Some animals have non-linear hierarchies, where one individual dominates others but he himself can also be dominated. In contrast, dominance hierarchies in black-capped chickadees are linear, where one individual dominates all the others; a second dominates all but the first, and so on. Aaron Harvey ’17 is carrying out a project at the Vassar Farm and Ecological Preserve (VFEP) to establish hierarchies of the resident chickadee populations. Determining who is dominant and who is submissive between two chickadees requires designating a “win” and a “loss.” Behaviors such as chasing another bird away from a feeding station, resisting an attack, or obtaining a submissive reaction from another bird count as “wins.” Measuring wins as a percent of total interactions can help determine dominance rank. We are doing this by reviewing videos taken by a mounted Kodak Pixpro of chickadees interacting at feeding platforms. Potential dominance behaviors we are looking for include:
The black-capped chickadee on the right elicits a submissive reaction from the one on the left, who turns away from his opponent. (AP Photo/Mark Duncan)Supplants: One bird forces another off the platform
- Resisting a Supplant: One resists being forced off the platform by another
- Submissive Posturing: While a bird eats, another faces its head away until the first finishes
- Waiting: One bird waits on the platform until the first has finished feeding
Jack Blomberg ’18 holds chickadee for the first time
