Molt in North American Birds (Peterson Reference Guide)

Do you break out in a cold sweat whenever someone utters the word “molt”? Instead of Freddy and Jason, do Humphrey and Parkes haunt your dreams? If so, then you no longer need to fear fallen feathers, for Molt in North American Birds is here.

Most birders, and even many nonbirders, are familiar with the concept of molt. Simply put, it is “the systematic process of feather growth ”. This process is of great significance to both birds and those who watch them. Molt is critical to birds, as feathers would become too worn to support flight and thermoregulation if not replaced regularly. For birders, understanding and recognizing molt can aid in identification and bring insight into birds’ lives.

But the concepts and terms associated with molt can be very confusing. I’ve read about it multiple times, but I still get confused about what complex alternate strategy means. That is, until I read Molt in North American Birds. Howell has a way of making this subject surprisingly interesting and, if not simple, at least understandable.

Unless you already have a strong understanding of molt and its terminology, then start with the 66 page introduction. Let me say that again: read the introduction first, preferably in its entirety, before proceeding to the rest of the book. Unlike most bird books consisting primarily of family accounts, you’ll have a hard time comprehending the accounts if you aren’t familiar with the basics.

Through clear text and helpful photographs and figures, the introduction describes what molt is, the fundamental molt strategies, how it impacts birds, how birders can recognize it, and much more. Frankly, I was a little surprised at how extensive the introduction was. Granted, a good portion of the real estate is occupied by illustrations, but there is so much more information here than one would expect for a “limited” subject like molt. One such subtopic, wing molt strategy, is given extensive coverage, which is very welcome since it’s one of the easiest artifacts of molt to detect.

The family accounts “review the molting strategies of North American bird families and relate them to different aspects of their life history and ancestry, showing how molt offers new insights into the fascinating world of birds”. Each one starts with a general description of the family and their molt, and then proceeds to more specific details on their preformative, prebasic, and/or prealternate molts. They conclude with a list of references.

The accounts range from one to eight and a half pages, with an average of two or three. Some of the shorter ones, like Creepers and Kinglets, take up a full page only because of extra-large photographs.

Honestly, I was expecting the family accounts to be great references to turn to if you have a specific question on the subject, but otherwise relatively dull and monotonous. Well, they are, indeed, a superb reference, but I was wrong about the rest. I was delighted to find that they were all worth reading through. Howell’s writing is clear and easy to understand, but even better is the way he keeps it interesting. He goes into details, raises questions, and offers insight into birds’ lives. For instance, he doesn’t simply report that most Empidonax flycatchers complete their prebasic molt on their wintering grounds. Nor does he mention that Hammond’s Flycatcher is an exception to this and leave it at that. He asks why Hammond’s would have such a drastically different schedule than Dusky Flycatchers, even though they often breed and winter in the same mountains. Howell posits that it could be related to variations in the food supply within their specific habitats. Hammond’s breed in higher forests that offer more food later in the year, enough to fuel their molt. Dusky Flycatchers, on the other hand, breed in drier and scrubbier places that may not offer as much food as their wintering grounds, and thus wait to molt.

It’s like this throughout the book; you never know what fascinating tidbits you may uncover. Here are just a few more examples. Bullock’s x Baltimore Oriole hybrids may attempt to molt twice in a season, the stress of which could hinder their survival. Ever wonder why adult male and young Red Crossbills vary so much in coloration? It’s likely due to when they molt. Finally, the Black-capped Petrel might actually comprise two separate species. Observed differences in molt timing indicate disjunct breeding schedules, which would make these populations effectively isolated even though they breed in the same location.

The many photographs, most by Howell himself, are large and of very high quality. There is nary a page without at least one photo, making this a very attractive, in addition to informative, book. But the photos are there for more than just looks, they are often instructive in and of themselves, especially in the introduction. They have been carefully chosen to illustrate the various concepts and show what molt actually looks like. I’m also happy to note that all captions include the location and date the picture was taken.

The only problem I found was a weird yellow box in the corner of two photos (the Golden Eagle on page 122 and Pauraque on page 173). I’m not sure exactly what they are for, but my guess is that it is an overlooked leftover from the layout/printing process.

Recommendation

As Howell writes, “paying attention to molt can also help you get more out of your birding” – it can provide insight into behavior, add value to your field notes, and even aid in identification. And now birders have the definitive guide to this process in Molt in North American Birds. I wouldn’t recommend it to beginning or casual birders, but for those serious about the study of birds, it will be indispensable.