Rufous Tailed Hummingbird

The rufous-tailed hummingbird (Amazilia tzacatl) is a medium-sized perky, active and aggressive species that occurs in a variety of habitats. It prefers open scrubby areas, gardens and plantations. It regularly visits nectar-feeders.

It forages for nectar on many types of flowering plants; Hamelia, Heliconia and Cephaelis. Males vigorously defend foraging sites. Studies by University of Missouri researchers show that aggression by males tapers off if intruders vastly outsize the combative individual. Smaller intruders are vigorously attacked. Studies show that if males of this species perceive the local food resources are extensive; their combative enthousiasm becomes more acute.

Males are extraordinarily vocal, some singing all day virtually non-stop. The call is shrill, raspy and often metallic, sometimes repeated in bursts.

Up to 200 wing beats per second!

Research in Costa Rica shows that these hummingbirds often become entangled in spider webs (sometimes fatally). They are apparently drawn to the webs by entrapped insects upon which they sometimes feed. This species also sometimes collides with windows.

Researchers confirm the rufous-tailed hummingbird can vary the frequency of its wing beats according to the type of flower upon which it is foraging. Hovering above large-diameter flowers takes much more energy because wing beats increase to compensate for reduced wing beat amplitude. About 10 percent less energy is needed for foraging on small-diameter flowers. The normal wing beat rate is about 70 beats per second, with beat of up to 200 per second during aerial displays. Wing muscles make up about 25 percent of the total body weight.

This species occurs over a large area, from Mexico to Colombia. It is common throughout its range and is the most abundant hummingbird in Costa Rica.

Rufous-tailed hummingbirds are just over four inches in total length. The female is solely responsible for rearing offspring. The nest is a tiny cup, usually located on a narrow horizontal branch. Two white eggs are incubated for about 16 days. The fledging period is 20-26 days.

This species occurs regularly at Selva Verde and in the surrounding countryside. It is a tame species, easily approached, often frequenting the gardens near the cabins.

This hummingbird has considerable geographic variation resulting in at least 5 different subspecies. More are likely to be discovered, researchers say, owing to the diversity of habitats where the bird is found. So far, the subspecies are; A.t. tzacatl, A.t. handleyi, A.t. jucunda, A.t. fuscicaudata and A.t. brehmi.

- Robert Alison, PhD
Robert is an avian ecologist and ornithologist based in Victoria, British Columbia. He is a frequent contributor to Field Notes.

Golden-hooded Tanager

The golden-hooded tanager (Tangara larvata) is among the most striking of the neotropical tanagers, a group of more than 200 species, most with extraordinarily colorful plumages. In common with most other tanagers, this species is not a proficient songster and its vocal repertoire comprises a few coarse rattles and a sharp ‘tsit’.

This tanager, sometimes called ‘golden-masked tanager’, is common in the Selva Verde area, where it occurs primarily in the upper forest canopy and in clearings. However, pairs and small flocks often can be seen in gardens and at fruit feeding stations, where bananas seem to be a particular favorite item. They occur regularly on the Selva Verde grounds.

The main diet is fruit and seeds, particularly Ficus and Cecropia, and sometimes insects are eaten as well. In Costa Rica, up to 98 percent of fruiting trees depend on wildlife to disperse their seeds; seed dispersal is achieved through fruit ingestion and defecation. Research shows these tanagers are among the 5 most-important avian seed dispersers in Costa Rica. Collectively, they remove up to 16 percent of the fruit from primary fruit-producing trees.

These tanagers nest mainly from March to September. Pairs construct small cup-like nests, 5-90 feet above the ground, often in banana trees or in the forks of sub-canopy trees. Two heavily-blotched white eggs are incubated by the female for about 14 days. The young fledge in about 18 days. Usually, breeders produce two broods per year.

Golden-hooded tanagers engage in ”cooperative breeding”, a phenomenon in which offspring from previous broods assist their parents in rearing the young of subsequent broods. Research in Costa Rica confirms two or more breeding birds are assisted in brood-rearing by one or more ‘helpers-at-the-nest’. Some are ‘primary’ helpers that are offspring from previous broods of the breeding pair; others are ’secondary’ helpers that are unrelated to the breeding pair, usually non-breeding males. All helpers deliver food to nestlings.

Cooperative breeding is fairly common in neotropical birds and is a good example of ‘group parenting’ strategies. Researcher at La Selva shows that such a strategy significantly boosts nestling survival and growth rates. But, so far, preliminary genetic testing has failed to confirm whether or not proficiency in helping behavior is an inherited trait. Nonetheless, offspring from socially dominant pairs tend to be better helpers-at-the-nest, compared with offspring from subordinate pairs.

This tanager species often associates with other fruit-eating sparrow-sized birds in mixed foraging flocks. At Selva Verde, such flocks typically comprise other tanger species, as well as euphonias and honeycreepers that move across the canopy in loose harmonious groups.

- Robert Alison, PhD
Robert is an avian ecologist and ornithologist based in Victoria, British
Columbia. He is a frequent contributor to Field Notes.

Lots of these birds stop in Costa Rica, but many continue south. Some travel as far as the Patagonia in Argentina.

Best Time to see them

Our skies are full of these migrating birds heading down south from late July until early November, with the most intensity during October. Around 3 million migrating birds (Hawks, Kites, Falcons, Osprey, Turkey Vultures, and others) pass by our country in this period.

March and April are ideal to see birds heading back up North.

On January 8th 2009 an earthquake that registered 6.2 on the Richter scale shook Costa Rica. Fortunately the earthquake did not do damage to our forest, lodge or town, but it did affect the sustaining pillars of our cable suspended bridge leading to our primary forest. Although we worked hard to strengthen the pillars, a few miles upstream a huge tree made a natural dam that grew daily. A few weeks after the quake, heavy rains caused the natural dam to break causing a huge wave bearing rocks, trees and anything that was on its way. With our weakened pillars this mountain of debris brought the bridge down.

Short-billed Pigeon

The pale-vented pigeon (Columbus cayennensis) is one of 285 species of pigeons and doves that occur virtually all over the world, except Antarctica. Smaller species tend to be known as doves; larger ones are pigeons. Most have soft subdued coloration, often punctuated with metallic iridescence on the neck feathers. Some are strictly arboreal; others forage mainly on the ground.

The pale-vented pigeon is a smaller-sized bird which is widely distributed in Costa Rica, and is a permanent resident. It is quite common, especially at lower elevations (up to about 2000 feet).

Extensive migrations usually occur in some pale-vented pigeon populations, and sometimes migrants penetrate into Costa Rica, mainly from November to May.

These are mainly arboreal birds, which forage for berries and small fruit in trees and shrubs, especially Trema and melastomes. Various fruit-ripening chronologies cause foraging pigeons to relocate feeding activities frequently. Ficus are favorite food items, and flocks of 12 or more often congregate high in the forest canopy, focusing on the taller Ficus (fig) species.

Although these pigeons have a penetrating ‘coo-woo’ vocalization, often repeated in 2 syllables, they forage in silence. Calling typically takes place from an elevated and often exposed perch.

Forest edges are the best places to see these pigeons, but they also frequently occur in pastures, palm plantations and along rivers. They tend to avoid thick mature forests.

These are often very shy birds, typically avoiding close proximity to humans. But, in some more isolated areas, they can be quite approachable, especially at foraging sites.

They have an extensive total range, from Mexico to Peru. The population is estimated to be in excess of 50 million. Taxonomists have concluded this species has no very close relatives, but that it might be an intermediate between the band-tailed pigeon (C. fasciata) and the red-billed pigeon (C. flavirostris), both of which occur in Costa Rica.

There are five geographic subspecies: P.c. pollidicrissa (Mexico to Colombia), P.c. andersoni (Ecuador, Brazil and Venezuela). P.c. tabagensis (Trinidad), P.c. cagennensis (Guiana) and P.c. sylvestris (Peru to Argentina). Pale-vented pigeons are sometimes placed in the genus Patagioenas rather than Columbus.

The nest is a flimsy cup of twigs, usually 3-50 up in a shrub, small tree or palm. The birds occasionally nest on the ground. One white egg is incubated by both parents, female at night, male during the day. The incubation period is about two weeks and the nestling leaves the nest in about 14 days.

Nesting usually takes place near where the male-parent was reared; males are generally sedentary. Banding studies show that females are much more mobile than males.

Robert Alison, PhD
Robert is an avian ecologist and ornithologist based in Victoria, British Columbia. He is a frequent contributor to Field Notes.

Rufous Motmot

The rufous motmot (Baryphthengus martii) is the largest of six motmot species in Costa Rica; three others occur elsewhere. Motmots typically have short broad beaks, often decurved, and striking plumage coloration. There is no significant sexual dimorphism.  All motmots in Costa Rica  have two elongated central tail feathers; racket-tipped because loosely-attached barbs upshaft fall off, leaving much of the shaft itself bare.

These are mainly solitary birds, sometimes occurring in pairs, which usually perch inconspicuously in shade, with the tail swinging frequently like a pendulum. Foraging involves aerial sallying from a perch, capturing insects and plucking fruit from foliage.
The rufous motmot is an important seed-disperser. Studies confirm the fruit-digestion process is so rapid that fruit seeds are excreted intact and scattered on the forest floor, often far from the parent fruit trees. Forest regeneration thereby ensues.
These motmots sometimes eat poison dart frogs, seemingly immune to their deadly toxins; one poison dart from carries enough lethal toxin to kill ten humans. Researchers have documented that pair members sometimes capture poison dart frogs and feed them to each other.

Rufous motmots are widely distributed from Honduras to Ecuador and Brazil. According to BirdLife International, the species is  of “least” conservation concern, occupying a total range of over one million square miles. This species adapts readily to local conditions, a trait that has permitted it to thrive under a variet of environmental circumstances, even in close proximity to humans.
These are large (18 inches long) and robust birds, usually frequenting humid forests and shady thickets, often occurring along forest edges. They are very vocal; their melodious repertoires include a variety of rolling ‘hoots’.

Nesting takes place in a chamber at the end of a long (12-16 feet) tunnel excavated by both parents, usually in a stream bank or gravel pit wall. Both sexes alternately incubate the 2-5 eggs for 18-22 days. The young fledge in 24-31 days.
Motmots are typically quite shy and owing to their characteristic aloofness, patience is often needed to locate them, especially in thick vegetation. They sometimes frequent the margins of a small creek that flows through the Selva Verde property, or along the Sarapiqui River. Despite their bright coloration, they are remarkably difficult to detect.

Taxonomists are not agreed with regard to this species; some believe it is conspecific with the rufous-capped motmot (B. ruficapillus).

- Robert Alison, PhD
Robert is an avian ecologist and ornithologist based in Victoria, British
Columbia.  He is a frequent contributor to Field Notes.

Slaty Tailed Trogon

The slaty-tailed trogon (Trogon massena) is one of 40 species of trogons with similarly compact bodies, arboreal habits and colorful plumages. Most are sedate and characteristically perch upright, with the tail almost vertically downward. The flight is typically undulating, with brief spurts of rapid wing beats, and is silent. The birds perch in one location, rarely hopping or stepping from branch to branch; the feet are small and appropriate only for stationary perching.

They are among several trogon species that regularly occur at Selva Verde, often observed in clearings close to the guest lodgings and dining room, especially early in the morning. They are obligate frugivores, although they sometimes eat insects, and might even consume small lizards on occasion. They focus their foraging activities in the upper and middle levels of lowland forest, where they are especially fond of ficus and palm fruits. They often frequent the fig trees at Selva Verde.

They characteristically feed by sallying out from perches and delicately plucking fruit from the tips of twigs, usually without alighting, then return to a nearby perch.

These are mainly solitary birds, except during the breeding season. They tend to perch motionless for long periods, and finding them in thick foliage is often challenging. But, at times, they perch on exposed and usually vertical branches, in plain view. Otherwise, despite their striking colors, they are not easy to discover in the shadowy foliage where they typically occur. Their main call is a steady unmelodious barking, distinctly throaty and raspy; these birds are often heard before they are actually seen.

Slaty-tailed trogons are fairly common in much of Costa Rica; their main range extends from southeastern Mexico to Ecuador.

They nest at Selva Verde. Both members of pairs cooperatively excavate a nest chamber, at the end of an ascending tunnel, often located in the trunk of a decaying tree, wasp nest or epiphyte clump. The entrance to the nest is usually 8-50 feet above ground, and at Selva Verde, some nest as low as 15 feet above ground level. Females lay three eggs, which are incubated for about 18 days, by both parents in alternating shifts: female by night, male during the day. Young usually fledge in under 30 days.

Recent research confirms these trogons are important dispersers of forest seeds, some of which are regurgitated, some excreted, intact. In common with other frugivorous birds, their role in fruit-seed dissemination makes them important elements in the Costa Rican lowland forest.

These trogons tend to be quite tame and approachable, and they are often encountered only a few yards above the ground. The sexes are dichromatic; the males are much more colorful than the females. They are readily distinguished from the very similar lattice-tailed trogon by virtue of their orange beak; the beak of the latter species is yellow.

- Robert Alison, PhD
Robert is an avian ecologist and ornithologist based in Victoria, British
Columbia. He is a frequent contributor to Field Notes.

Red-Lored Parrot

Sonographic analysis shows that many local vocal dialects occur within the total range of the species. These dialects are distinct and reflect the general reluctance of these parrots to venture far away from their home areas; consequently geographic vocal variance occurs within subgroups. The vocalizations are innate, but parrots that do venture into new areas rapidly learn the dialects they encounter and thereby avoid being shunned as outsiders.

Red-lored amazons (Amazona autumnalis) are about 14 inches long; the striking plumage is mainly green with red speculum, forehead and lores.

These are vigilant birds, and often quite nervous, spooking noisily at the approach of human or other intruders. But, in the Selva Verde area, most are quite approachable–except in the vicinity of nests. Recent studies confirm that one of the most critical factors contributing to the breeding success of this species is its overall shyness and wary aloofness, and in particular, its inconspicuousness around the nest site. Such behavior minimizes the chances that a nest will be discovered, and potentially destroyed by predators.

Parents approach nests stealthily and silently, often perching for long periods in distant trees before actually flying to the nest itself. As an added precaution, young are fed only twice daily: about 30 minutes after sunrise and about 90 minutes before sunset. If danger is present, parents often skip feeding bouts and studies show that young of this species are capable of going without food for up to 36 hours with no apparent physiological or nutritional problems. It is the price they pay for their parents’ diligence in not disclosing the nest-site location.

Nests are typically located in cavities high up in the trunks of tall, usually dead, trees, most frequently palm trees. The usual clutch size is 3-4 eggs which are incubated for about 26 days. Normally, the female-parent is solely responsible for caring for the young for the first 10 days after hatching; thereafter, the male-parent assists. The age of maturity in this species is about five years; the lifespan can reach 75 years.

Red-Lored Parrot

Communal roosting is a characteristic behavior of this parrot, and recent research confirms a high degree of fidelity to roost sites, which are selected on account of their safety features. Some roosts host up to 800 of these birds. One study confirmed that pairs are much less likely to use their regular roost-sites during the nesting season, but that in the non-breeding period, counts at roost-sites provide a reliable estimate of the local red-lored amazon population.

These parrots prefer semi-open areas, forest edges and agricultural land; they tend to avoid large expanses of thick forest. They range from Mexico to Ecuador and Brazil, and within that range, there are four subspecies.

At Selve Verde, it is often most productive to look for red-lored parrots early in the morning, when pairs or small groups usually fly overhead and often perch to forage for fruit and seeds in nearby trees. They prefer palms, figs, legumes as well as some cultivated fruits (mangoes and citrus), as well as leaf buds.

In Costa Rica, there is a long history, among local residents, of keeping these parrots as household pets. They are considered family members and roost in the family living area; they are rarely kept in cages

- Robert Alison, PhD
Robert is an avian ecologist and ornithologist based in Victoria, British
Columbia. He is a frequent contributor to Field Notes.

Keel-Billed Toucan

The keel-billed toucan (Ramphastos sulfuratus) is a spectacular species with a preposterously over-sized bill, and one of the most recognized of all neotropical birds. Measuring 20-25 inches in body length, it is one of the larger toucans.

Its rainbow-colored banana-shaped bill is its main distinguishing feature. The structure is actually hollow and comparatively weightless, its keratin skin shaped by slivers of bone. Despite its large size, the bill is used with great dexterity, to toss food items into the air; the head is then flipped upward so the food falls into the mouth. The main diet comprises fruit, the seeds of which are excreted whole; consequently, this toucan is an important disperser of forest seeds.

These birds are clumsy flyers, with rapid wing strokes interspersed with gliding. Since they are so awkward in flight, they tend to avoid being too far from cover. The forest canopy is where they are most likely to occur, often perched on leaf-less uppermost branches.

These are extremely social birds, usually encountered in groups of 6-12. Each group comprises an adult pair accompanied by several generations of offspring. These groups troop through the forest, foraging together. At night, they nest together in a cozy bundle, huddled together communally in a single chamber, usually a natural tree cavity or woodpecker hole. Such cavities are cramped, but the birds tuck their bills under the wings, and the tails are elevated, to conserve space.

Despite their spectacular appearance, these toucans have comparatively unimpressive vocalizations; mere frog-like croaks and dry rattles.

Much fundamental keel-billed toucan ecological research has been done in the Selve Verde area. Researchers found that the birds next high up in natural cavities or woodpecker holes located  on smooth branchless tree trunks. Adults are exceedingly wary of intruders in the nest site area and regular disturbance can cause nest desertion.

Researchers confirm both parents incubate the 1-4 eggs, averaging about 15 minutes per session. Incubation takes 16-20 days. The young fledge in about 9 weeks, but can remain with the parents for several years. Maturity is reached after about three years and the lifespan is about 20 years.

The entrance to the nest cavity is only about 3 3/8 inches in diameter, so adults much squeeze energetically and awkwardly through to enter.

These birds spend about 40 percent of their time foraging for food, seeking not only fruit but also insects, small lizards and bird eggs.

Pairs are monogamous and infidelity is apparently quite rare. Sometimes frisky males engage is bill-duels, the function of which is not clear.

Keel-billed toucans are commonly seen at Selva Verde, regularly foraging in ficus (fig) trees and shrubs. Early morning and late afternoon is the best time to see them.

- Robert Alison, PhD
Robert is an avian ecologist and ornithologist based in Victoria, British
Columbia.  He is a frequent contributor to Field Notes.