Understanding the bird’s wing!
Birds use the ability to fly for finding food, escaping from predators and even migrating to areas that can better support them when there are fewer resources available. Obviously their feathers are not permanent to their body and they need to replace their older (worn) feathers with new (sturdy) feathers. The molting (loosing and growing new feathers) patterns on the wing of the bird can help us banders understand the age of the bird (well sometimes).
The biggest problem with looking at the wing to identify their age is that most species have a different wing molt pattern! Majority of the passerines will replace some but not all of their juvenal wing feathers when going into their 1st prebasic molt (molting into their adult plumage their first summer before migration). The following summer the passerine will then do a complete molt replacing all of their wing feathers and then officially becoming an adult. Some species like the blackbirds and Cardinals will go thorough a complete molt when coming out of their juvenal plumage and then unable to age them (well, unless they accidentally retain one juv feather by mistake). Confused?? Bird banders can also be confused with the molt limit location! That’s why we use the Identification Guide to North American Birds Part 1 that tell us about where to look for the molt limit in each of the birds. There is a new molt photographic guide that should be coming out soon and will be even more helpful with aging birds for us that need an arrow pointing to the exact location of the molt limit in each hatch year birds.
“Many” non-passerines or “near-passerines” will regularly retain their flight feathers when going through their molt. If the bird looses too many flight feathers (like the Canada Goose) they will not be able to fly and then unable to find food! Lucky most ducks/geese are in the water with their goslings and don’t need to fly at that point (finds food on the ground/water) so molting all their feathers isn’t a problem. There are many other reasons for some species not to be going through a complete molt and has to do with amount of energy required to molt new feathers! Of course the energy problem is truer with our larger birds (who have larger feathers) than with smaller birds like hummingbirds.
Currently many of the wings that I have been looking at the past few months are the Northern Saw-whet Owls wing. Lucky some fellow banders have discovered that by using a black-light on the Saw-whet’s wing (currently the only species I know that this method works with) will result in showing newly grown feathers glow pink in color. Looking at the below picture . . . . you will notice that the whole wing is pink making this fluff ball a hatch year bird. If it had been an adult owl . . . . the wing pattern would show the older feathers whiteish in color. Even with the numerous recaptured Saw-whet that us banders have recaptured, we are still struggling with understanding the age of birds older than third years of age.
Hope I didn’t confuse everyone but I am off from work this week and stuck with snowy weather (unable to band owls). I am just in the blog babbling mood (well in-between watching The Price-is-Right, etc..) !
|Subscribe to Mon@rch||All Rights Reserved ©2006-2007|