Thursday, March 31, 2011

Sandy Hook March: the count so far


Non-birders visiting a hawk watch usually ask the hawk counter "how do you know you're not counting the same birds?" It's a great and absolutely valid question, nowhere more so than at a peninsular site like Sandy Hook. Yesterday, on light, variable winds, many raptors got up very high in thermals and left the Hook in northerly direction, headed either north for Brooklyn's Coney Island (10 km) or northwest for Staten Island (12 km). Sometimes - but not yesterday - birds will cross northeast toward Breezy Point in Brooklyn (9 km).

But I've only seen them leave the Hook that way a couple of days this season. A much more common scenario is for birds to fly up to the northern tip of the Hook, see water, and turn around. They really need thermals and light tail winds or light head winds to make the jump over New York Bay.

I do count these birds that fly up and turn around, because they are migrants after all, even though I know that many of them will try multiple times. Some individuals can be recognized by a missing flight feather or a specific plumage, while others may be counted double that way.

Birders visiting the hawk watch usually ask me "how is the season so far?"

With the last day of March a rainy day here (no count), let's take a look at the numbers so far. Bear in mind this possibility of double counts, but consider this a constant effect from year to year.

This March I counted 379 raptors, representing 13 species. Best bird no doubt was an adult Northern Goshawk on the 18th of March, the second day of the count. The season so far has been reasonably good for Osprey (23), Bald Eagle (4), Sharp-shinned Hawk (65), American Kestrel (22), and Merlin (4). Buteos did not do so well in March.

I graphed out the seasonal March totals for Sandy Hook:


Parts of March were rainy, and 5 days of the count were missed so far due to rain. Looking at number of raptors per hour, March 2011 wasn't so bad - third best of the last eight:

Source: www.hawkcount.org

Sunday, March 27, 2011

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.

Thursday, March 24, 2011

Gullage

Nasty weather apparently brought large numbers of gulls to Sandy Hook, for today there were an estimated 1,200 gulls on the North Beach where until recently only two to three hundred could be found.

As their numbers increase, so does one's chance of finding gulls that aren't Herring, Great Black-backed or Ring-billed. Tuesday I found an adult (Kumlien's) Iceland Gull in the flock. Today I found both white-winged species and a Lesser Black-backed Gull.


One of today's photos has two of those additional species in it; the other photo has the other species. I'll leave it up to you to sort through the gullage and find them.

Wednesday, March 23, 2011

Piping Plover courtship display

Snow, sleet and rain kept me indoors most of the day, although I did venture out on the beach at Sandy Hook this morning for a quick look to see what's doing.

At the end of Fisherman's Trail on North Beach, three Piping Plovers were engaged in courtship display. I saw a male doing an aerial display, which involves a circular flight with sometimes slow, exaggerated wing beats and much calling.

video

That male landed not 10 meters in front of me, where a female was standing. The other male, which had also been calling and flying around, left. The remaining male continued his courtship display.

The next step, after aerial display, is the so-called nest-scraping display, in which the male leans forward, pushes his breast into the sand and shakes around a bit, thus creating a small depression in the sand. Listen for his calls as he does this, the calls are part of the display. First we see him remove small pebbles and shell fragments from that area. He'll create several nesting depressions in his territory, one of which may be chosen by the female as the eventual nest site.


video

Next, he will do a tilt display: he'll bend over, opens his wings a little and spreads his tail; the female crouches under his spread tail. I saw this behavior a couple of times.


video

The next step in the display is a hilarious, pre-copulatory goose-step that the male performs. He'll walk up on crouched legs toward the female, then completely changes his posture to standing very erect, showing off his breast band. In this position, he'll start tapping his legs.

video

Apparently, this can go on for several minutes and is usually followed by copulation (Elliott-Smith & Haig, 2004), although I did not see any copulation this morning. In this fragment, she just walks off, and he goes back to removing bits of shell and pebble.

I was delighted to observe this elaborate courtship behavior today, and felt lucky to capture some of it on video. The clips shown here are small fragments of longer, much higher-quality footage and were drastically down-sized for web viewing.

Still better of course is to go out and see this for yourself. Now is really the time to come to the Hook and look for them. These shenanigans will likely be going on for the next couple of weeks or so. Once they have eggs, they will be less conspicuous. Just remember to be mindful of the birds, don't disturb them, and respect the boundaries of the marked-off areas on the beach. The Piping Plover's IUCN status is Near Threatened, with an estimated global population of about 6,000 individuals.

Cited literature:
Elliott-Smith, Elise and Susan M. Haig. 2004. Piping Plover (Charadrius melodus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/002

Monday, March 21, 2011

Piping Plover


Sandy Hook's flagship bird: the Piping Plover!


Numbers on the Hook are building and soon the first nests of the season will be found. Now is really the time to go look for them, when the males whistle their melodious calls and charge with puffed up feathers at competitors.

Sunday, March 20, 2011

Light migration

Today I saw something you don't see very often on Sandy Hook: raptors getting up in thermals and crossing New York Bay toward Coney Island in Brooklyn. Many times, hawks and vultures will come up to the tip of the Hook, see water and turn around. Local conventional wisdom holds that northeast winds are worst for hawk migration over the Hook, but given sunshine and the resulting thermals, light NE winds apparently enable raptors to get a bit of lift from light head winds, just enough to make the crossing.

The Osprey pictured above did that, as did several Turkey Vultures and a couple of immature Red-shouldered Hawks. These birds got high enough and did not come back.

The weather forecast for the rest of the week looks bleak: rain and snow, and unfavorable winds. The next warm front seems to be more than a week away; when it gets here, it should bring a batch of new arrivals in.

Thursday, March 17, 2011

Back on the Hook

Today I started the migration watch on Sandy Hook (New Jersey), which runs between mid-March and mid-May. Sunny skies and light westerly winds made for pleasant hawk watching, even though the numbers at point in the season remain modest. Turkey Vulture was the most numerous migrant (26), followed by Sharp-shinned and Cooper's Hawks (5 of each), Northern Harrier (4), Red-shouldered Hawk (3) and Red-tailed Hawk (1).


This immature Red-shouldered Hawk came in low for a few shots.


An early migrant this species, most of the adults will likely have passed already.

Monday, March 7, 2011

Wintering warblers

first winter female Magnolia Warbler
Yesterday morning, Oliver, Roselvy and I went out again to bird Zamorano University campus, like we did the week before. This time we explored a couple of new spots and 'ticked off' now expected species at routine spots. Thus, we got to 101 species by 10:30 AM already. A number of birds were new, obviously, and there were also a few obvious misses (like Common Tody-Flycatcher, for example).

We did especially well on warblers. Some are common winter visitors here, like Magnolia Warbler, Yellow Warbler, Common Yellowthroat, Northern Waterthrush  and American Redstart. Others appear to be scarcer in the Yegüare Valley, where Zamorano is located, like MacGillivray's Warbler, Yellow-breasted Chat, Ovenbird, Lousiana Waterthrush, Black-and-white Warbler, Wilson's Warbler, and Tennessee Warbler (these last three more common in the surrounding pine-oak forests). Gray-crowned Yellowthroat is resident here.

New birds on our campus list included Bare-throated Tiger-heron; Green Heron; Blue-winged Teal; Crested Bobwhite; Belted, Amazon and Green Kingfishers; Tropical Pewee; Blue-headed Vireo; Masked Tityra; Grasshopper Sparrow; and a few of the warblers mentioned above.