- Order: Gruiformes
- Family: Psophiidae
- Polytypic 2 Subspecies
Although adults are largely frugivorous, the young chicks are fed twice as many insects as fruit, but the proportion of insects gradually declines to become a minor part of the adult bird's diet.
Trumpeters are highly social birds, and spend their lives in cohesive flocks. The details of the behavior of Gray-winged Trumpeters are little studied, but probably are similar to the behaviors of the Pale-winged Trumpeter (Psophia leucoptera), which has been studied in southern Peru. Trumpeter flocks have a defined dominance hierarchy and consist of birds of all ages and sexes. Dominance is recognized by means of a highly ritualized "Wing-spread" display, during which subordinate birds face a dominant bird, lower their heads, extend their wings horizontally, and give a call similar to the high-pitched twittering call of trumpeter chicks. This display is given by birds of all ages and is most commonly given just after dawn, a period during which birds fly down from their roost and reestablish their social rank for a few minutes. The Wing-spread display exposes the secondaries, which are darker on juveniles, and makes the bird vulnerable to attack, and thus a low-ranking bird seems to show a higher ranking bird that it is younger and subordinate. Dominant birds often respond to the Wing-spread display with a "Wing-flick," in which the folded wings are swiftly lifted up and forward and then brought down again.
In Pale-winged Trumpeters, individuals under three months old preform the wing-spread to all individuals, but older birds generally display to individuals of the same sex, maintaining a within-sex dominance hierarchy.
Most of the day is spent roaming the forest understory in search of fruit and arthropods and patrolling the flock's territory. Should a flock detect a trespassing group of trumpeters, the flock will run very rapidly towards them. Sometimes the trespassers are chased off, but more likely the trespassers are caught and a fight ensues. While driving out trespassers, birds run towards birds of the same sex with their head down and their wings arched upwards and the primaries and secondaries drooping towards the ground, and proceed to alternately peck and then flap up and kick the intruding birds, ever after they have fallen down, until the intruder flees or fights back. This continues until the intruders are chased back into their territory. Males are more likes to fight, while females and juveniles often stand back and give the loud territorial trumpeting call. After the intruders are chased onto their territory, Pale-winged Trumpeter males in both groups will then make submissive Wing-spread and dominant Wing-flick displays and will even offer food to males of the other group. It is during this time that subordinate adult males will often switch between groups, but will return to his home group after a few weeks if he does not succeed in achieving a higher rank. It is thought that males do this to increase their chance of breeding, and as a result there is genetic mixing between groups.
Allopreening and Social Feeding
Pale-winged Trumpeters spend more time loafing in response to increases in their food supply, and forage more diligently when food is scarce. When food is abundant, groups move slowly, and stop often to preen and bathe and sun. Adult Pale-winged Trumpeters frequently solicit preening from each other by bowing their heads towards other adults, who then rapidly open and close their beak as they run it through the feathers of the head and neck of the receiving bird, removing parasites and dead skin. Juveniles will solicit preening from adults or other juveniles. It does not seem that rank explains the amount a bird solicits or receives allopreening.
Trumpeters will often use food socially, especially when it is abundant. Pale-winged Trumpeters have been observed picking up a piece of fruit or an arthropod and hold its head high and arch its wings and walk around repeating a single, medium-pitched call note. Adults of the same sex or juveniles will then lower their head and give the submissive twittering and the food-begging call. The feeding bird will hold the food above the begging birds for a few seconds to a few minutes before it is given to one of the begging birds. Instead of swallowing it, occasionally the recipient of the food will pass it back and forth with the food donor several times until one of them swallows it. Dominant birds will even beg for food from lower-ranked individuals, but if the lower-ranked bird does not give the food within a few seconds the dominant bird will snatch it away.
Play, both solitary and social, is common among trumpeters, and much of it seems to mimic territorial squabbles. Birds will peck and kick at leaves and twigs, jump up in the air and flap, and run with the head lowered and the wings arched. When more than one individual plays they often chase each other between pecking at objects and will even face off and peck at each other without hitting, after which the birds split up and chase other birds. Birds tend to play for only a few minutes at a time.
When night falls trumpeters fly 8-15 m up to roost in trees, and tend to spread out into different parts of the same tree or different nearby trees. Trumpeters roost in different areas each night.
Gray-winged Trumpeters live in small groups of roughly 3-15 members, and the group defends large year-round territories with stable boundaries from other groups, largely by means of territorial calls (see Vocalizations). In the related Pale-winged Trumpeter (Psophia leucoptera), territories were found to vary from 58 to 88 ha, with an average of 72 ha (Sherman 1995b). Trumpeters spend much of their day foraging and patrolling their territory, walking an average of 3.7 km per day in the case of Pale-winged Trumpeters. During conflicts over territory, the territorial call will be employed while chasing out intruders, who, after reaching their territory, give the territorial call in response. For more information on territorial conflicts, see the above section on Territorial Behavior.
Trumpeters generally roost in trees in different regions of their territory each night. The territorial call is given by roosting flocks starting two hours after sunset, and each group calls for one to two minutes. Birds call throughout the night at intervals of two and a half hours. Flocks that roost near each other will fly down to their shared territorial boundary and call vigorously at each other.
As all suitable habitat is usually occupied by one or another territorial group, it is extremely difficult for young trumpeters to start their own territories. This shortage of territories seems to help explain why trumpeters are cooperative breeders, as they may gain higher fitness by remaining in the home flock.
Territories are often quite large, as they must provide enough fruit to sustain the flock the whole year, even during the dry season when fruit may be less available. Territories often contain many different habitat types (see Habitat).
Although all members of a flock assist with raising young, only a few birds breed, typically the single dominant female and a few dominant males breed. Breeding is proceeded by a good deal of courtship (female choice) and intrasexual selection (male-male competition).
In the related Pale-winged Trumpeters (Psophia leucoptera), ritualized feeding is part of a trumpeter courtship (Sherman 1996). The dominant male feeds the breeding female, but only during the breeding season, and during this time nearly all the food given to her is given through the dominant male. Most of the food he gathers himself, but some of it he steals from lower-ranking males.
Copulation is almost entirely confined to the breeding season. In Pale-winged Trumpeters, copulation begins six weeks before the female begins to lay. Eason and Sherman believe that for the first four weeks copulation is unable to fertilize the eggs: it follows then that males become increasingly protective starting the 2 weeks before laying, as the female is like receptive from this time until 24 hours before the last egg is laid. The three dominant males will guard the female from all other males and attempt to interrupt each other's copulation attempts. The dominant male obtains two thirds of all copulations, but he is unable to prevent the two next highest-ranking birds from stealing the remaining third of copulations. The Beta and Gamma males obtained 3/4 and 1/4 of the remaining copulations, respectively. In this way, the amount of genetic material passed on is proportional to a bird's dominance status.
In Pale-winged Trumpeters, males and females spend 5-10 s engaging in what appears to be solicitation prior to mating (Sherman 1996). The female crouches down and presents her rump to the male, while he walks in a circle around her while she turns to keep her rump facing him, until he mounts her and they copulate. Conceivably much of the same information above true for Gray-winged Trumpeters.
Social and interspecific behavior
Trumpeters are very vocal about announcing potential threats. Upon encountering a terrestrial predator, such as a human, the closely related Pale-winged Trumpeter (Psophia leucoptera) gives loud squawks as alarm calls and flees into dense cover. The presence of a snake is announced with a special call, and all members of a flock will stand together near the snake while calling for a few minutes, while aerial predators are announced with a different call. See Vocalizations.
Often reliant on primates, such as spider monkeys (Aleteles), capuchins, (Cebus), and squirrel monkeys (Saimiri), and to a lesser extent guans and curassows (Cracidae) and toucans (Ramphastidae) to knock down fruit and some insects, but trumpeters also usually actively follow monkey troops. Often commensals of army ants, feeding on the insects they flush. See Food.
Likely depredated by a wide variety of mammals, raptorial birds, and large snakes. Felids such as the Jaguar (Panthera onca) and Ocelot (Leopardus pardalis) likely take adults, while nests are likely raided by primates and coatimundis. Humans are a significant source of mortality in some areas, as trumpeters are highly sought after for food.
The three trumpeter species are some of a very small number of polyandrous cooperative breeding birds. Since their flocks have a strict pecking order, the rank of an individual bird determines if it will be one of the few that breed, and all members of a flock assist with raising the offspring. Only eight other birds species are known to have this mating system where several males copulate with a single female and help to raise the young; these include the Tasmanian Native-hen (Gallinula mortierii), the Galapagos Hawk (Buteo galapagoensis), the Dunnock (Prunella modularis), and the Striped-backed Wren (Campylorhynchus nuchalis).
Much of the work done on trumpeter breeding has been done on the Pale-winged Trumpeter (Psophia leucoptera), but as the two species are very closely related much of the information is likely quite similar.
Mating and Courtship
It seems that trumpeters time their breeding so that the eggs hatch at the start of the rainy season, the time when insects and fruits become most abundant.
Nesting site selection
In Pale-winged Trumpeters, the dominant pair begins examining nest sites two and a half months before the clutch is laid. Most nest site are tree cavities that were originally excavated by other species such as parrots, thus providing some shelter from the rain. A roof does not seem to be needed: twice the Pale-winged Trumpeter has been recorded nesting in the crack where a tree trunk splits into two (Sherman 1995a), and Gray-winged Trumpeters will nest in a roofless cavity atop a snag of the tree Vouacapoua vouacapoua 13.5 meters up (de Mercey and Théry 1999). No nest is built within this wooden cavity.
Laying and Incubation
Trumpeters lay between two and four eggs, most commonly three. Eggs are all white, and are 56-61 x 46-50 mm in dimension. In one study in French Guiana between 1993-1997, all eggs (n=7) were laid in February or March (de Mercey and Théry 1999). Breeding records in the Guyana shield range from December to May: chicks in March in French Guiana (Tostain et al. 1992) and in February and April in Guyana (Haverschmidt 1985), an egg laying in December and May for a captive pair in Suriname (Haverschmidt 1963), and an adult male in breeding condition was captured in March near the upper Orinoco, Venezuela (Hilty and Brown, 1986). The Gray-winged Trumpeter has bred in captivity in two North American zoos, and it has been found out that the eggs are incubated for 28 days before hatching (Horning et al. 1988, Male 1989).
Trumpeter chicks are nidifugous and precocial and are born covered with a thick layer of down. The face and wings are a russet color, while the crown and back are dark gray. The underparts are cream-colored, and a black bib covers the throat and upper breast. A russet strip runs over the top of the head from the top base of the mandible to the back of the neck, and other reddish stripes run lengthwise down the back.
Chicks jump out of their nest box before they can fly, apparently to little ill effect, and begin begging for food almost immediately. The duty of chick feeding is shared by all members of a group, though some individuals feed the chicks more than others. Sherman found that in Pale-winged Trumpeters non-breeding females and the dominant male contributed somewhat less to feeding the chicks, but such information is not known for Gray-winged Trumpeters.
Chicks are reliant on older members of their flock for protection and feeding. By ten days they flight feathers begin to come in, and by six weeks they can fly short distances and look like small adults. For the first three weeks they rely on other birds for feeding, by week four they contribute 25% of their own food intake, and by three months they are self-reliant but continue to beg for some time.
Populations and Demography
There is no information related to topics such as age at first breeding, life span and survivorship, dispersal, or population regulation.
Potter, Arjun Brandreth. 2011. Gray-winged Trumpeter (Psophia crepitans), Neotropical Birds Online (T. S. Schulenberg, Editor). Ithaca: Cornell Lab of Ornithology; retrieved from Neotropical Birds Online: http://neotropical.birds.cornell.edu/portal/species/overview?p_p_spp=142996