Crested ibises and little egrets: Mixed-species flocks benefit both birds.

A crested ibis in flight. Photo: Shutterstock

The crested ibis is an endangered bird local to China, and was thought extinct until seven of them were discovered in 1981. Since then, they have made something of a comeback, but they still face many challenges. According to a recent study by researchers at the Beijing Forestry University, part of the way they deal with those struggles is by living among other birds.

The study looked at crested ibises flocking on their own, as well as those who flocked with Little Egrets. They found that the two birds, despite having different modes of foraging, work well together. Egrets are more visually focused than ibises, looking for food while ibises forage by feel. But the egrets notice danger more quickly because of their visual focus, which tips off the ibises among them.

This type of mixed-species flock is relatively common in birds. It has benefits, but it can also expose birds to diseases they might not otherwise face. Mixed-species flocks could also pose an interesting question for conservation practices. Those that focus on habitat conditions that favor mixed-species flocks may reduce the perception of risk by ibises, allowing them to breed and live more comfortably. This in turn would give them access to more habitats.

“Mixed-species flocks are such a common occurrence in birds, but little is known about the costs and benefits of joining such groups when species differ in their foraging tactics,” said the University of Montreal’s Guy Beauchamp, an expert on group living in birds. “In this case, ibises benefited from joining another more visually oriented species in that they detected threats more quickly. This study shows how detailed behavioral observations can help us understand why species forage in groups and also join other species.”

Of course, in order to do so we need more research on mixed-species flocks, in order to understand how they function, and what is needed for a given species to spend time in a given habitat, without competing too much with other species. Maintaining such habitats would be a matter of carefully balancing the needs of one species with those of another, which isn’t always going to be easy.