absent for 19 minutes, and on returning at 9:29 she held a small green object that was evidently an insect, the nestling’s first meal. After another spell of brooding and another excursion, she again returned with a billful of leaf fragments which, before approaching the nest, she dropped while perching in a dead tree at the side of the field. Then she flew back to the forest, evidently for more food. Returning, she entered the hole so swiftly that I could not see whether she had brought anything.
But apparently, she fed the nestling, for she remained with her head down and her tail sticking up in the top of the hole for about a minute. At 1054 the male and female returned together and clung side by side to the top of the nest stub. The female had food in her bill. While she delivered it with her tail pointing upward at the top of the nest cavity, her mate looked in through the doorway. He returned to the top of the stub, but a few minutes later he again went to peer inside while clinging in front. Thereupon the female left, but he remained clinging to the stub for about a minute more before he followed her.
He evidently had intimations that some important change had occurred in the nest, for now, he spent more time on the stub than he had formerly done. Once more he looked in while his mate fed the nestling. Finally, at 11:42, he flew from the dead tree directly to the doorway with a small piece of food in his bill, entered, stayed in for about a minute, and emerged with empty bill. He first fed the nestling two hours and 13 minutes after the female did, and four hours and 22 minutes after I found the empty eggshell and heard the nestling peep. By noon, he had fed the newly hatched young twice; the female had brought food five or six times. When I looked into the nest at 8:00 the next morning, I could see parts of two nestlings. One promptly disappeared beneath the leaves, but most of the other, except its head, became visible when it shifted its position.
The few tufts of fairly long, light gray down that it bore on its head, wings, and back were far too sparse to cover its pink skin. I could not induce it to gape. This was the most adequate view that I was to have of a nestling for many days. For the next two weeks, they were always beneath the leaves, with rarely ahead exposed, whenever I looked into the nest. Brooding.-Perhaps because they were embedded in dry leaves in a snug nursery, these nestlings were brooded little.
During five hours of the morning of June 25, when they were about six days old, their mother brooded them only three times, for 28, 12, then 14 minutes. When 12 days old and still practically naked, the nestlings were not brooded at all during the first five hours of the morning.
Feeding.-The number of meals delivered by both parents on six mornings is recorded in table 1. As far as seen, each meal consisted of a single item. Until the nestlings were over 24 days old, there was no significant increase in the rate of feeding, but after the first week, the parents rather consistently brought articles that were noticeably larger than those which newly hatched nestlings had received. Rarely they offered the nestlings an insect so big that it was swallowed with difficulty, or not at all.
This regimen of few but substantial meals was followed until a few days before the young left the nest when feedings became twice as numerous as they had been through most of the nestling period but the articles of food were often small. In 30 hours of watching, the number of meals received by the two nestlings in a single hour varied from 0 to 11; they were fed a total of 93 times, or at the rate of about 1.5 meals per hour for each of them. The nestlings’ diet consisted chiefly of insects, especially orthopterans.
The green color and massive bodies of many of these insects suggested that they had not been caught in the air but had been snatched from foliage, where their protective coloration had failed to conceal them from the tityras’ sharp eyes. Sometimes a brown or dark-colored insect was brought, once a large orange-tawny butterfly, and twice I detected a large spider in the male’s bill. Occasionally a small land snail was taken to the nestlings, as I learned when I found three small shells in the litter in the bottom of the nest after the young had flown. At other nests, I saw the parents bring caterpillars, and rarely a small lizard.
No fruits were detected in the parents’ bills when the nestlings in the cornfield were six days old, but when they were 12 days old they received a few. The rather large, green, olive-shaped fruit of a lauraceous tree was the kind most often brought. Each contained a single big seed surrounded by hard, thin flesh. After this had been digested away, the young birds regurgitated the seeds, of which I later found many among the leaves in the bottom of the nest. Each seed was from 3/a to 7/s inch long and about % inch thick. During the nestlings’ last days in the hole, they received an increasing number of bright red arils from the seeds of the “candela” a large tree of the nutmeg family that was then beginning to ripen its fruits.
Usually the big seed had been removed from the enclosing aril before the parents brought the latter to the nest. These brilliant arils could have come only from the forest 200 yards away, where the tityras seemed to find most of their food. They were never seen to forage in the cornfield in the midst of which their nest was situated. At first, the parent entered the hole and was completely hidden from me while it fed the nestlings, although sometimes I could detect its tail sticking up in the top of the cavity.
When the young were 12 days old, the parent fed them while clinging upside-down in the doorway, its foreparts down in the hole and the tip of its tail projecting from the top of the aperture. Sometimes after delivering the meal it entered to turn around and perhaps collect a dropping, and sometimes it backed out. After the nestlings were 18 days old, the parent nearly always clung to the trunk and passed the food through the doorway; very exceptionally, if the young were sluggish in taking the meal, the adult would enter to deliver it.
At first, the parent clung in front of the doorway, but later, when the nestlings stuck their heads out to receive their meals, it might cling around the side of the slender stub, somewhat above the level of the doorway, and reach down to place the food in the recipient’s open mouth. The parents took fairly equal shares in feeding the nestlings, but on most mornings the female fed them more often than did the male. In 30 hours of watching, she brought food 53 times, he 40 times.
At an inaccessible nest with at least two young that were no longer brooded by day, the male brought food nine times and the female ten times in three hours. If the male arrives with food while his partner is in the nest brooding recently hatched nestlings, he does not, like many male birds, give it to her to be passed to the little ones she covers, but he alights nearby and continues patiently to hold the morsel until, at her own good time, she departs, leaving the nestlings free to receive what he has brought for them.
I have seen this inefficient behavior at several nests. Once I watched a male wait for a quarter of an hour, from time to time going to look into the hole, or voicing a slight grunt to proclaim his presence, until at last his brooding partner flew away and he could feed his offspring. At times, however, the male tityra grows tired of waiting for his mate to leave and carries away what he has brought. At one nest, the male somehow lost his tail, but despite this handicap, he continued faithfully to feed the nestlings.
Sanitation - During five hours of the sixth morning after the nestlings hatched, I saw only one dropping carried from the nest, by the male. Additional droppings had evidently been swallowed by the parents inside the hole. On the twelfth morning, the white fecal sacs were carried away although sometimes they were swallowed. By the eighteenth morning, the parents could reach inside to take the droppings while they clung before the doorway; less often, they entered to remove a dropping.
On the the twenty-seventh morning, the male entered the nest after delivering a lauraceous fruit, evidently to clean the interior. When he tried to come out, he was stuck in the doorway. After a great struggle to squeeze through, he finally emerged upside down! Later the female also had a hard time getting out, yet both had entered without difficulty. Possibly while cleaning the nest they had swallowed enough of the large seeds regurgitated by the nestlings to increase their girth to an unusual degree.
This explanation was suggested by the recollectioln of a Blue-throated Toucanet which had entered a nest hole with a lauraceous fruit that seemed too large for his nestlings to swallow. When he tried to pass outward through the doorway by which he had entered, he stuck so firmly that he could not move until he reduced his girth by regurgitating the fruit, which he held in his bill until he regained his freedom, then swallowed once more. During the young tityras’ last few days in the nest, the parents often swallowed the droppings instead of carrying them away in their bills.
The young birds had remained beyond the time when their feces were enclosed in the gelatinous sacs that facilitate their disposal. He leaves to the in earlier years, I had often seen tityras carry pieces of leaf to nests that held young. Sometimes the parents dropped these bits of the leaf while they rested near the hole, and sometimes they did so while clinging in front of the doorway. At times the parents at this latest nest brought an odd billful of leaves, which they might drop or take into the hole, and at intervals, they brought this material in a concentrated, purposeful manner. Thus, between 10:00 and lo:19 on the sixth morning after the nestlings hatched, the male entered the nest five times and the female four times.
Sometimes they went in so swiftly that I could not see what they carried, but on four occasions I clearly saw that they held leaves, and I believe that on all of the nine visits they brought this material rather than food. In all the rest of the morning, up to 10:30, they fed the nestlings only ten times. The parents are especially likely to bring leaves and drop them outside the nest in moments of excitement, as when some critical event in the nesting cycle has just is about to occur, or when their nest has just been visited by a man. It will be recalled that the first two billfuls that the female brought to the nest after an egg hatched were leaves, not food.
And two minutes before the first nestling flew from the nest, the female came with leaf fragments, which she dropped in front of the young bird’s open mouth in the doorway. Another female tityra, whose three-week-old nestlings had apparently just been lost, gathered a billful of dead leaves in the top of a neighboring tree, then let them fall to earth. The drive to gather leaves is strong in tityras apparently because leaves play an exceptionally large part in the birds’ domestic economy.
Not only are they the principal-sometimes the only-ingredient of the nest, but for some five weeks they serve to conceal the eggs and young from predators that might look into the hole. And at an earlier stage, tityras often gain possession of the holes in which wood- peckers or araqari toucans sleep or are preparing to nest by filling them with leaves and other materials with such persistence that the occupants finally abandon them, as told in more detail beyond.
Development and behavior of the nestlings.-My single reasonably adequate view of a newly hatched tityra revealed that it was blind, with pink skin that bore a few tufts of light-colored down. In the next few days, the glimpses I had of small portions of the nestlings that showed through the leaves revealed that their skin had become much darker, but it never became quite black.
Once I heard a weak peep peep peep while I looked into the nest, and occasionally the leaves would move, but usually the nestlings lay in silent immobility. After a few days, I was more likely to see portions of their heads than of their bodies, and when they were ten days old, I found both nestlings lying with their heads completely free of the leaves which covered the rest of them. Three days later, they were also lying with exposed heads and concealed bodies. Then, when the elder was 15 days old, I discovered one of them resting wholly exposed, although only the head of the other nestling was visible. Thereafter, throughout their final two weeks in the nest, they were never again found beneath the leaves. They were always silent and immobile while I peered in at them.
When, after an the interval of two weeks, I, at last, saw the nestlings entire, their dark skin was still nearly naked. The pins of the remiges were prominent, but those of the rectrices were much shorter. I could no longer detect any natal down them; possibly much of it had been rubbed off by the leaves that covered them, but an odd tuft was still present when they left the nest. While I looked in, they kept their eyes tightly closed. They were silent; nothing that I could do, from the time they hatched until they left, would stimulate them to open their mouths. Two days later, when the nestlings were 17 days old, their eyes were open, and both the contour and the flight feathers were expanding at the tips of their sheaths.
At this age, the young could reach up so far that the parents fed them without entering the nest. Once, indeed, I glimpsed an open mouth in the doorway, and at last, learned that the interior was orange-yellow. The flanges at the corners were whitish. When the nestlings were three weeks old, they were at last fairly well covered with plumage, but their flight feathers were still largely unsheathed. Now, if they were very hungry, their heads would often appear in the doorway when a parent arrived with food. Aside from the weak peep’s that I heard from the nestlings when newly hatched and again a few days later, I heard no note from them until the fifteenth day after they hatched-the day on which I first saw one of them completely exposed.
While I stood only about 25 feet from the nest, hardly concealed by the maize plants, the male flew to the top of the stub with food in his bill. Recognizing the arrival of the parent by the sound or vibration he made when he alighted, the nestlings repeated little sharp notes while he stood hesitating. They continued this chorus while, standing in the doorway, he fed them. Two days later I approached carefully, tapped the trunk and shook it slightly, trying to reproduce the sound and vibration made by a parent alighting there.
The nestlings set up a chorus of the sharp notes that I had previously heard, but they fell silent as soon as I set the ladder against the stub. Soon they learned to distinguish my simulation of a parent’s arrival from the real thing, and would no longer respond to it. Until they left the nest, I heard their peculiar, sharp notes with increasing frequency, especially when they were hungry. I can best describe them as “sucking” notes, such as one can make by suddenly opening his lips as he draws in his breath.
Departure.-On July 13, when the nestlings were 24 days old, the female from time to time alighted on the top of the nest stub and called. On the next day, this behavior was more frequent and pronounced. Without food, she would come to stand on the end of the stub, a few feet above the nestlings, repeating her sharp, dry notes and twitching her tail with a rapid movement that combined a slight fanwise opening and closing with a little vertical flick. Her calls consisted of one, two, three or, rarely, four notes.
The monosyllable, a frequent call at all seasons, was the strongest. The more syllables that the phrase contained, the shorter and weaker each became; the insect-like notes of the tetrasyllable were so weak and rapidly delivered that it was difficult to distinguish all of them. These short, dry notes, uttered with twitching tail, suggested urgency and impatience. After standing atop the stub and behaving so for a few minutes, the female might fly off, only to return promptly and repeat the performance.
She was obviously trying to call out her nestlings, now well feathered. The male never behaved in this fashion. From first to last, he seemed not to care whether they stayed in the nest or left, but continued faithfully to attend them wherever they were. The female’s excited notes were not without effect on the nestlings. At eight o’clock, while she stood calling on top of the stub, a young tityra pushed its foreparts through the doorway, farther than I had seen it emerge before. Then the male gave it a large green insect, and it went down inside.
When the female repeated her performance half an hour later, a nestling stood on the door-sill, looking around and giving “sucking” notes that were audible to me 60 feet away. But soon it returned into the nest. Later in the morning, it again leaned so far out that I expected it to leave, but it did not. On the following day, July 1.5, the female seemed less eager to bring her family into the open. Although she rested a good deal atop the stub, she did not, as on the preceding day, arrive there without food. While standing there, she called much less, and her voice sounded less urgent. Likewise, she twitched her tail much less.
Apparently, the excitement caused by the nestlings’ greater activity and the imminence of their departure was on July 14 expressed by impatience, at least on the part of the female, to have them make their exit, whereas on July 15 it was expressed by a greatly accelerated rate of feeding by both sexes. On this morning the parents fed the nestlings twice as often as on any previous morning that I watched them.
On July 16, when the elder nestling was 27 days old, activities at the nest followed much the same pattern as on the preceding day, with occasional calling by the female from the top of the stub, responses by a nestling that brought it into the doorway but no farther, and an even higher rate of feeding. Tityras of two species (see the preceding life history) have been more obviously eager to have their young leave the nest than any other birds that I have watched, most of which have seemed indifferent whether their offspring lingered in the nest or came out into the world.
The fact that the tityras’ attempts to induce their young to leave were associated with a greatly accelerated rate of feeding weighs heavily against the persistent belief that parent birds withhold food from their young to force them by hunger to leave the nest. Such behavior might defeat its own purpose, for unless the nestlings promptly gave the desired response, the longer it was continued the more debilitated and the less able to meet the demands of life in the open they would become.
On July 17, when one of the nestlings was just four weeks old, I arrived later, at 6:35 a.m. while the sun was shining brightly. Neither parent appeared until 653, when the female came with a billful of leaf fragments, which fluttered to the ground when she dropped them in front of the open orange-yellow mouth of the nestling in the doorway. Then she rose to the top of the stub and called with single, double, and triple notes.
She flew off, but promptly returned and called as before. The young bird which had been standing in the doorway looking out now launched itself and flew down into the corn, with the female following from the top of the stub, at 6: 5 5 a.m.
As soon as the first fledgling left the doorway free, the other one looked out. The female returned to the top of the stub and called briefly. During the next two hours, she tried hard to induce it to leave, in the manner already described. Often it stood in the doorway as though about to go, but it was not yet ready. In these two hours, it was offered food seven times by both parents, but once it refused because it was satiated. I could not see how many meals the fledgling down among the maize plants was receiving.
At nine o’clock, I went to look for the fledgling, which I promptly found on the ground in front of the nest. It tried to escape me by hopping over the ground and flitting from one charred branch or prostrate log to another, but despite these obstacles to my progress, I soon caught it. When I picked it up, it hardly resisted. The fledgling was well feathered, its plumage resembling that of the adult female. Its dusky remiges were well developed, unsheathed only at the base for a quarter of their length or less. Its blackish tail feathers were rather long but still about one-half unsheathed.
A single tuft of natal down, long, loose, and light gray in color, adhered to the tip of a contour feather on the back but became detached and blew away. The fledgling’s bill was blackish, slightly lighter at the base. The whole interior of its mouth was bright orange-yellow, and there were whitish flanges at the corners. Its eyes were deep brown, and the bare skin surrounding them was grayish, instead of red as in the adults of both sexes. Its legs and toes were plumbeous.
I set the fledgling on a stump near the nest, where it stayed. It seemed rather underdeveloped to have left its sheltering nest. Next morning, I found it 50 yards away, beneath a dead tree standing in the middle of the milpa, from which the parents had been dropping almost straight down with food in their bills. The fledgling was perching as high as my head on a dead branch. Far more alert than the day before, it took wing as I approached and flew off competently to alight on a maize plant.
It now seemed quite able to escape all but winged pursuers. For two days after the departure of the first fledgling, the parents continued to feed the other young tityra in the nest. In this interval, the female tried again and again to persuade it to leave. Although her excited urging obviously stimulated it, it would look from the doorway, rapidly repeating cucking” notes, only to lose courage and back down into the safety of the hole. It did this again and again.
Once, indeed, while taking its meal, the nestling stretched out so far that one leg slipped outside. After a struggle, it pulled itself back into the cavity. Finally, at 8:OS a.m. on July 19, the adult female alighted atop the stub and called, as she had done so many times before. The nestling alternately looked out and withdrew. But when, a minute later, its parent flew off, calling, it flew from the doorway in the same direction, to come down among the corn. Three minutes after this, the female returned with a large insect, which she took to the doorway of the empty nest.
After looking in several times, she carried it down to the newly emerged fledgling. Both of the young tityras left the nest while their parent was calling for them to go, but apparently her urging was effective only after their own internal development had prepared them to respond to it. For tityras, it may be more important to leave the nest only in the presence of a parent than it is for most other land birds. Many of their nests are so situated that they must fly hundreds of feet before coming to rest, and they might be lost if no parent watched or accompanied them.
Moreover, on this long flight the fledgling would be particularly vulnerable to a bird of prey, and their parents doubtless would not call them out if such an enemy were in sight. Leaving my observation post, I found the second fledgling in a patch of bracken fern only three yards from the nest stub. When picked up, it bit my finger gently and struggled a little, but soon rested quietly in my hand. Its plumage was slightly less developed than that of its nestmate had been two days earlier.
When I set it on a fallen branch amid the maize, the female alighted four yards from me and only about a foot above the ground-closer to me and to the earth than I had ever seen an adult tityra before. She called the fledgling with phrases of two and three syllables, as she had done while coaxing it to leave the nest. It hopped over the ground and fluttered toward her; it could fly only a few feet. Calling as before, she flew toward the dead tree in the center of the milpa and the fledgling fluttered after her. This was the last time that I saw either fledgling. Next day I could find neither them nor their parents in the cornfield.
Doubtless, as is usually the way when a brood is raised in a clearing, as soon as the young birds could make the journey they were led to the neighboring high forest, whence I heard a tityra’s call. The first nestling had remained in the nest a full 28 days, the second, 29 or possibly 30 days. Probably they survived this long period in their low nest because I had wrapped an opened five-gallon tin around the stub to keep down climbing animals. A slight push sufficed to overturn the rotten stub so that I could examine the contents of the nest. The doorway was 2 inches in diameter. The soft wood at the lower edge of the orifice had been worn down by the tityras’ feet during the two months that they had been passing through and clinging to it. The cavity, which ex- tended 9 inches below this edge, was 3 to 3% inches in diameter.
On the bottom was a little dry moss. I do not know whether the tityras had carried this in; I have never seen them with such material. Above the moss was an accumulation, 2 or 3 inches thick, of pieces of brown dead leaves. The lower part of this litter was compacted into a coherent mass, but the upper part was loose. The largest piece was a nearly whole leaf 2% inches long by half as broad, but most of the leaf fragments were much smaller, ranging down to tiny bits. Mixed with the loose leaves were many regurgitated seeds, chiefly of the lauraceous fruit that I had so often seen the parents carry in, detached fragments of the legs and wings and other parts of large insects, and three small snail shells.
There were also a few whole shriveled fruits of the same lauraceous tree. The nest had been kept as clean as could be expected, given the tendency of waste to slip down among the loose leaves where it was difficult for the parents to find. Although the hole had a peculiar odor, I detected no vermin of any kind. For 18 days after two young tityras left a high nest in a clearing, I could not find them. Doubtless they were being attended by their parents in the neighboring forest.
At the end of this interval, they sometimes followed the adults into the clearing, where the female was incubating a second brood. After a few more days, they were no longer seen in the vicinity, having apparently become self-supporting about three weeks after quitting the nest, at the age of about seven weeks. THE SECOND BROOD In Costa Rica, the tityras frequently, if not regularly, attempt to rear a second brood when they have successfully brought forth their first brood at an early date.
A female whose nestlings had departed on or shortly before April 29, 1936, was seen to enter and rest in the doorway of the nest hole on May 9 while she and her mate were still feeding two full-grown young birds. On May 11, she went into the cavity in the evening to pass the night. By May 17, she was certainly incubating again in the nest where her first brood had been reared, leaving her mate to attend the young birds, which seemed rapidly to be becoming self-supporting. By June 5, both parents were feeding the nestlings of the second brood, their older offspring having meanwhile gone their own way.
By June 25 the nest was empty; and although the fledglings could not be found, the aggressive behavior of the usually mild parents suggested that their young were hiding nearby. In later years, additional evidence for second broods was gathered. Nestlings have been found as late as mid-July. TERRITORIAL RELATIONS The Masked Tityra is decidedly a ‘Yerritorial” bird.
Indeed, it is one of the relatively few tropical birds, especially among those of the treetops, which I have seen engage in disputes over territory, although these have been carried on with less violence than is often witnessed in similar contests by northern birds. A clearing by the forest, several acres in area, may contain a number of fire-killed trees, each of which has one or more holes that would be suitable nest sites for tityras; yet I have never known more than one pair to breed in such a clearing.
The only tityras’ nests that I have seen at all close together were those in the three palm trees already mentioned. Possibly the circumstance that the wide-spreading fronds of the palms screened the tityras from each other, enabled these three pairs to nest closer together than one would find them in the usual dead and naked trunks, where they are visible from afar. While one pair of tityras nested in a tall dead trunk in a clearing beside the forest, a second pair came to investigate the woodpeckers’ holes in another dead tree about a hundred yards distant. Presently the visiting female brought a piece of dead leaf, but as she carried it toward the hole that she had chosen, the resident pair discovered the intruders and, flying at them, drove them unresistingly away.
Two days later, in a neighboring clearing, I watched a female, evidently the one which had been denied the use of a cavity, try again and again to force herself into woodpeckers’ holes too small for her, while her mate looked on. This behavior suggested that there was a shortage of suitably isolated holes for the tityras. At the end of February, when a pair of tityras established in a large clearing were preparing to nest, their territory was invaded by a small flock of their kind, consisting of four males and a female. The invaders and the resident pair rested not far apart, called in their thick, grunty voices, and twitched fanwise their short, black-and-white tails.
Presently one would dart at another, who would quickly change his position to avoid a collision; and this might cause a general shifting around of the whole group. After a while, one would start to fly across the clearing, and some or all of the others would follow closely. They might all settle together in another tree in the clearing or at its edge, or else they would fly beyond sight over the neighboring forest. But soon they returned to grunt, dart at each other, and fly about in a loose flock as before.
In the ensuing days, the number of invaders dwindled, until the resident female was followed by only two males. When finally the number of males had been reduced to one, her mate, the female gathered a billful of leaves and took them into the hole-the first material that she carried inside in my presence. Weeks later, when the resident pair was feeding nestlings in this hole, two trespassing males followed the female as she took food to the nest. They perched nearby until the male parent of the nestlings arrived with food and, without even clearing his bill, drove them away simply by darting toward them.
Unattached male tityras seem often to travel two or three together in search of a mate, and their presence at the height of the breeding season indicates that there are more males than females. From May 24 to June 17 of 1939, two pairs of tityras contended for the possession of a tall, many-branched, dead tree that rose above a low second-growth thicket 200 yards from the forest, and which apparently they desired for rearing a second brood. This arboreal skeleton contained enough unoccupied holes to provide nest sites for several pairs of tityras, but each pair insisted on having exclusive possession of the tree and the surrounding area. The protracted dispute was carried on with characteristic mildness of temper, patience, and persistence. All four of the tityras would rest among the dead branches, often close together, apparently in perfect amity.
Of a sudden, one would dart at a member of the other pair, causing it hastily to shift to a different perch. Then all would flit about confusedly for a few moments, apparently greatly excited, voicing their grunty notes and twitching their tails as they rested between movements. They rarely, if ever, struck each other, for the individual which saw itself the object of another’s attack invariably retreated. When the flare-up ended without any participant having suffered the slightest injury, all rested from their nervous exertions quietly side by side as before.
Soon becoming hungry, all four flew off to the forest, where doubtless they foraged in unruffled fellowship. After a brief absence, all four returned together to the dead tree, to resume the interrupted argument in the same intermittent fashion. Some times the dispute continued until evening, when the two pairs flew toward the woodland as though to roost together. By June 25, a month after I found these two pairs quarreling oven the tall dead tree, neither pair had begun to nest in it.
The season was now so far advanced that further breeding was improbable. Were tityras fiercer and more decisive birds, doubtless the dispute would have been settled promptly, possibly by the maiming or death of one or more of the contestants, and the victorious pair would have proceeded to nest. But the two offspring which they might then have reared, if enemies of many kinds had not destroyed the eggs or young, would merely have sufficed to replace the casualties of their battle; the net increase of the local population would have been small or null.
Since in this locality tityras were already so numerous that every clearing which provided a nest site had a breeding pair and there was a shortage of suitably isolated old woodpeckers’ holes and other cavities, the failure of these two pairs to rear broods (probably second broods) was far from deplorable; for any increase in the population would have created more serious difficulties in the following years. We often wonder how tropical birds preserve their numbers at a fairly constant level from year to year, avoiding the great fluctuations in population which many birds and mammals of high latitudes exhibit.
This episode of the tityras shows us one of the ways in which the regulation of numbers is accomplished. While the Masked Tityras argued over the dead tree, a pair of Black-crowned Tityras built their nest in one of its cavities, undisturbed by them. Although rather similar in coloration, Black-crowned Tityras do not arouse the territorial jealousy of the Masked Tityras, as do others of their own species. The former may rest undisturbed close by a nest of the latter, and both at times breed in the same clearing. Although tityras defend nesting territory, they seem not to defend a feeding territory. Since the clearing where they often nest provides little or no food, it is strange that a breeding pair claims such a large area.
RELATIONS WITH OTHER BIRDS
As in many other birds which nest in holes which they do not make, the tityras’ mode of life brings them into competition not only with wood-carving species but also with other hole-users in the same plight as themselves. In the first category are the woodpeckers whose holes they covet, often before the makers have abandoned them; in the second class are Southern House Wrens, Gray-breasted Martins, Black-crowned Tityras, and, above all, aracari toucans, which nest and sleep in holes carved by the larger woodpeckers. In El General, a favorite nest site of the tityra is a deep, spacious cavity carved high in a fairly sound dead trunk by Golden-naped Woodpeckers. One great advantage of these holes is that the narrowness of the doorway keeps out Fiery- billed Aracaris, which easily enter chambers made by larger woodpeckers such as the Lineated and the Pale-billed.
After a successful nesting, a pair of Golden-naped Woodpeckers sleep with their offspring, often in the hole in which the latter was reared, until the the approach of the following nesting season, when the young disperse and the parents move into a newly carved hole in which the female soon lays. Tityras may carry litter into the woodpeckers’ old dormitory before the new one is large enough for occupancy.
When the woodpeckers arrive in the evening and find the bottom of their usually clean chamber covered with trash, they may throw out many pieces, but at other times they sleep above it. If another old hole is available, the Golden-napes may roost in it rather than in that which the tityra is filling. In these circumstances they are often very unsettled, changing their lodgings a number of times until they are finally installed in the new hole, where they soon incubate. I have seen a pair of tityras dispossess, without any fighting, a pair of Golden- napes of the lodging they had occupied for many months.
If the woodpeckers were carving at their new hole lower in the trunk when the tityras arrived, they appeared uneasy and sometimes flew away. Rarely a tityra darted toward a woodpecker while it was at work and caused its prompt retreat. But the tityras also seemed to be slightly afraid of the woodpeckers, so that encounters were carefully avoided by both parties. Similar relations between Golden-naped Woodpeckers and Black- crowned Tityras are described in the chapter on the latter.
Although tityras are usually mild, peaceable birds, occasionally one finds an individual with a fiery temper. While a pair of tityras and a pair of Golden-naped Woodpeckers reared their early broods in the same dead tree, I noticed no enmity between them. But while the female tityra was preparing to rear a second brood in the same hole as the first, her attitude toward her picarian neighbors changed. One evening she perched at the top of the tall dead tree and darted at the woodpeckers as they approached their hole, which had now become the dormitory of the parents and two male offspring. Swooping down, with an audible snap she came so close that they fled to other trees, and she repeated this threat whenever one of them returned.
She kept the woodpeckers out until long past their usual hour for retiring, but as it was growing dark she stood quietly atop the trunk and watched them cautiously slip into their chamber below her. Next morning, she twice flew menacingly at a Golden-nape which rested inoffensively in a treetop 50 yards from her nest. But after this she calmed down and incubated her eggs without, as far as I saw, again molesting her near neighbors the woodpeckers. On the Caribbean slope of Costa Rica, I watched a pair of tityras gain possession of a freshly carved hole in which Black-cheeked Woodpeckers seemed to be preparing to nest. When the female tityra carried leaves into their hole, the woodpeckers promptly began a new cavity lower in the same trunk, where, as soon as it was large enough, they slept and later nested.
Here, as with the Golden-naped Woodpeckers, the change in possession of the hole was effected, as far as I could tell, without any fighting. I have not known tityras to try to capture a woodpecker’s hole that held eggs or nestlings. High in the mountains, a male Golden-olive Woodpecker proceeded to throw out the material which a tityra had carried into an old cavity, in which he had not recently been sleeping and which, apparently, he did not desire for nesting. Although the woodpecker continued on two days to clean out this chamber, I noticed no fighting between the two kinds of birds.
When the woodpecker looked into the hole and found a tityra within, he promptly flew away as though alarmed. The tityra’s relations with the brilliant Fiery-billed Aragaris are more complex than those with woodpeckers. Not only do the two species compete for the possession of the big holes abandoned by the early-nesting Pale-billed and Lineated woodpeckers, but the tityras fear these great-billed nest-robbers for the injury they may inflict on themselves or their offspring. Sometimes the tityras choose as a nest site a cavity in which several araqaris roost.
At first, perhaps, they are unaware that the hole has prior claimants, for the toucans may be absent in the daytime while the female tityra carries leaves into their dormitory. Soon, however, the tityras discover that they have to contend with these birds to which all the smaller feathered creatures have a great antipathy. Then, as the day ends, the tityras take com- manding positions near the hole, from which they harass the aracaris when they come to enter their dormitory, darting back and forth above their heads while they perch, pursuing them closely in flight, and swooping close by them while they cling before the doorway to inspect the interior of their cavity before they enter.
