Interspecies Cooperation and Communication: Black-capped Chickadee and Tufted Titmouse

 In theory, every species expends its energy to further the continuation of its own genetic code. One might assume that means not aiding other species of dissimilar genetic code, especially those that compete for the same resources in a common environment. Essentially, however, it is in the interest of every species to maximize its return on investment in terms of genetics. So, if helping a species that competes for the same resources results in a higher overall survival rate of one's own species, then helping that other species survive is an overall net win. It's basic game theory.

For the strategy to be effective, the effect of the lost resources taken by the other species has to be outweighed by the benefit gained from having the other species sharing those resources.

Let's look closer at two example species: the tufted titmouse and the black-capped chickadee. In New England, and specifically where I live in New Hampshire, the Tufted Titmouse and the black-capped chickadee share the same territory. Where you find one of these two species, you are quite likely to find the other. They will even visit bird feeders together. They generally eat the same foods and should be protective of food resources against one another, but they are not. So, it seems, the benefit to each species of having the other around must outweigh negative effects of sharing available food resources.

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What sort of aid might they give each other? One type of cooperation is that they both give vocal warnings when they notice a potential threat and each species responds to the threat call of the other. This gives the advantage of extra sets of eyes watching out for danger when the birds are feeding. In this video you can here the alarm calls of both the chickadee (the familiar CHICK-A-DEE-DEE=DEE call) and of the tufted titmouse whose call seems to me tonally similar to the DEE-DEE-DEE part of the chickadee alarm call. At twenty-two seconds into the video, you'll hear the tufted titmouse's alarm call. At forty seconds, the alarm call of the black-capped chickadee.  Both bird alarm calls are meant to be loud and attention getting, so that birds in the nearby area can hear them and be alerted to the threat. Chickadees even change their call to indicate the severity of the threat and whether the threat is from below or from the sky. In that sense, it's a primitive language in that they are communicating specific meanings with their vocalizations.

In the case of these two bird species, it seems, the benefit of having that extra warning when there is possible danger outweighs the burden of sharing food and habitat with each other. 

What are some other forms of interspecies cooperation that you've noticed? Let us know in the comments below.