Do Antbirds Help or Hinder Army Ants? (Section 1: Background)
Some of the birds rely solely one species of army ant. "Using a hypothesis of the evolutionary relationships among antbird species that we. A massive swarm-raid by an army ant colony is one of the most But what exactly is the nature of the relationship between the ants and their. World birds follow marching swarms of army ants and capture arthropods flushed by the ants. . plumed Antbird (Pithys albifrons) trapped in a mist net at Manaus. However, the flocks in relation to ant-following birds at Belem, Brazil.
A further four species regularly attend swarms but are as often seen away from them. Obligate ant-followers visit the nesting bivouacs of army ants in the morning to check for raiding activities; other species do not. They generally details vary among species maintain breeding territories but travel outside those territories in order to feed at swarms.
Several pairs of the same species may attend a swarm, with the dominant pair at the swarm being the pair which holds the territory that the swarm is in. In addition to competition within species, competition among species exists, and larger species are dominant.
In its range, the ocellated antbird is the largest of the obligate ant-following antbirds and is dominant over other members of the family, although it is subordinate to various species from other families including certain woodcreepersmotmots and the rufous-vented ground cuckoo.
- Ant follower
At a swarm, the dominant species occupies positions above the central front of the swarm, which yields the largest amount of prey. Smaller, less dominant species locate themselves further away from the centre, or higher above the location of the dominant species, where prey is less plentiful. In most species the pair defends a classic territoryalthough the nesting territories of ant followers are slightly different see feeding above.
Territories vary in size from as small as 0. Ocellated antbirds have an unusual social system where the breeding pair forms the nucleus of a group or clan that includes their male offspring and their mates.
These clans, which can number up to eight birds, work together to defend territories against rivals. Pair bonds are formed with courtship feedingwhere the male presents food items to the female.
One dominant pair may share a territory with up to six other birds.
Section 2: What is the relationship between ant-following birds and army ants?
The nesting and breeding biology of antbirds have not been well studied. Even in relatively well-known species the breeding behaviour can be poorly known; for example the nest of the ocellated antbird was first described in Antbird nests are cups of vegetation such as twigs, dead leaves and plant fibre, and they follow two basic patterns: Supported nests rest upon branches, amongst vines, in hollows, and sometimes on mounds of vegetation on the ground.
Each species nests at the level where it forages, so a midstory species would build its nest in the midstory. Closely related species nest in the same ways. For example, antvireos in the genus Dysithamnus are all suspension nesters. Small clutch sizes are typical of tropical birds compared to more temperate species of the same size, possibly due to nest predation, although this is disputed.
The length of time taken for chicks to hatch is 14—16 days in most species, although some, such as the dusky antbirdcan take as long as 20 days. The altricial chicks are born naked and blind. Both parents brood the young until they are able to thermoregulatealthough, as with incubation, only the female broods at night. Both parents feed the chicks, often bringing large prey items.
When the chicks reach fledging age, after 8—15 days, attending parents call their chicks. As each chick leaves the nest it is cared for exclusively from then on by the parent that was present then.
After the first chick fledges and leaves with a parent the remaining parent may increase the supply of food to speed up the process of fledging.
After fledging, chicks spend the first few days well hidden as the parents bring them food. Chicks of some species may not become independent of the parents for as long as four months in some antwrens, but two months is more typical for the rest of the family. Ecology[ edit ] Antbirds are common components of the avifauna of some parts of the Neotropics and are thought to be important in some ecological processes.
They are preyed upon by birds of preyand their tendency to join flocks is thought to provide protection against such predation.
Section 1: Design an Experiment
It has been suggested that the depressive effect of this parasitism slows the development of E. The ant-following antbirds are themselves followed by three species of butterfly in the family Ithomiinae which feed on their droppings.
Status and conservation[ edit ] The pectoral antwren of Brazil is threatened by the loss of deciduous forest and is listed as vulnerable by the IUCN. As of April38 species are considered by the IUCN to be near threatened or worse and therefore at risk of extinction.
The fragmentation of forests into smaller patches affects species that are averse to crossing gaps as small as roads. If these species become locally extinct in a fragment, this reluctance to cross unforested barriers makes their re-establishment unlikely.
Smaller forest fragments are unable to sustain mixed-species feeding flocks, leading to local extinctions. An unplanned experiment in fragmentation occurred on Barro Colorado Islanda former hill in Panama that became an isolated island during the flooding caused by the creation of the Panama Canal. Numerous species of antbird formerly resident in the area were extirpatedin no small part due to increased levels of nest predation on the island.
Antbird - Wikipedia
The majority of threatened species have very small natural ranges. Foraging workers carrying off small insects and gang up on and overwhelm larger animals by sheer numbers. Many insects and other animals flee ahead of the advancing swarm.
Workers use their bodies to create living bridges to overcome obstacles, and at night, form a living shelter for the queen and brood. As these huge colonies move through the forest, they are often accompanied by a community of other species, including birds, other insects, lizards, and even mammals Schneirla But what exactly is the nature of the relationship between the ants and their followers?
Do they help or hinder the ants? Most army ants are in one of two genera: Dorylus paleotropics and Eciton neotropics. The army ant lifestyle includes nomadism usually the whole colony movesgroup predation raidsand, often, above-ground nesting. Although ants in other genera have these behaviors, the extent to which they are developed and combined is unique to the "true" army ants Gotwald An army ant colony typically cycles between two behavioral phases: During the nomadic phase, a colony moves daily, housing the queen and brood in a temporary bivouac, and conducts large foraging raids.
During the statary phase, the colony stays in one place for several weeks and conducts small-scale raids during the day. The main prey of a raiding army ant colony are leaf-litter invertebrates and the brood of other social hymenoptera ants, bees, and wasps. Workers usually aggregate on prey, collectively subduing and dismembering it Gotwald As a result, army ants can capture prey many times larger than an individual worker.
Because army ants will attack almost anything, many animals flee the oncoming swarm.