Researchers show for the first time how birds from two different species recognize individuals and cooperate for mutual benefit
Cooperation among different species of birds is common. To ward off predators, some birds build their nests close to those of larger, more aggressive species. Additionally, mixed-species flocks form enduring alliances to defend territories and forage together. However, these alliances are typically not between particular members of the other species; any bird from that species will do.
However, researchers from the Universities of Chicago and Nebraska demonstrate in a recent study that was published in the journal Behavioral Ecology how two distinct species of Australian fairy-wrens not only recognize individual birds from other species but also establish enduring relationships that support them in their collective foraging and defense of their shared area.
“The discovery that these two species are associated was not unexpected, given the widespread observation of mixed-species flocks of birds,” stated Allison Johnson, PhD, a postdoctoral scholar at the University of Nebraska who carried out the research for her dissertation at the University of Chicago. However, we recognized that this was extremely unusual when we discovered that they were only aggressively reacting to strangers and sharing territories with particular people. It fundamentally altered our investigation, and we realized we had to look into it. “.
Within Australia are two small songbird species: the splendid fairy-wren and the variegated fairy-wren. Each species’ males are well-liked by bird watchers due to their eye-catching bright blue feathers. Their behavior also makes them an appealing subject for biologists. Both species breed at the same time of year, consume insects as food, and live in large family groups. They also don’t migrate; instead, they spend their entire lives in the same eucalyptus scrublands, which are abundant in bushes and trees that provide cover.
The two species communicate when their respective areas overlap. They travel and forage together, and they appear to be aware of each other’s movements. They also help each other defend their territory from rivals. Both splendid and variegated fairy-wrens will defend their common area from outsiders, and splendid fairy-wrens will do the same while warding off unfamiliar birds from both species.
Given how similar their preferences for habitat and behaviors are, we would anticipate that splendid and variegated fairy-wrens would compete with one another. Rather, individuals of the two species have stable, positive relationships with one another,” stated Christina Masco, PhD, a UChicago graduate student and co-author of the recent paper.
Many songbirds use the distinctive songs that each bird sings to identify familiar members of their own species. But according to the researchers’ findings, this recognition happened across species. How could they be so certain?.
Johnson, Masco, and their previous advisor, Stephen Pruett-Jones, PhD, an associate professor of ecology and evolution at the University of Chicago, conducted research on these species at South Australia’s Brookfield Conservation Park between 2012 and 2015. Johnson’s first unexpected finding was that when he played a recorded vocalization of one species, the other species would react by taking off to see what was happening.
In order to confirm this finding, the researchers kept an eye on both species of fairy-wrens in the dark before sunrise and recorded their distinctive melodies. They play out the recorded songs on a speaker after sunrise, simulating an intruder bird entering a group’s domain. The idea was to observe the responses of territory owners to the songs of known and unknown members of the other species.
The four individuals whose songs were played were: a co-resident or “friendly” fairy-wren who lived in the same territory; a neighbor who lived nearby; an unidentified bird who lived five or more territories away; and a red-capped robin, a common species in the park that doesn’t pose a threat to the fairy-wrens. The researchers placed a speaker approximately thirty meters away from the subject fairy-wren.
Despite the species difference, both magnificent and variegated fairy-wrens showed that they could identify the songs of their fellow residents. Compared to friendly birds sharing their territory or the red-capped robin, socially dominant males of both species reacted more aggressively to the songs of strangers and other fairy-wren species. They did not react when they heard the songs of friendly birds, indicating that they did not consider them to be a threat.
Fairy-wrens are better able to protect their territories from competitors and their nests from predators when they establish and maintain these relationships with other species. Evidence suggests that communicating with other species offers advantages beyond just protecting one’s territory. The variegated fairy-wrens were less watchful, spent more time foraging, and had greater success raising their young than the splendid fairy-wrens, who did not alter their behavior when interacting with other species.
According to Johnson, Masco, and Pruett-Jones, the fairy-wrens cooperate with the other species by associating with them. These naturally gregarious species form larger groups to help defend their territories and fend off invaders by interacting with other species that share the same territory rather than working against them. In other words, if you cant beat em, join em.
Pruett-Jones stated, “Even though it was surprising to find that individuals of different species can recognize one another, it is likely that something similar occurs whenever species of non-migratory birds live on overlapping territories.” Since recognition promotes sociality within species, it stands to reason that it would also promote relationships between species. “.
Story Source:
Materials provided by University of Chicago Medical Center. Note: Content may be edited for style and length.
Journal Reference:
- Allison E Johnson, Christina Masco, Stephen Pruett-Jones. Song recognition and heterospecific associations between 2 fairy-wren species (Maluridae). Behavioral Ecology, 2018; DOI: 10. 1093/beheco/ary071 .
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Keeping an eye on your backyard bird feeder will help you become more aware of the variety of birds that call your neighborhood home. You might wonder how the various birds coexist as you watch them come and go, given their distinct colors, sounds, and behaviors—especially in light of the birds’ territorial nature.
While certain bird species coexist peacefully and ignore one another, others collaborate. For instance, a chickadee may fly by and pick up the insects that were agitated during the woodpecker’s attempt to remove the bark from a tree in search of grubs. Additionally, if a chickadee detects a predator, woodpeckers react to its alarm call. Chickadees, woodpeckers, titmice, and White-breasted Nuthatches will form flocks in the winter to search for food.
While not all birds flock together, there are several benefits for them to do so. Predators are far more likely to be confused and distracted by their sheer numbers. Thus, there is a certain level of security when foraging in a group. Additionally, as the paragraph above taught us, occasionally they find a source of food for each other.
The short answer: It depends. One thing to think about is the resources that are involved and if the birds have the same interests. For instance, different bird species, such as tree swallows and blue birds, can coexist peacefully and raise their broods next to each other if you attach two nesting boxes on the same post. But remember, you will still witness them fighting off intruders of the same species!
FAQ
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