![]() ![]() 4 One thing that’s for certain is that migration is a daytime affair. 3 The longest migration on record is 1740 miles. In a study that looked at crows from both sides of the country, the average distance traveled by east coast crows was 287 miles, while west coast crows traveled an average of 366 miles. 3 As a result, migrating crows show extremely high site fidelity returning to the same breeding and winter sites each year.Īs far as distances go, there’s huge variability there as well. ![]() But in the studies conducted so far there’s been no evidence that crows pick and choose each year, rather it seems that you’re either a migratory individual or not, albeit this is based on low sample sizes. From a climate change perspective, that individual birds might be able to choose whether or not to migrate each year would have important implications in their ability to adjust to changing conditions. Likewise, whether migrating is a discretional activity is still in question. 2 What motivates these shorter-distance trips remains to be seen. But studies have shown that other crows make even shorter migrations, only about 350 miles between contiguous US states with similar climates. For instance, birds living in the Central and Southern Canadian provinces will nearly always migrate hundreds of miles south into the US, which makes sense because Canadian winters can be especially harsh. In some cases the answers to these questions are surprisingly nuanced. Why do some crows migrate and others do not? Do the same crows migrate each year or can they opt out? Do they return to the same place? How far do they fly? How do they survive the journey? How do they sleep? ![]() Because there are so many questions one could ask about this phenomenon. But given the value of better understanding this behavior, as well as the technological advances that make it possible, western science has finally turned its eye to inspecting these patterns more closely. Some did it, some didn’t, and that was that. Until the last decade or so that’s really all we knew about about crow migration. So much like a wealthy aging relative, they snowbird it to more welcoming climates for the winter. Because while crows in temperate Seattle may be quite comfortable year round, those that call higher latitudes “home”, say central Canada, would have a tougher time making it through the winter unscathed. Partial migration is when only certain individuals within a population migrate, while others are sedentary, and it’s this one that applies to crows. 1 But there are other types of migration including short distance migration, altitudinal migration (short migrations from shorter to higher altitudes) and partial migration. Of the world’s ~ten thousand birds species, only 18% actually undertake annual long distance migrations. But at the intersection of these truths is an interesting question: if migration seems such an essential part of bird life, why don’t crows do it? Or do they? Their predictability on our telephone poles and near our garbage cans is one of those quiet details not everyones thinks of often, but whose consistency surely calms us as so many other things feel unsteady. Or, if you don’t want to get that deep with it, there’s always Looney Tunes or any number of other children’s cartoons to remind us that some birds come and go with the seasons.Īt the same time, for most of us living in the continental United States, that crows will be nearby to accompany us throughout our year is something we take for granted. Their ephemeral presence offers an opportunity to ground ourselves in time and place and reflect on the shape of our lives since our last meeting. Whether it’s the arrival of technicolor spring migrants, or the din of waterfowl above our heads in the fall, it takes no formal training to recognize that something novel and beautiful has suddenly erupted into our lives. That birds travel seasonally is perhaps one of the most familiar facts about the natural world. ![]()
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