New citizen science project to add to your schedule

This past February, the Hawk Migration Association of North America (HMANA) initiated the Winter Raptor Survey, a volunteer effort to determine winter abundances of raptors. The purpose according to the association’s website “is to get birders/raptor enthusiasts out in the field during the winter looking for diurnal raptors, and to provide those surveyors with a set of guidelines enabling them to record their observations in a standardized format.”

While 2007 was the kickoff year, birders are still being encouraged to make their own 30-100 mile route and record raptor species seen from this car route between November and March. Instructions and data forms are available on the HMANA website.

This is a great opportunity to get out for a nice drive and possibly see some of the rarer winter raptors such as Rough-legged Hawks as well as some of the other common species.

Monitoring in this way is a great conservation tool and the results will be published in the associations publication, Hawk Migration Studies.


Banding the Saw-whets

female Northern Saw-whet Owl

A few nights ago I had the opportunity to help band saw-whet owls at a Girl Scout camp close to Halifax, PA. This excited me because, although saw-whet owls are one of the commonest owls in Canada and the northern US, I have rarely seen them. These owls are tiny, with the males only weighing as much as an American Robin (~75 g) and females just a little more than that. Saw-whet owls are a common target for banding because they are migratory, arriving in PA between October and November.
We were looking forward to a busy night because a cold front had just passed thru and the wind was generally calm. Plus, we had heard reports from further north reporting some huge catches recently and were expecting a huge influx at any time.

a little male

Our first net check produced 2 owls, the very small male in the photo above, and the female that is squinting at you in the first photo. You can also see the leg sizing tool and banding pliers in the above picture.

qualifying eye color

There are a lot of unknowns as far as ageing saw-whet owls. To better determine different characteristics that might give clues to age, many banders take additional information such as eye color, amount of white in face and amount of barring on the alula. Above, the bander is comparing the shade of the owl’s eye to a paint strip.

wing from the squinting female above

By looking at the condition of the wing feathers, it is sometimes possible to tell how old the bird is. Without getting too technical, you can see that the outer five primaries (p6-p10) are darker than the inner five primaries (p1-p5) and the adjacent 5 secondaries (s1-s5). The inner secondaries are again darker like the outer primaries. The darker feathers are from one molt cycle and the light feathers are from the previous molt cycle. This would make the owl at least 2 years old.

underwing shot with blacklight

Another way to look at feather age is to shine a blacklight on the underside of the owl’s wing. The newer feathers have a pinkish wash to them that really stands out when under a blacklight.

something on the ceiling

Occasionally the owls would become fixated on something in the room as they were being banded. sometimes it would be a face but other times it was hard to say what exactly the owl was looking at. This was one of those cases.

perched on the tree

After spending time being banded under lights, the owls are set out on a specific tree to recover their night vision and preen their feathers back into alignment. Occasionally they will remain for quite some time. The above bird remained for about half an hour as we closed the nets due to rain. We came back and were able to take pictures using a red light and no flash. We didn’t end up with the large catch we were hoping for but the 3 owls we did get provided the banders with valuable information and me with cute pictures and something to blog about.

Northern Saw-whet Owls are breeders in the forests of s. Canada of n. United States that are being logged at an accelerating rate. Regenerating forests do not provide the dead snags that are necessary for nesting. Already hard to observe, a declining population could mean that they will become downright impossible to see. Saw-whets do use nest boxes so if you live in a region that supports nesting Saw-whets, consider putting up a nest box.

For more info on the banders work visit Scott Weidensaul’s research page. You can also support thier work by adopting an owl.

The Moth Invasion of `07

Gypsy Moth Lymantria dispar

It’s particularly bad this year. At least I don’t remember noticing the large swathes of mountainside that were nearly absent of any green. While the gypsy moth caterpillar can be a real boon to birds such as cuckoos which feast on the insects, they can also cause tremendous damage to their hosts which include oaks and aspen.

According to Donald Eggen, director of the Office of Forest Pest Management for the Pennsylvania Bureau of Forestry, “Nearly 700,000 acres of Pennsylvania forests- primarily in the Poconos and central Pennsylvania- were defoliated last year because of the persistent bugs, and the infestation could be worse in 2007.”

Originally introduced accidentally around Boston in 1869, the first outbreaks began around 10 years later and it 1890 the first attempts were made to eradicate the moths. Unfortunately they were not successful and the moths still are causing problems over 100 years later. Below is the projected spread of the moths if their range continues expanding at the present rate of 21 km/year.

The effects of the gypsy moths could very well mean that only the less susceptible tree species will dominate the forest and some ecologically and economically important trees such as oaks will be lost.

Over the last 100 years over 20 insect parasitoids and predators from Europe and Asia were introduced to help control the moths with limited success. Birds feed on the insects but apparently not in quantities that affect the moths populations. More recently a virus and as well as a fungus have had good success in limiting the outbreaks. Unfortunately this year spring came so late that the fungus did not have time to have its effect before the caterpillars hatched and that is why there is a larger outbreak this year.

Moth outbreaks are currently also being controlled by direct spraying in areas that are hit under a joint program of state governments and the USDA Forest Service. If you are witnessing an outbreak on your property you should contact your extension service for more information on programs in your area.


WBOC-TV- Gypsy Moths Leaving Their Marks on Mid-Atlantic Forests
USDA Forest Service- Gypsy Moth in North America

Eastern population of Golden Eagles being tracked

The National Aviary in Pittsburgh and Powdermill Avian Research Center are both working on satellite tracking several Golden Eagles that were trapped this fall near the Allegheny Front Hawk Watch near Bedford, PA. I was lucky enough to be in the trapping blind for a day when 39 Golden Eagles and 1 Bald Eagle migrated past but unfortunately we only caught two Red-tailed Hawks. The eastern Golden Eagle has been recognized as a geographically and genetically isolated population for more than two decades now and it is crucial that we understand how their migratory behavior might be affected by proposed wind power projects along the Appalachian ridges. According to one article…

The possible increase of wind power on Appalachian ridges may threaten golden eagles as they travel their historic migratory corridor that follows these mountains through Pennsylvania to reach their nesting grounds in eastern Canada or wintering grounds in the southern reaches of the mountain chain. Since all known eastern golden eagle migratory routes track over the Appalachian Mountains, possibly along or in close proximity to ridges targeted for wind power development, the Game Commission must ensure the well-being of this state and federally-protected species – as well as other wildlife – as this growing industry sites turbines between the state’s Allegheny Front and Blue or Kittatinny Ridge. -according to

Below are the tracks of two Golden Eagles that were trapped this fall.

For more info on this project, click here.

Study reveals further declines for the world’s waterbirds

Solitary Sandpiper (Tringa solitaria)
In the somber news category, the fourth edition of the Wetlands International report on waterbird species around the world has been released. It’s based on annual field surveys by 15,000 voluntary expert observers across hundreds of sites worldwide, including many IBA’s. Of the 878 species that they present estimates and trends for, 44% are either decreasing or have become extinct since the last edition was released 4 years ago.

Read the full article.

Solitary Sandpiper © 2006 Drew Weber

How to count birds

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Snow Geese flock, originally uploaded by topherous.

Cornell Lab of Ornithology’s eBird site has just posted Bird Counting 101. For anyone who spends time out in the field watching large flocks, whether they are shorebirds, waterfowl or hawks knows that estimating flock size can be ridiculously hard. Just looking at the flock of Snow Geese above is overwhelming if you want to try and estimate the number of birds. Estimating sizes of flocks can be biologically important because it is an additional data set that can be more useful than just knowing whether a species is present or absent.

Cornell puts forth several different tips for counting in their first installment:

  1. It is very important to write your observations down right away. No one can remember counts for 40+ species at a time. You will also end up second guessing yourself if you don’t write down what you see, particularly with the more common species, “Did I really see a Mourning Dove today or was that yesterdays walk?”
  2. Be conservative in your estimates, making sure you are not counting birds twice.
  3. For larger flocks, count a small portion of the flock and then extrapolate for the rest of the flock. For instance, count 10 birds in the flock and get a good idea of what that feels like. Then count the flock in 10 bird increments. This fall I was the counter on South Lookout at Hawk Mountain Sanctuary, PA on the morning that a flight of over 5,000 Broad-winged Hawks migrated through. I mainly counted in 5 and 10 bird increments because the birds kept coming and coming and coming.

One fascinating fact from the article was that we have a hard time estimating flocks when they are flying in 3D space. If a large blackbird flock is 100 birds wide, 100 birds long, and 100 birds deep, that is 1,000,000 blackbirds! I have a hard time imagining that.

Check out the full article.

Vulture chick brings hope

For those of you who follow bird news around the globe, you are probably aware that vulture populations have crashed to an unsustainable level due to the widespread use of the veterinary medicine, diclofenac. Three species of vultures- the White-Rumped Vulture (Gyps bengalensis), Indian Vulture (Gyps indicus) and Slender-billed Vulture (Gyps tenuirostris) declined by more that 95 percent in just three years in the 1990s and their populations have been declining by 22-48% since then. The populations are so low now that the species’ survival depends mainly on captive breeding success.

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Birdlife International just issued a press release that a single White-rumped Vulture chick just hatched at one of the breeding centers. This early success is good news and means that hopefully the captive breeding program can continue at an accelerated rate. Also in the good news column is the fact that diclofenac is being phased out quickly in India and surrounding countries in an attempt to save the remaining wild populations of these birds that were once so common.

Read the press release here.