Spring season nearing its end

juvenile Bald Eagle

The Sandy Hook Migration Watch began its last week of the spring 2011 season today, with a sum total of zero raptors. Clear skies and calm weather this late in the season usually translate into minimal raptor migration; only a weather event (i.e. a front passage) may trigger some concentrated movement at this point in time.

Looking at the weather forecast for the rest of the week, a major hawk flight seems rather unlikely, and a surprise appearance in the form of a kite is really the best that can be hoped for.

It's not too premature then to look at the Sandy Hook spring 2011 season and see how it measures up against previous years.

Some species did exceptionally well, like Bald Eagle and American Kestrel. Other species, like Northern Harrier, Red-tailed Hawk and (especially) Cooper's Hawk had lower than average numbers this year.

Bald Eagle numbers are increasing everywhere, so no surprises there. But high numbers for a regionally decreasing species (American Kestrel) and low numbers for an increasing species (Cooper's Hawk) highlight the fact that isolated count results from just one year and just one site are of limited value. Weather is always a key factor that determines how many migrants are seen at a monitoring site, and some years the migration of certain species happens to be more coastal, while in other years inland routes are chosen. Or, on light winds or tail winds, the flight can be extremely high and over a broad front, beyond the vision of the observer on the ground. All these things are into play, and produce annual fluctuations.

With longer data sets, however, population trends become measurable. See HMANA's* Raptor Population Index program for an analysis of such trends.

* HMANA = Hawk Migration Association of North America

How I got into birding

 

This beautiful, almost full breeding plumage drake King Eider was found on the beach at the 'false hook' on Sandy Hook today. When word reached me about this bird on the hawk platform, I didn't have to think long about packing up my stuff and going out there. As I reached the end of Fisherman's Trail, the sight of a group of birders with their scopes all pointed in the same direction was a hopeful sign and sure enough, there it was. This is likely the same bird that was found more than a week ago in Horseshoe Cove, elsewhere on the Hook.

King Eider is probably a little less rare here than it is in western Europe, but when I started birding, King Eider was the first true rarity that I saw. I must have been 14 or 15 years old. For a long time, it remained for me the emblematic rare bird, an arctic visitor so beautiful it looked out of place in the industrialized Dutch seaport's harbor of IJmuiden. Since that memorable first bird - also a drake in near-breeding plumage - I have seen a few others, in duller plumages.

Eventually, a juvenile Bald Eagle spooked it; the King Eider flew off toward the ocean, and for all we know may now finally be on its way to the high arctic.

Bald Eagles

This morning, a subadult (4 year old) Bald Eagle was sitting in the tallest tree on Sandy Hook, somewhere between Officer's Row and the Coast Guard Station. While it was feeding on a fish it had caught, it was mobbed by Fish Crows, Herring Gulls and an Osprey.

The eagle was clearly too close to the Osprey's nest on a nearby chimney.

The Osprey persuaded the eagle to leave the area. It flew south, and I decided not to add it to the count. It was probably a 'local' eagle from one of the nearby rivers. Eagle movements over the Hook tend to be irregular and nondirectional: some will be migrants, some will be local birds wandering.

This juvenile Bald Eagle was probably a migrant, although it didn't exactly fly over in a straight line either. In fact, it harassed that same Osprey, which was flying toward its nest with a fish. The Osprey dropped the fish and went after the eagle. The eagle flew up to the tip of the Hook, turned around, and later tried a second time. Sometimes, young Bald Eagles show some fear of water.

This Osprey will likely have more raptors flying over its nest this spring.

Started on Sandy Hook

This week I started the migration watch on Sandy Hook, NJ. I did this count two years ago, when I exposed myself to what seems in retrospect to have been two months of rain and cold with biting east winds coming right off the Atlantic, and long stretches with no birds. Already I feel like this year is going to be different, because today, on what's only the third day of the count, I was able to be on the platform in T-shirt. And there were even some birds to be seen, like this rather pale Red-tailed Hawk.

Best bird today was this immature Bald Eagle. These days a fairly common sight at many hawk watches, but for the Hook still a pretty good bird. Seasonal totals here run between 10 and 20 for this species.

Accipiters (like this Cooper's Hawk) are more numerous at this site.

This is the time for Red-shouldered Hawks to migrate through. Sandy Hook being a peninsular site, many buteos of course don't make the crossing. Today I did see a few going high enough for a serious attempt.

Interesting non-hawks this week included an Iceland Gull on the North Beach and an immature male Common Eider on the bay side, across from the bird observatory's office. Northern Gannets are curiously absent.

In the north country

A couple of days ago I arrived in northern Michigan, where I will be counting migrating raptors at Whitefish Point. This is the name of a small peninsula that juts out into Lake Superior, which still has a lot of ice floating around. Barely visible in the background of this picture is Canada, about 17 miles away.

The raptor season here runs from March 15 until May 31. Most of Michigan is now snow free, but here on the Upper Peninsula, things are still quite wintry. Locals tell me that the weather we’re having is exceptionally balmy for this time of year, but for this counter, who spends his winters in the tropics, it sure feels cold. But it’s a beautiful spot.

Of course there’s interesting northern birds around here, such as Common Redpolls, Pine Grosbeaks, Snow Buntings, and White-winged Crossbills.

Also here in good numbers are Pine Siskins.

The raptor flight this early in the season is dominated by adult Bald Eagles. Today I counted nine migrating balds, including one juvenile and a so-called ‘sub-adult III’ type of bird, or near-adult; the rest were adults. For residents we have at least one adult and one distinctly marked juvenile around the Point – I see them all the time.

This adult female Northern Goshawk, seen this morning and here photographed flying away, appeared to be outfitted with a radio transmitter. It would be interesting to find out whose bird this is, where it came from, and where it is headed.