Red-crowned ant tanager – The dim underwood of the tropical rain-forest is not an environment that favors the production of intense colors in either the vegetable or animal kingdoms. The bright red flowers of some acanthaceous shrubs, the scarlet of the great vine-leafed passionflower, the intense azure of the morpho’s wings, the flashing green and violet of the wood-nymph hummingbirds, the vivid bill of the Orange-billed Sparrow-these are outstanding exceptions in a habitat where blossoms tend to be small and dull, and birds are clad in shades of brown or olive.
The bright colors of the tropical forest are concentrated in the sunbathed upper levels, where trees and creepers and epiphytes display lavish masses of bright flowers and where the brilliant parrots, toucans, hummingbirds, trogons, cotingas, and honeycreepers occur.
Here in the woodland treetops, or in the clearings that admit the sunlight, dwell a great variety of tanagers, that most colorful avian family of the western hemisphere. Few of these birds are at home in the undergrowth of the heavy forest; and here they tend to lose the brilliant hues of their family, to become more like the dull antbirds, ovenbirds, and flycatchers with which they mingle. One of these exceptional genera of tanagers passes their lives in the underwood of the heavy forest of Habia or Phoenicothraupis, which is widespread throughout tropical America.
The Red-crowned ant tanager (Habia rubica) is one of the larger members of its family, about seven inches in length. The male is deep, dull, subdued red on the upper plumage paler on the more posterior underparts. From time to time one catches a glimpse of vivid scarlet in the middle of the black stripe that runs over the top of his head. This vivid color belongs to an erectile crest of elongated, narrow feathers that is seldom fully displayed, and then but briefly, although it is not infrequently partly revealed.
The female’s plumage is olive, with a greenish tinge in full sunshine. Her throat is more yellowish; and over the top of her head, there is a median dark stripe which at times parts to reveal a hidden patch of dull orange or ochre, corresponding to the scarlet crest of the male. In both sexes the thick bills are dusky and the eyes brown.
It can be distinguished by the dark stripe which forms a border on either side of the expanded bright crest. The Rosy-throated Ant Tanager lacks this contrasting margin. The Red Ant Tanager extends across the tropical American mainland from southern Mexico to northern Argentina, Bolivia, and western Ecuador.
The Panamanian form, H.r. vinacea, chiefly occupy attention, is restricted to Panama and Costa Rica. In the latter country, it ranges upward, at least 4000 feet above sea level; and in the basin of El General, found it fairly abundant up to 3300 feet.
Here it is a bird of the heavy primary forest, beyond whose vine tangled borders it scarcely ever wanders. Although dooryard borders the woodland where it roams, and from which at times its notes are heard, have not once in a dozen years seen it among like shade trees. It has never come to sample bananas on the feeding shelf that attracts so many other kinds of tanagers.
In this it resembles a great many other birds of the understory of the rain-forest; although some, like the Orange-billed Sparrow and the Bicolored Antbird, occasionally wander into the open, and others, like the Blue-black Grosbeak and Salvin Manakin, habitually do so. Although the Red Ant Tanager constantly proclaims its presence in the Underwood of the forest by its incessant chatter. It is not for that reason easy to observe; for it is skillful in keeping itself screened by the dense foliage and exceedingly restless.
It is so constantly shifting its position and flutters from bush to bush that even if one succeeds in seeing it, as a rule, enjoys but a fleeting glimpse. These birds usually remain near the ground, rarely rising to the upper levels of the forest. They travel about in company with other small birds of the under-wood, such as the Slaty Antwren, Chestnut-tailed Automolus, and, at higher altitudes, the Stripe-crowned Warbler.
Although it is seen in most birds of the mixed forest flocks, they avoid other individuals of their kind beyond their own immediate family. They are not often found with army ants; were the application of the name “ant tanager” to this genus not sanctioned by long usage, it might be better to give it to the Gray-headed Tanager.
Voice
It is perhaps not wholly without significance that the two tanger’s that dwell in the undergrowth of the heavy forests of the valley of El General are less brilliant in plumage than most of the local representatives of their family and are here its most notable songsters. Probably where striking coloration serves to attract a partner, the song is reduced to a minor role in the advertisement of territory and the formation of pairs and tends to become poor and weak. Of the two forest-dwelling tanagers to which we here refer, the Gray-headed is the more appealing songster, but the Red Ant Tanager has the more varied repertoire.
He is, in fact, a vocalist with an amazing range of tones and moods, the most versatile that I know in the whole tanager family. Most of the ornithologists who have written briefly about the habits of the several species of Ha&a have commented on their loud, harsh voices. The loudest of the notes uttered by the Red Ant Tanager when surprised by man as it roams through the woodland are less harsh than those of some related forms, the Rosy-throated Ant Tanager, for example, and are mixed in incongruous fashion with softer and more pleasant calls.
On rare occasions, the male pours forth a softly warbled refrain of singular beauty, seldom long continued. A male which nest uttered low, sweet warblings as he came with food in his bill. Different again from all the other utterances of the ant tanager is his dawn-song, which came to know soon after my arrival in El General.
From late January until well into June this is one of the notable sounds of the awakening forest. His voice at this time is loud and clear, but scarcely liquid. Different individuals adopt slight variations of the same theme. One version of the dawn-song sounded to me like peter, peter, peter continued indefinitely at a uniform rate, with no separation into phrases to relieve the monotony of the insistent chant. Another ant tanager repeated interminably a phrase which called to my mind the word intervenes.
A third, as though to introduce a small measure of variety into his performance sang intervenes from 4 to 6 times without a pause, then rested momentarily before beginning a new sequence. Yet another sang peter-bird from 6 to 15 times continuously, with pauses of 8 to 10 seconds between series. In 1942 and 1943 an ant tanager sang each morning in the low, dense vegetation at the forest’s edge 50 yards from my house.
In a bright, crisp voice, and in a continuous flow without break or pause between phrases, he would sometimes seem to sing intervene. The monotonous song starts in the dim first light when the forest birds begin to waken and is continued tirelessly for many minutes until finally silenced by the growing daylight.
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This ant tanager, unlike some of his close relations, does not amount to a high and conspicuous perch to deliver his dawn-song but remains as always well concealed amid thick undergrowth, often near the forest’s edge. Accordingly, I have never enjoyed a really satisfactory view of him as he sang at dawn. The dawn-song is different in form and tone both from the usual chatter of the ant tanager as he roams through the forest and from his sweet warbled song that, until 1 heard it later in the day, that it was an utterance of the same bird.
Like the dawn-songs of the flycatchers, which it resembles in the endless repetition of a single simple phrase, this song is rarely heard at a later hour, and then as a rule only when the birds are excited by rivalry or perhaps by an escape from sudden danger. When I overheard the notes of the dawn-song while the sun was high, there were usually several ant tanagers in the vicinity; and their sharp, excited calls left no doubt of their identity even when foliage screened them from view.
Sometimes heard a song intermediate between the dawn-song and the sweet warbling that in phrasing was like the former but in its soft tone approached the latter. While one male ant tanager gave the warbling song as he came to the nest with food in his bill, another voiced a subdued version of the dawn-song in the same circumstances.
Very different in form and in the position chosen for delivery, and far more melodious, was the dawn-singing of the ant tanagers that heard in the neighborhood of Colomba in the Department of Quezaltenango in western Guatemala. San Diego, about 3000 feet above sea level, the backs and sides of the long, steep ridges of volcanic soil were occupied by coffee groves; these were largely under the shade of tall trees left standing when the original forest was thinned to receive the coffee seedlings.
In the bottoms of the deep, narrow valleys were remnants of unspoiled forest, with much dense, impenetrable second-growth on the precipitous intervening slopes. In the lush vegetation of these humid ravines was a considerable population of both the Red and the Rosy-throated ant tanagers. However, in the remnant of the forest at the confluence of two rushing mountain streams, nine feet up in a sapling; found the slight, open nest of the latter, containing two eggs.
With these two rather similar species present, the identification of the males who sang so profusely, generally well above my head, was a matter of considerable difficulty; but so far as all Red Ant Tanagers, probably of the race salvadorensis. All through the day, the ant tanagers at the plantation lurked in the dense vegetation of the valley bottoms and lower slopes, where I sometimes heard their harsh chatter and more rarely saw them.
But at dawn, the males rose to the edges of the coffee plantations to sing, from an exposed perch some 40 or 50 feet up in a tall shade tree, or even from the topmost boughs. Now in July, Gray’s Thrushes were falling silent at daybreak; and the ant tanagers had the air almost to themselves, singing generously in a manner one would hardly expect from the musically deficient family of tanagers. Their song, lovely in its simplicity, consisted of from seven to nine loud, clear notes, with considerable pauses between the well-marked phrases; it was repeated at the rate of about eight times per minute.
While listened near one, from both slopes of the valley would hear the answering songs of other ant tanagers, all delivered in the same clear, far-carrying voice. There were considerable differences in the tone and phrasing of several individuals. The total effect was not that of a chorus so much as of a kind of responsive singing. While performing, the birds often spread their scarlet crown-patches, which shone out brightly even in the half-light of dawn. The full tide of music lasted about three-quarters of an hour. But the more persistent songsters continued for nearly an hour, usually staying on the same perch throughout this long period.
Toward the end of the protracted performance, their songs became more widely spaced; and by preening, scratching, and stretching wings and tail, they revealed that zeal was waning. Then, of a sudden, each would dive straight downward, almost seeming to fall, from the high tree top-down the steep slope to the dense vegetation in the ravine while their mates remained unseen. From far below a few scattered verses of the same song might then float up to me.
By a quarter to six, all had ceased their morning singing and rarely heard it again until the following dawn. The ant tanagers began to sing somewhat later than the thrushes, orioles, ground-chats, and sparrows, possibly because they ate a little before embarking on such a long vocal performance, more probably because in the dense vegetation in the deep, narrow valleys where they lived, daylight came a little later to awaken them. Chapman has given high praise to the song of the Dusky-tailed Ant Tanager, now considered to be the Isthmian race of the Rosy-throated Ant Tanager.
He wrote that “it was composed of sixteen highly musical, flute-like notes so exactly separated by the intervals of our scale that, judged even by human standards, they formed a true song.” But that he used to paraphrase this song as glad to meet you; and so it sounded to hear it at dawn. Probably the longer song mentioned by Chapman was formed by running together four of the basic phrases.
We heard a Rosy-throated Ant Tanager deliver this same song in the evening, which suggests that, unlike the Red Ant Tanager and most other birds with typical dawn-songs, but like the Streaked Flycatcher and the Wood-Pewee, this tanager sings in both the morning and the evening twilight.
Red ant Tanager “Habia rubica”
Male Red-crowned ant tanager “Habia rubica” Photo Credit – Wikipedia
The Nest
In the valley of El General the breeding season of the Red Ant Tanager extends from February until at least June. Here I have found eight nests, all in the primary forest, although sometimes in a bushy opening between the trees. All were situated in saplings or slender bushes, often such as were entwined by vines or climbing ferns, and at heights ranging from 5% to 18 feet above the ground. But the highest nest was exceptional, and 6 of the 8 were between 6 and 12 feet up.
The structure is a broad and usually shallow cup, composed of rootlets and fibers, those on the exterior coarse, those in the lining finer, all together forming a fabric so thin and open that the eggs are visible through the meshes of the bottom. Coarse strands of spider’s silk are used to bind the nest to its support, which is sometimes the trifurcation of a slender stem.
A typical nest measured 3 inches in internal diameter by 1% in depth. Once found a female ant tanager with fibrous material in her bill and saw her go to a nest she had newly begun. Later set up a blind and spent 3% hours watching, but I saw her bring material only four times more.
On each occasion, her loud, harsh notes announced her approach through the undergrowth before she could be seen. But she was silent while actually at work arranging the strands in her nest. Her mate did not appear. This nest was never completed, probably because the site chosen for it failed to provide adequate support.
The Eggs
From two nests the single egg was lost before the set was complete, and another contained a single nestling. Of complete sets, there were three of two eggs and one of three eggs. The eggs are dull white or have a faint bluish tinge and are marked with speckles and blotches of pale brown or cinnamon.
Also sometimes at chocolate spots are gathered in a wreath around the large end and sparingly scattered over the remaining surface. One had instead of definite spots a smoky brown band around the thick end: also were some faint grayish mottlings and a few very fine brown dots, with still fainter dots toward the sharp end. The average measurements of eggs are about 17.7 millimeters.
Incubation
Incubation is performed by the female only. Red Ant Tanager in the forest contained two eggs well advanced in incubation. Two days later the female was sitting to set the blind on the steep slope above the nest. She flew but soon returned to cover her eggs. An abrupt movement again from her nest, but she promptly came back to it in my presence. She incubates from daybreak until at the blind by rain and hunger.
Thus she incubated for more than 78 percent of the time, a good record for a tanager. After each excursion she chattered loudly as she settled on the eggs but thereafter she incubated in silence, sometimes preening as she sat. At times a thin strip of dull orange, narrowly bordered on each side by black, was visible along the center of her crown; but at other times these brighter feathers were all folded down and invisible, leaving only a narrow median line of black over her head.
Female Red ant Tanager “Habia rubica”
Female Red-crowned ant tanager “Habia rubica” Photo Credit – Wikipedia
The Nestlings
The newly hatched nestlings have pink skin sparsely shaded by long, dark-gray down, and their eyes are tightly closed. The interior of the mouth is red. The nest containing two nestlings that had hatched in the preceding night. Although the male sometimes accompanied his mate on her return to the nest, especially early in the morning, he always stopped short several yards from it and did not once go to look into it.
The pair would approach voicing loud notes in sharply contrasting tones, many of them harsh. The female exercised much patience in delivering food to her newly hatched nestlings, which seemed to experience difficulty in swallowing even the small larvae that were well crushed in her bill. Sometimes after trying for several minutes in vain to make the nestlings eat, she was obliged to swallow the food herself.
The following morning watch at this nest. The mother returned with a small larva, gave it to a nestling, and then brooded. Her mate followed her, bearing a large green caterpillar and uttering low, sweet warbling notes interrupted by loud, harsh calls. He approached to a point about three yards from the nest, hesitated there, and then went off with his caterpillar. The female brooded until flew away, and seven minutes later returned to feed and brood, again followed by her mate.
He then went off, but while the female sat he returned with a morsel and went to the nest. The mother flew away and standing by the nest he coaxed the nestlings to receive his offering. Since they would not take it he swallowed it himself, ate a dropping, and flew away. In the 3 hours of my watch, the female brought food 5 times.
The male came thrice with food, but only on his second and third visits went all the way to the nest with it, and both of these times he failed to deliver it because it was too big for the nestlings. Since my earlier watch had shown that his visits to the nest were at best infrequent, how did he discover that the nestlings had hatched?
The fact that when he first appeared with something in his bill he did not go up to the nest with it lends weight to the second supposition. He did not, like his mate, adjust the size of his offerings to the nestlings’ capacity; had she been as blundering as he, they might have starved because offered items that were too large. While at the nest, the only point where his bright scarlet crown patch quite folded under; or at most I caught a glimpse of brilliant color in the middle of the black median line.
The mother brooded the nestlings for 5 periods ranging from 9 to 3.5 minutes and totaling 89 minutes, with 4 completed absences ranging from 6 to 38 minutes. The two nestlings in the nest where incubation was 8 days old and studded with pin feathers. Although quite without expanded plumage to cover them, the nestlings were brooded only once, for 14 minutes, by their mother.
She brought food 17 times, the male 12 times, and there was one more feeding early in the morning when the light was so dim beneath the high forest trees that I could not see the parent’s color and determine its sex, making a total of 30 feedings, or 3 per nestling per hour. So far as I could see, the food consisted wholly of larvae and mature insects.
Many of the offerings were so big that the youngsters gulped them down with difficulty. One especially large insect was swallowed only after ten minutes of valiant efforts by the youngsters and their mother. Each time that one failed to swallow it, she took it again into her own bill and mashed it flatter, and the flatter it became the more its width exceeded that of the nestlings’ throats. Dozens of times it was given to a youngster only to be taken again into the mother’s bill for further treatment.
At last, one succeeded in laboriously gulping it down. Then it voided a dropping, which the mother carried away. With such substantial meals, the babies required few feedings; and the parents did not need to make many visits which might betray the nest’s position to predators. In approaching the nest, which was six feet up in a slender sapling, the parent tanagers flew low and came to rest on some support near the ground, to look carefully around before rising to its level.
This mode of approach was admirably indirect and revealed great caution on the part of the tanager’s; but at the same time they often, although not invariably, came, delivered the food, and flew off with much sharp chatter that would certainly have betrayed their position to any predator that hunted with its ears. Other types of predators must be abundant and efficient; for all my nests of the Red Ant Tanager were prematurely destroyed by them, and I was unable to determine the length of the nestling period.
Summary
Red Ant Tanagers occur in humid lowland forests and in Costa Rica range up to about 4000 feet above sea level. Never forming flocks of their own kind, they wander in pairs through the lower levels of the woodland, usually in company with a variety of small birds of other species. They seldom follow the army ants. These garrulous birds have a remarkable variety of notes.
Their calls, now harsh, now softer and more pleasant, are uttered almost incessantly as they wander through the forest. At times the male delivers a soft warble of singular beauty. At daybreak, he sings a special song seldom used later in the day except under the stress of great excitement.
This dawn-song consists of a simple phrase of two or three sharp, clear notes reiterated incessantly for the better part of an hour. This song usually is given from a low perch amid dense vegetation. In El General Nesting begins in the dry month of February, but the majority of nests are found after the rains begin in April, May, and June.
The open nest is placed in the forest undergrowth, usually in a slender sapling or bush, from 5% to 18 feet up. The two or sometimes three eggs are incubated solely by the female. One female took very long sessions, ranging from 88 to more than 142 minutes, and she covered her eggs more than 78 percent of an observation period of 7% hours.
The nestlings, which bear sparse natal down, are brooded by the female and they are fed by both parents. Two nestlings eight days old were fed 30 times in five hours of the morning. The food consisted of larvae and mature insects, many so large that the youngsters swallowed them with great difficulty. In approaching the nest, the parents always flew near the ground, well below the level of the nest. Read More – Distinctive Stripe-tailed Hummingbird
Reference – Life Histories of American Central birds by ALEXANDER F. SKUTCH
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