I live in a fairly cold part of the country, so it amazes me to see so many resident birds in the winter. It’s often easier to observe their daily habits during this time of year because there is less leaf cover to obscure their activities. Observing their behavior got me thinking about how do they actually survive and why do some choose to stay while others travel so far away.
Of course, this led me to seek out a fantastic book on the subject. Birds In Winter: Surviving the Most Challenging Season by Roger F. Pasquier, was published in 2019 by Princeton University Press.
Although I am only through the first 100 or so pages, I thought I’d share some of the fun facts I’ve learned thus far about birds and their winter survival tactics.
I already knew some concepts like they eat more to add a fat layer and they can fluff and arrange their feathers for optimal warmth. Those birds that are less efficient as maintaining warmth or need foods that are not present during winter migrate to a better location. But there is so much more!
Here are some fun facts:
- Most existing bird species have lived through at least one glacial period. Many have been through several. They’ve encountered winter on the grandest of scales.
- Not all birds migrate to escape winter weather conditions. Some tropical birds also migrate because of changes in local rainfall that affect their food supply.
- There are several different types of migration. One type known as altitudinal migration happens when species move down (or up) the slope (elevation) of a mountain to follow its food supply.
- Birds that do not migrate or have a shorter migration benefit from greater reproductive potential because they spend less time traveling. This assumes that they survive the winter, which isn’t always a given.
- Many species store food for the winter. Some use a technique known as scatter-hoarding (i.e. food in many locations). Others do larder-hoarding (i.e. food all in one cache). Red-bellied woodpeckers (Melanerpes carolinus), for example, do the former while red-headed woodpeckers (M. erythrocephalus) do the latter.
- Many birds hide their food in trees. (I’m not sure why this never occurred to me.) Some secure them in the lichen, others drill into the bark, still others use the bud capsules at the tip of the branches. There are many different storage strategies.
- When a species migrates to a wintering site, it is often entering an area where other migrants, as well as resident species, reside. To avoid most food-sourcing conflicts, the arriving species may choose a marginal habitat that is productive only seasonally or may produce food that is inadequate or unsuitable for other species.
These represent only a fraction of the topics covered in this book. It is full of specific details about species and compiles scientific studies in a way that makes them accessible.
I encourage you to see if your local library carries a copy of this volume so you can check it out for yourself. Then, turn your eyes to the outside with a greater awareness of the winter chores those birds are undertaking.