As scientists, we work hard to study questions that interest us, and to gain an understanding of the natural world. It is a deep fascination with the world that leads us all to pursue scientific knowledge. What our group wanted to gain knowledge of was the American Crow, and in our pursuit of that knowledge, we have learned much.
Joe McKenna/Flickr Creative Commons
Crows are some of the most common birds found in areas largely affected by anthropogenic influence. They are opportunistic feeders, which is one of the main reasons they have been so successful in urban and suburban settings where disposed food and other small animals are plentiful and available. Suburban settings are comprised of varying levels of human development including neighborhoods, small businesses, and parks, each of which provide foragers with different food options. Crows are extremely intelligent and can recognize regular sources of food and return to those areas for future feeding options. Though crow abundance increases in developed areas, studies have also shown decreased size and overall health of crows that feed primarily on processed food. For this study, we wished to better understand how crows exposed to a variety of food sources choose from the plethora of available options, and if these selections have anything to do with the location of foraging.
Image credit: Urban crows eating garbage / Crafty Green Poet
We performed our experiment in Bellingham, a medium-sized city along the northwest coast of Washington state. We chose three distinct suburban locations, including alleyways near the local university, forested parks, and parks located along the coast of Bellingham Bay, and offered them food options commonly found each location, including processed turkey meat, a feeder mouse, and a mussel, respectively.
This quarter we have learned through hands-on experience that data collection can be at times difficult, uncomfortable, and unproductive. Finding the time in four people’s busy schedules can be essentially impossible. You also have to schedule around the time when your target animal is going to be detectable, making it even more difficult to collect a large enough set of data. Luckily, crows are not very difficult to find. They are deep black and medium sized, making them stand out in most locations. They are also very loud, and do not seem afraid of humans. Finding crows was not very challenging, gathering data for our experiment was much harder. In fact, half of all of our observational periods were unsuccessful in yielding any data. We did a total of 18 trials in our six locations, and only collected results for nine of them. Considering that each trial look us 20 minutes, that’s a total of 4.5 hours of unsuccessfully trying to get crows to go for our bait. We found that playing Crow calls, as in this video helped attract more Crows:
Though we had some difficulties, learning about crows this quarter was absolutely fascinating and entertaining! Crows that did not go for our bait were replaced by seagulls, park cleaners, and small children. There was one instance where Patrick had to frantically yell at a group of toddlers huddled around our dead mouse. One of the toddlers had almost picked the mouse up and was barely stopped. The presence of dogs were also a constant and worrying threat to both our experiment and the dog’s health. Luckily, none of our bait was eaten by dogs. We also observed some sort of hierarchy among certain birds. While Marissa and Maia were in the alley behind High St., two crows approached the selections of bait. There was a small fight or tussle, and the one of the crows flew down to make its selection first. It sniffed the turkey meat, and then moved on to the mouse, picked it up and flew away. Then the second crow was then able to approach the remaining food options. This crow also sniffed the turkey meat, moved on, and selected the mussel.
Image credit: Dave W / flickr
Throughout these last ten weeks, we have overcome small children, the smell of decaying mussels, and bloody mice, but thankfully, we did learn something. We found a slight preference towards the feeder mouse in all three locations, but statistical tests did not reveal a significant correlation between food selection and location. This goes completely against our hypothesis but does hint at some sort of correlation. As most proper scientific experiments do, this raised more questions for the team. Why was the mouse picked? Simply because it is more visible? More nutritious? Preferred in Bellingham? Do crows and seagulls prefer different foods? Though inconclusive, continuing research on feeding preferences of animals that thrive in anthropogenically altered spaces could be highly informative to future crow management, as well as the greater concept of human coexistence with the natural world.
This is a Youtube video made by BBC demonstrating some of the amazing things about crows. Their ability to recognize faces and use tools is so mind-boggling! Crows make you question whether calling someone a “birdbrain” is really an insult:
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