If you're a spicy little bird who needs to defend his territory, you'll probably do a lot of yelling. Unfortunately, yelling at your neighbors all day takes a ton of energy and time you could use on other important tasks, like looking for grubs or keeping your feathers in top form. It would be best to be judicious about when you yell and who you yell at, saving your breath for the really big threats and not having the same argument with your neighbor over and over again. A lot of territorial animals (including ovenbirds) are more aggressive to strangers who have wandered into their space than someone they are familiar with, a kind of behavioral discrimination known as the "dear enemy effect". 

There's more than just how well you know a potential interloper, though. Whether you're more aggressive to a neighbor or a stranger might depend on what you have to defend: if your territory is particularly rich in food, a neighbor who is constantly trying to steal your grubs may pose more of a threat than a stranger who might be just passing through. Additionally, if you had a really rough winter and aren't entering the breeding season at the top of your game, you may do the bare minimum of territory defense, no matter who the threat is. For aggression as well as other aspects of an animal's behavior, context matters, and our research directions probe into some of that context. We are investigating the effects of territory quality, carryover effects from wintering, and the duration of the relationship with the neighbor on behavioral discrimination in aggression. 

Since ovenbirds need their territories in order to breed, they have to be able to keep control of it to successfully raise their chicks. On the other hand, if they spend too much time on defense, they'll be an absent father and their chicks may not get enough food to grow well. With climate change causing higher mortality rates, modern ovenbirds may not have the same neighbors year to year as often as previous populations did. Global insect declines are changing what food is available for breeding birds, and habitat loss in their overwintering grounds will probably make it harder to have the strength to establish a territory. We hope our findings will help with understanding how the changing context of aggression will influence future populations of angry birds.