Cornell University, Feederwatch.org does good work. They've upped the traditional bird and backyard feeder counts to add three types of behaviour, which I've often thought about!
I have only witnessed behaviour #1, displacement. The sweet chickadees flee quickly when the bigger birds arrive. Then, the changeover in spring, when the song birds and insect-eaters arrive results in more topsy-turvy displacement. Purple finches, pine siskin. The birds wait in the evergreen until it is there turn.
Mr Rose-breasted grosbeak is back. He was perched on the Catalpa tree. At one point he yawned! I don't know if he was looking for competition, predators or the Mrs., but he was fun to watch. He just arrived back this week.
Behaviour #2, mobbing, not so much. The red-wings seem to tolerate the grackles and cowbirds. They all scatter when the blue jays arrive! It settles out, I think, by size.
I don't see these guys mobbing, Behaviour#2. They seem to share pretty well, with much seed scattered by the larger birds who don't fit on the feeders well, and throw it all about!
Behaviour #3, predation, I snapped a photo one harsh winter, when I spotted the Sharp-shinned hawk. He's been chasing birds and with killing them, or having them smash into the window: a blue jay, grouse, both hit the window at great speed. Also, the small saw-whet owl had been taken out.
|Hawk chased this Grouse into the window|
To learn about what interactions are occurring at feeders, we built a behavioral observation input tool to gather data about three types of interactions:
1) displacement, where one bird causes another to relinquish its position near a food source;
2) mobbing, where one or more birds harass another;
3) predation, where one bird attacks and eats another.
I kept meaning to look into this, but I did not pursue it.
I must admit I spend more time of Angry Birds than actual bird behaviour! Cindy, my nemesis, is a whiz, as is my daughter, Caitlin!