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Special to the Mirror
As snow slowly falls in the region, not many birds in the area are out fluttering around. Many flew south before the first snowfall of the year to begin migrating.
But others, like the chickadee, stay hunkered down in Pennsylvania and surrounding states. There may not be a lot of food to find for these small birds, but the chickadee doesn't need to go hunting for food in the cold winter months. Instead, it relies on caching.
It's a way of survival for the chickadee.
"We think of food caching as this alternative strategy to migrating, so instead of moving towards where your food will be, you can keep the food where it is or the food where you are, and use that throughout the winter," Carrie Branch, a Rose Postdoctoral fellow at the Cornell Lab of Ornithology said.
Branch took part of the Cornell Lab of Ornithology's webinar in January regarding how chickadees use their brains to hide seeds and survive in harsh winters. She was one of two experts on the panel along with Ben Sonnenberg, a graduate student at the University of Nevada, Reno.
"Chickadees are just a fantastic group of birds that are easy to study, and convenient to study," Sonnenberg said.
Chickadees are birds that are common throughout the United States and all of North America. In addition, these small birds can be found throughout Europe and Asia. The only areas they aren't found is Australia, South America and Antarctica.
One focus Sonnenberg and others looked at was chickadees in low elevation compared to those in higher elevation, and how they differ with caching.
"We've been studying these birds for a really long time and there's two elevation sites, one's a high elevation (8,300 feet) and low elevation (6,700 feet). We found lots of elevation-related differences and variation in laboratory setting," Sonnenberg said. "It started in the lab. We found differences in caching behavior, we found differences in spatial memory. There's differences even in neural anatomy in birds."
What the team found was that birds in the higher elevations had higher caching behavior, higher spatial memory and higher neural anatomy.
Spatial memory is studied in the birds through cognitive tests.
One example of those tests is the use of feeders and seeing if birds remember which one will give it food.
"Cognition is this really broad topic and cognitive physiology is one of the main interests in this lab that we've been a part of," Branch said, noting such tests as spatial tests for rats, or counting tests for monkeys and fish.
"When we start thinking about things like natural selection acting on cognitive abilities, we often think if there's variations in a trait, it must be useful," Branch said. "In reality, we shouldn't expect organisms or animals to be highly cognitive unless it's really critical for their survival or reproduction.
"Being highly cognitive isn't always a better trait to have," Branch added. "I always say that animals are as smart as they need to be, and I stole that quote from somebody else so I don't want to take credit for it, but it's true."
An example Sonnenberg noted was if a chickadee comes to a feeder with multple feeding windows and notices one window doesn't give food, it will go to the next and try that one, and repeat until it finds one that does give it food. And interestingly enough, once a chickadee does find which feeder opening gives it food, it doesn't make a mistake again when going to the feeder for more.
Animals use spatial cognition to navigate throughout their environment, be it for food sources, territorial reasons or finding a mate. An example as well is seasonal migration.
"(Seasonal migration) is one of those things that is innate and organisms have an innate response to migrate during certain seasons based on cues they're getting from the environment," Branch said.
But for the chickadee, there is no migrating to warmer climates in the southern United States. They simply find sources of food and cache it where they know where it's at. Which can become an interesting phenomena, as some birds and animals cache differently.
For instance, scrub jays, nuthatches and even grey squirrels scatter hoard and hide their food all over their territory.
Nutcrackers, pinyon jays are in-between species who store a couple of seeds in just one location.
And then there's larder hoarding, such as the acorn woodpecker or red squirrels, who store a lot in just one location and defend their area.
"There's actually a scalar gradient of hoarding behavior," Branch said. "We refer to this as scatter hoarding vs. larder hoarding."
Branch noted that for a long time, people were studying the differences between caching species and non-caching species.
"Black caps are great for that (studying in winter harsher environments). So while it wasn't focused primarily in the northeast, that study looked at variation, and it's not about just the latitude," Branch said. "Just because there's an increase in latitude doesn't mean the birds are performing better in spatial tasks. Birds in Washington have terrible spatial memory, but they're living life of luxury up there because it's sort of a Mediterranean climate."
Sonnenberg noted that they are able to study chickadees thanks to them frequenting nest boxes and not leaving.
"They don't migrate, so we can monitor specific individuals all year long. We can take DNA samples. In the winter time, we collect cognitive data," Sonnenberg said. "In spring and summer, we collect all sorts of reproductive data. How many eggs do they lay, how many babies do they actually fledge, how many parasites are in their nests, who's mating with whom?"
While the winter around central Pennsylvania this year has been fairly cold recently with a good amount of snow, chickadees in the area are able to survive with the caches they were able to store throughout the fall months.
"There's a strong innate drive to go cache. Caching ability develops pretty early, but associated ability to recover those caches develops a little bit later. Birds cache heavily when resources are available," Sonnenberg said. "Early fall to late fall and even in winter months (they cache), but amazing thing about chickadees is if you give them food to cache, they'll cache it."
Sonnenberg noted that's not unfamiliar at all in black cap chickadees, from Maine to all over the East Coast and out west.
"Sometimes you see a bird grab a seed, then fly off to branch and eat it, but sometimes you'll see them disappear, and sometimes they cache that seed," Sonnenberg said. "If there's food to cache, they'll cache it. It's a very interesting component."
And one that's critical to survival.