November 17, 2015
Thank you to Max Witynski, student blogger, for writing this great post about caching behavior in our feeder visitors!
Have you ever wondered why some birds visit your feeder again and again and again throughout the day, taking sunflower seeds “like there’s no tomorrow?” It’s not just because they’re hungry—these birds are actually planning for tomorrow.
In late fall, chickadees, titmice, and nuthatches increase the rate at which they visit bird feeders, but they don’t eat the extra seeds they take right away. Instead, they hide the food in bark crevices, needle clusters, knotted branches, and other nooks and crannies near feeders. Birds will even store seeds in man-made structures—I once saw a white-breasted nuthatch hanging upside down from a gutter, tucking seeds beneath the siding of my house!
This behavior is called caching. By storing seeds, the birds ensure they will have something to eat later when food is scarce.
Caching has long been of interest to ornithologists and animal behaviorists, and their research has taught us some amazing things about the behavior and the birds that perform it.
In a 1984 paper in Animal Behavior, David Sherry reported the results of lab experiments which demonstrated that black-capped chickadees can not only remember where they have stored seeds, but also which caches they have already eaten, which caches they have discovered eaten by other animals, and which caches contain their favorite food items. Sherry also found that chickadees can remember the locations of their caches for 28 days after they have created them.
These adaptations for efficient food storage and recovery take a lot of brain power. Chickadees have relatively large hippocampi (a part of the brain important for spatial memory) compared with other birds, and they even grow extra neurons (brain cells) in the fall when they are busiest creating and remembering new caches.
Chickadee caching is impressive, but Clark’s nutcrackers—relatives of jays and crows found in the mountains of western North America—take caching to a whole new level. These birds can establish thousands of caches containing a total of 100,000 seeds in a single year.
Nutcrackers are also important seed dispersers for a number of tree species. When a nutcracker forgets to return and eat a cache, the seed may germinate into a young tree. Whitebark pines in particular are reliant on nutcrackers to move their seeds around the landscape. Taza Schaming, a PhD student at the Cornell Lab of Ornithology, studies the relationship between the nutcrackers and pines in Wyoming and the conservation implications of their mutualism in light of an introduced disease which is killing whitebark pines in the West. Her work was the subject of a recent article in LivingBird Magazine.
So next time you see a chickadee fly away from your feeder with a sunflower seed, watch closely and see if he hides it nearby—don’t let him see you though: chickadees are less likely to cache seeds when they know potential thieves are watching!
Foote, Jennifer R., Daniel J. Mennill, Laurene M. Ratcliffe and Susan M. Smith. 2010. Black-capped Chickadee (Poecile atricapillus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online:
Sherry, D.F. 1984. Food storage by black-capped chickadees: memory for the location and contents of caches. Animal Behavior 32:451-464.
Sherry, D.F. & Hoshooley, J.S. 2007. The neurobiology of spatial ability. In: Otter, K. (ed.) Ecology and Behavior of Chickadees and Tits: An Integrated Approach (pp.9-23). Oxford University Press: Oxford.
Link to article about Taza Schaming: click here.