Tuesday, August 03, 2010

Summer is "flying" by

Here it is the beginning of August. School starts back up in just a couple of weeks!
After completing the owl surveys earlier in the summer, Karyn and I took a much needed vacation to the Stanley Idaho area. There we hiked, mountain biked, and admired wildlife. Upon our return I started working up at Lucky Peak banding songbirds for the Idaho Bird Observatory. I call it work, it is really volunteering. Karyn refers to it as my summer camp! This activity continues their 15 year work in studying avian migration. It was the basis for my undergraduate research into the weather effects on avian migration and supports many other important studies as well. This is the second summer I have worked there. Its hard to believe that its already week three in my four week assignment there. After that I return to school for a week of teaching assistantship orientation and then the fall semester begins! Wow, where did the summer go?
Banding songbirds is a great way to learn a lot about birds. Not only does it help with identification, but also the birds life history and ecological requirements. Songbird banding at Idaho Bird Observatory begins in mid-July and continues through mid October. Hawk banding begin in late August and continues through the end of October. The songbird nets operate for the first 5 hours after sunrise every day. We currently have 4-6 people working each morning.
The focus of the banding activities is on avian migration. Early in the season we mostly catch local birds which are dispersing through the area, but there are a few migrants coming through. To catch these few migrants we must start as early as mid-July. The Lucky Peak banding site is considered a stopover site. Migratory birds stop there to refuel before continuing their long journey south. Just before migration begins, they experience a hormone change which causes them to enter hyper-phagy (eating a lot). Their body also shifts to load up on fat to fuel their journey. We can tell that a bird is migrating or getting ready to migrate by examining its fat stores, one of the many attributes we measure on each bird banded. The first "loaded" bird I banded this year was a beautiful male Bullock's Oriole heading south. We only delayed his journey for a few minutes...
Bullock's Oriole heading south!
Many people talk about how hard it is to identify birds in the wild. This is illustrated very well when it becomes difficult to identify birds in your hand! Some of the most confusing that we handle are the flycatchers. The difference between a Dusky Flycatcher and a Hammond's Flycatcher is very subtle. Sure, there is the primary projection rule, but what if the bird is a juvenile that is still growing its tail feathers? Bill size? There are differences, but they too are subtle. Then its gets down into the details ... such as primary feather #10 in a Dusky is longer than feather #5, about the same in a Hammond's. Now memorize these rules for the 100+ species we catch at Lucky Peak and there is always lots to learn. A while back the "Western" Flycatcher was split into the Pacific Slope Flycatcher and the Cordilleran Flycatcher. We do catch a number of westerns, but which species is a quandary. The reference guides say we only have Cordillerans here in Idaho, but all that we catch measure up to be Pacific Slope. Hmm. For now we just call them Westerns...
Hammond's Flycatcher (l) and Western Flycatcher (r).
Some species just make it easy. There are no mistakes with the male Lazuli Bunting. I love these birds.
Male Lazuli Bunting.
Once past the identification of species, we measure wing chord (length), tail length, fat score, muscle score, feather molt and wear, try to identify the sex, and the age. Sex is easy in some birds and just not possible in other species. Age is also a very tricky determination. Its usually easier to tell hatch year from after hatch year, but determining second year from after second year can be a challenge. In most species the birds don't molt all of their feathers during the second year, but in the third year they will replace all flight feathers within a very short period. Thus, to age the bird we try to analyze the flight feathers to determine if they are of different ages. If they are of different ages, then the bird is likely a second year, if the feathers are all the same age, the bird is likely an after second year (can't age beyond this). Making this more difficult is that different species will have different approaches to feather replacement. Lazuli Buntings are unique in that they replace their outermost primaries and innermost secondaries, but not the ones in the middle during their second year. This is illustrated in the photo below (it is rarely this obvious!).
Molt limit in male Lazuli Bunting.
You can see the outermost 6 feathers are darker (newer) than the next 5 feathers, then the next inner feathers are also newer. The primary coverts (small, short feathers "covering" the outermost flight feathers) are also old. These wear slowly so it makes sense to use them as long as possible. Growing new feathers is a very expensive process.
We often catch juvenile birds which might still be fed by their parents. Under these circumstances, we quickly process and return the birds to where they were caught. We often get to watch as the parent immediately feeds them. Its pretty cool. If we catch birds of the same species together, then we process them and then release them together. Yesterday, I extracted 4 juvenile Black-capped Chickadees from the net. We processed them and then delivered them back to the area where they were caught to regroup with any others they might be marauding with.
Juvenile Black-capped Chickadees.
The Idaho Bird Observatory is located east of Boise Idaho on top of Lucky Peak. We welcome visitors. Come by and check us out.

3 comments:

Idaho Birder said...

I hope to get up the IBO with my family this Saturday morning.

It sure was fun to run into you and Karyn on the trail to Knapp Lakes.

Best wishes for your studies and teaching this year.

wolf21m said...

Robert, have fun up there. I am actually off for three days so I will miss you. It has been slow the last few days, but some interesting birds none the less. I also expect it to start picking up soon.

marydrakeface said...

I was searching for photo-reference to draw some black-capped chicadees and came across your picture of the four in your hands. When I was little my grandpa used to teach me all about bird identification via books and observation at home in Western Massachusetts. I enjoyed your post about how in-depth bird identification is and learning about some of the hands-on ways to gather information. I wish I had retained all the things I knew about bird from when I was a little kid, because they really do still fascinate me.