National Geographic
Menu

Studying the Largest Bird Nests in the World

Gavin Leighton is a graduate student at the University of Miami conducting studies among weaver birds in Africa to try to understand the evolution of their amazing societies. Along the way, experimental surprises and appearances by predators are almost inevitable.

My name is Gavin Leighton, and I thought it would be a good idea to give an overview of myself and my research before blogging from the field. I’m a graduate student at the University of Miami where I study social behavior and evolution. To investigate these topics, I perform field research on sociable weavers (Philetairus socius). These little guys are small birds that are native to southwestern Africa and are one of the only (possibly the only) bird species that builds a communal nest that a colony will inhabit for multiple years.

In the picture you can see the sheer size of these nests as I’m standing under one of them, and I stand at about six feet tall! I’m currently investigating whether punishment drives the cooperative nest construction behavior that is necessary for the maintenance of the nest. Why would cooperation have to be maintained? Well, selfish individuals that devote energy towards reproduction would be favored over individuals that devote time and energy towards maintaining this cooperative nest. In this case we’d expect the selfish behavior to outcompete the cooperative behavior, thus requiring evolutionary mechanisms that maintain cooperative nest construction.

Gavin Leighton Standing Under a Nest Made by Sociable Weavers
Me, standing under a nest made by sociable weavers. (Photo by Gavin Leighton)

We started up the project recently at the “BRinK” research camp and have run into some inevitable problems with field research. While we intended to observe cooperative nest construction of sociable weavers in an artificial field aviary, we slowly discovered that the sociable weavers we put in the aviary were content with eating the termites and seed we had provided them, and performed none of the behavior we were interested in measuring.

Therefore, we have switched to a typical observational study where we have placed color bands on free-living sociable weavers, and are in the process of cataloging the same behaviors that we intended to in the aviary experiment. In the days of experimentation so far, we have observed the behaviors we are interested in and have also seen some remarkable, unanticipated behaviors from other birds as well. For instance, two days ago we saw a Gabar goshawk (Melierax gabar) attempt to catch a sociable weaver on the wing as a large, foraging flock was coming back to the nest. We’ve also seen pygmy falcons (Polihierax semitorquatus) enter the nest in search of potential food and shelter.

Pygmy Falcon Flying into the Nest of Sociable Weavers
Pygmy falcon flying into the nest of sociable weavers. (Photo by Gavin Leighton)

While diverting course may seem hard, it’s allowed us to witness individuals building under natural settings. There are definitive benefits to observing individuals outside of experimental settings, including being able to sit in awe of the massive nests these birds create. The industriousness of these sociable weavers is fully on display when you see them next to a large nest that they have helped build.

Read More by Gavin Leighton