More gullage

Almost two months ago, when I had just started the migration watch on Sandy Hook, NJ, I wrote a little bit about the gull flock on the False Hook ("Gullage"), which at that point had grown to 1000+ individuals. Now, having just finished the count on Sandy Hook, I can look back on a pretty good gull flight this spring, which at the end gets the more interesting species. I missed out on Black-headed Gull this year, but where I'm from that is by far the most common gull, so no great loss for me. Did get Little Gull, lots of Bonaparte's Gulls, and throughout the count several individuals of both 'white-winged' species, Iceland and Glaucous. And of course there was that hybrid gull, Herring x Glaucous.

I want to share some images of an Iceland Gull I photographed last week, some Little Gull shots also, and some images of what I think is probably an aberrant American Herring Gull, but may be something more exciting?

Here's that first-cycle Iceland, in with Herrings and Great Black-backeds. Incidentally, what is the bird on the right? Is that just a bleached first cycle Herring Gull? Or something else? Shame I didn't get the entire bill on that bird, but I was going for the Iceland.

An open-wing shot reveals a tail band stronger than on most immature Kumlien's Icelands, but still within the wide range of variation.

Little Gull is rare but regular in northeastern New Jersey, and the bird found by Tom Boyle last week - I stood next to him when he called it out - stuck around for at least a few days. Saturday, it was joined by a second, more heavily marked individual.

The Little Gull below is less heavily marked, but still separable from the slightly larger Bonaparte's Gull next to it by its shorter legs, more pronounced carpal bar, dark tertials, and zig-zag pattern on the folded primaries.

Also on the False Hook Saturday was this oddball. What is this? At first, you might think Glaucous Gull: a fairly large white-headed gull with white wingtips. But the outer primaries have too much white in them.

The bill has unusual patterning, with a dark line along the edge of the maxilla and mandible.

Take a look at a few open-wing shots. This was the best I could do under poor lighting conditions, in the company of birders that I didn't want to deprive of great birding to be had on the False Hook right then (drake King Eider sitting on the beach, two Little Gulls around, immature Lesser Black-backed Gull, etc). Had I walked up to the bird, I probably would have scattered it and everything else that was there.

I think these open-wing shots show most clearly that this is not one of the more regular 'white-winged' gulls (Glaucous or Iceland).

Note the dark tail band, expected on a third cycle Herring Gull, not on a third cycle Glaucous.

Finally a shot of the bird next to a normal third cycle American Herring Gull. In this shot, there's a subtle yet appreciable difference in mantle color between the 'white-winged' and the normal Herring Gull. The mantle color may be good for Glaucous, but there's other disqualifying marks. So… what is this bird? I don't have access to the Howell & Dunn gull book, so I can't delve any deeper than my admittedly limited knowledge of large white-headed gulls permits. If anyone wants to shine their light on this one, comments always welcome!

On a different note, I want to thank all you Jersey / NYC metro area birders who came to the platform this spring and made my time there more enjoyable. I had a great time, and you made it worth it.

Piping Plover predation attempt?

Piping Plovers eyeballing Red-winged Blackbirds sitting on their predator exclosure

Today I witnessed what seemed like an (unsuccessful) predation attempt on a Piping Plover nest by three Red-winged Blackbirds at Sandy Hook's North Beach. As it was happening in front of my eyes, I tried to grab some video of it.

Just prior to this, I had been observing shorebirds feeding on the sand spit at the 'False Hook'. Nearby, I noticed three adult male Red-winged Blackbirds scavenging the flood line for sand flies, but didn't pay them any further attention.

That is, until I saw them land on one of the Piping Plover predator exclosures and even go inside! The nest owners started calling and tried to scare off the blackbirds with threatening postures and wing spreading. Some of this can be seen in the video (although, regrettably, very little of it remains visible after down-sizing it for online posting). The plovers did not feign injury, as they will do when faced with bigger predators, but simply stood their ground and defended their nest. The blackbirds quickly gave up and left. One of the plovers resumed incubation while the other stood nearby.

Piping Plover incubating inside predator exclosure

The Piping Plover is a federally endangered beach-nesting shorebird, increasingly dependent on management. Conservation efforts toward Piping Plover populations include predator exclosures, sometimes electrified as the ones used on Sandy Hook. A recent paper in Avian Conservation and Ecology reports that predator exclosures enhance reproductive success but increase adult mortality of Piping Plovers (Barber et al. 2010). The exclosure is meant to keep out foxes, gulls and other predators.

The Red-winged Blackbird, one of North America's best studied birds, is primarily granivorous, although animal matter (insects) take up a major percentage of its food intake during the breeding season. It is not known to predate on eggs of other birds, and perhaps what I witnessed was nothing more than three blackbirds being curious about a Piping Plover predator exclosure. I was astounded, however, to see one of them go inside, as I'm sure the plovers were too!

Cited literature:
Barber, C., A. Nowak, K. Tulk, and L. Thomas (2010) Predator exclosures enhance reproductive success but increase adult mortality of Piping Plovers (Charadrius melodus). Avian Conservation and Ecology 5 (2): 6.

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.

An unusual Blackpoll Warbler

 

Yesterday morning I photographed this unusual adult male Blackpoll Warbler in the beach plum behind the north observation deck on Sandy Hook.

It was unusually early, for Blackpolls are normally among the last of the warblers to come through, although not unheard of early.

Assuming this is an adult male (based on its overall color, the strong malar stripe and the unstreaked black cap), it is unusual to show a white eye arc and a white supraloral. None of the guides I consulted mention the possibility of males showing these characters, and I had certainly never seen it before. These are characters more often associated with females of the species.

The throat and malar area look normal for the species. Male Blackpolls often have a few black feathers on the chin, as does this bird.

Here is the bird from another angle. I don't see anything unusual here either.

The bird was by itself and did not vocalize. It foraged quietly for insects in the beach plum.

Does this bird show a mix of mostly male and some female characters? Or is it a hybrid with another species? Or do male Blackpolls sometimes show eye arcs and a white supraloral?

Postscript:
Having thought about this a little more, it seems likely that this bird was not quite finished with its prealternate molt. In basic plumage it has that eye arc and the supraloral. Most wood-warblers have a prealternate molt early spring, as I'm sure does the Blackpoll.

Gambel's White-crowned Sparrow

Gambel's White-crowned Sparrow

Yesterday evening, while birding the Boy Scouts Area on Sandy Hook, I found this 'Gambel's' White-crowned Sparrow, Zonotrichia leucophrys gambelii.  This subspecies breeds on the northern tier from Alaska to Hudson Bay, and winters south through central Mexico, generally rarer eastward (Chilton et al. 1995).

It differs from the here on the Atlantic coast more expected nominate subspecies in having white/gray lores (black in leucophrys), an orange bill (pink in leucophrys), and a dull brown and olive back (ruddy brown and gray in leucophrys).

Here's a (crappy) photo of the nominate subspecies, in which some of these differences can be appreciated. I took this photo in dense fog on the 13th of April, 2011, here on Sandy Hook.

nominate 'leucophrys' White-crowned Sparrow

Compare this to the gambelii subspecies I photographed on Sandy Hook yesterday:

Gambel's White-crowned Sparrow

Since the gambelii subspecies does winter in very small numbers on the East Coast, it's impossible to infer where this bird spent the winter. It could be a western stray, but it could just as well have wintered among nominate conspecifics here in the East.

A detailed study of White-crowned Sparrow subspecies identification, highlighting the complexity of the issue, can be found on David Sibley's blog.

Cited literature:
Chilton, G., M. C. Baker, C. D. Barrentine and M. A. Cunningham. 1995. White-crowned Sparrow (Zonotrichia leucophrys), 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/183
Sibley, D. (2010) White-crowned Sparrow Zonotrichia leucophrys. Blog entry on separation of White-crowned Sparrow subspecies, Sibleyguides.com.

Impressive morning songbird flight

Blue-gray Gnatcatcher

Hot on the heels of a strong falcon flight last Wednesday, today's push of warm Easter weather brought another slew of migrants to Sandy Hook. I had a feeling it could be good, so I went to the observation deck at 7 AM - well before the normal start of the count.

I was glad I did, for those first few hours I saw many, many hundreds of birds fly past the platform. Three species made up the majority of the flight: Blue-gray Gnatcatcher, White-throated Sparrow, and Yellow-rumped Warbler. Gnatcatchers were particularly numerous - far too many to count: I estimated between 500 and 1,000 flew past the platform those first few hours. Many landed in the tree directly behind the platform, some even on the observation deck itself. They were a constant stream, all heading NNW.

White-throated Sparrow

Hundreds of Yellow-rumped Warblers flew by, as did hundreds of White-throated Sparrow. (After the count, during a little 'fun birding' I found several large groups of them scratching through the leaves, with a few White-crowned Sparrows mixed in.)

adult male White-breasted Nuthatch

Nuthatch migration was again evident, with 28 White-breasted and 3 Red-breasted Nuthatches flying past the count site.

Red-breasted Nuthatch

Birders that came up to the platform later all had happy smiles on their faces, as they listed all the first arrivals they had found that morning. Besides Yellow-rumped and Palm, I had Ovenbird, Blue-winged Warbler and Black-and-white Warbler, all near the observation deck. Others had found Nashville, Black-throated Green, and Prairie Warblers, as well as Summer Tanager, Rose-breasted Grosbeak and many other migrants.

Will all those birds be here again tomorrow? A locally well-known birder often says that "the first thing birds want to do when they get on the Hook, is leave". And, with the exception perhaps of some hawks, this has also been my impression. Often they're here today, gone tomorrow.

It looks like the next big wave of migrants can already be expected Tuesday.

Epic falcon flight

adult male Merlin

This afternoon I witnessed a falcon flight of truly epic proportions, one that has not been seen on Sandy Hook within the last eight years, and perhaps never before. The spring hawk watch at Sandy Hook has been going for decades, but hawkcount.org only has data starting 2004 for the Hook, so that's the dataset I'm looking at. There was an exceptional kestrel flight on April 12, 2009, when a staggering 226 American Kestrels were logged as migrants.

Today's count, however, blew that number out of the water: 282 American Kestrels passed Sandy Hook in a matter of hours! At just slightly past the midway point of the season, this is already by far the best season on (recent) record for American Kestrel, with 664 logged so far... and counting!

As expected, Merlin did great too, with 78 individuals counted as migrants. The bird in the photo above landed in the Locust Grove just east of the hawk platform for a photo during the last hour of the count.

Also expected - at least by me - was a Swallow-tailed Kite that made a brief appearance around 4:30 EDT. When yesterday I saw how the weather forecast was shaping up for today, I knew I would have more than a passing shot at getting it. I started the count late, for the Hook was fogged in all morning, but as soon as the fog broke, there were raptors flying. When the flight reached a certain level of intensity, I figured there had to be a Swallow-tailed Kite in there... I spotted the bird lazily circling between the Lighthouse and the Officer's Building, seemingly not in a hurry to go anywhere. However, shortly after it turned around and went back south.

Spring migration of White-breasted Nuthatch

adult female White-breasted Nuthatch

The familiar White-breasted Nuthatch is generally a resident species, with only some northern and western populations undertaking some migratory movements in some years (Grubb & Pravosudov 2008). On Sandy Hook, I've been told by many local birders many times over, the Red-breasted Nuthatch is usually easier to find, and some consider White-breasted Nuthatch "actually a reasonably good bird to get on the Hook". But where I do most of my Sandy Hook birding, i.e. on the northern tip, I always see more White-breasted than Red-breasted Nuthatches. Usually not more than one or two, though, and certainly not every day.

Today, however, migrant "WB Nuts" were everywhere, and I tallied a total of 30 individuals flying past the platform, all headed to the very northwestern tip of the Hook. Several landed in the tree behind the observation deck, and one even landed briefly on the deck's information panel. The majority were tree-hopping. Others were higher, a few even at a considerable height. What would they do once they hit the northwestern tip and see all that water, I wondered? Would they turn around, like raptors often do? Or would they gain more altitude and just go for it? I never saw them come back, so I assumed most of them were actually making the crossing.

For such a familiar species, surprisingly little still is known about the White-breasted Nuthatch, particularly regarding seasonal distribution patterns. Irruptive fall movements have been noted; for example, nearly 300 individuals were tallied during the fall of 1968 at the Bake Oven Knob hawk watch in Pennsylvania - against only 53 in all previous fall seasons of 1961-1967 combined (Heintzelman and MacClay 1971, cited in Grubb & Pravosudov 2008).

Summarizing this and other largely anecdotal accounts - all from fall seasons - Grubb & Pravodusov (2008) theorize that these movements possibly consist of juveniles, which they feel would explain why there is "little evidence of a return spring migration in this species".


Ron Pittaway's Winter Finch Forecast 2010-2011 mentions the Red-breasted Nuthatch's latest irruption, which was well underway by late summer 2010, but doesn't talk about the WB Nut.

eBird's monthly maps do not reveal a spring migratory pattern either.

Several birders who came up the platform today mentioned they had found multiple WB Nuts while birding the Hook for morning songbirds. So it wasn't like the same three birds were flying circles around the hawk platform, there was actual movement, noted by multiple observers. Detected movement was strongest during the first two hours of the count (between 8 and 10 EDT) but went on until late morning, early afternoon.

So where did today's birds come from? And where are they going?


Cited literature:
Grubb, Jr., T. C. and V. V. Pravosudov. 2008. White-breasted Nuthatch (Sitta carolinensis), 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/054
Pittaway, R. (2010) "Ron Pittaway's Winter Finch Forecast 2010-2011", published on eBird's web site

White-winged Gulls

Glaucous Gull

Following up on the previous post, that same gull flock from which I pulled a putative "Nelson's Gull" last Wednesday today had both white-winged species, Glaucous and Iceland Gull. The two Glaucous and one Iceland I saw all seemed 'pure' individuals;  the hybrid "Nelson's Gull" was not  relocated.

Glaucous Gull with Herring Gulls

For that matter, neither were the two Lesser Black-backed Gulls I found in that same flock on Wednesday. I suspect this flock has a huge turnover, and virtually anything could show up here. It comprises mostly Herring Gulls (70%, I estimated), with Great Black-backed and Ring-billed Gulls present in smaller numbers.  I tried counting the flock on the east side of the False Hook, and came up with 1,400. Several hundreds more were situated on the western side of the False Hook, but by the time I got there, substantial reshuffling had taken place and an additional count seemed futile.

Glaucous Gull, with Manhattan and Coney Island in the background

All too often, I hear birders dismiss the gulls as "too difficult". There is of course a bewildering variation among immature Herring Gulls, which some find intimidating and others a huge turn-on. But the two 'white-winged' species, Glaucous and Iceland, stand out and are easily found in a gull flock.

Iceland Gull, not exactly hard to spot in this flock

This flock may well have other species less easy to pick out. The weather forecast for tomorrow is strong on-shore winds, so the best birding on Sandy Hook tomorrow will likely not be provided by the raptors, but by the gulls.

Nelson's Gull

Today, Sandy Hook was shrouded in dense fog, which gave me a day off from hawk counting and provided me with an opportunity to scour the Hook in the mist for birds. The northern tip of the Hook is never so wildly beautiful and mysterious (and devoid of people) as in dense fog.

At the very tip (the "False Hook") I found this unusual-looking gull. At first I thought it was a Glaucous Gull, but I quickly realized the wingtips were too dark for that species. Somehow the bird seemed too light to be a Herring Gull. Not knowing what I was looking at, I decided to try for some photos.

I now believe it to be a first cycle 'Nelson's Gull', i.e. a hybrid between Glaucous Gull and American Herring Gull. It shows a mix of characters from both species, and Howell & Dunn's authoritative Gulls of the Americas (2007) lists that combination under the header "widespread hybrids". Confirmed interbreeding occurs in the Mackenzie Delta, Northern Territories, Canada (Howell & Dunn 2007), a potential source for this individual.

I also considered first cycle Slaty-backed Gull and first cycle Thayer's Gull, but Glaucous Gull x American Herring Gull seems a better fit. Especially the crisply bicolored 'Glaucous type' bill does not fit first cycle birds of either species, but is good for 'Nelson's Gull'. There's other disqualifying field marks. I do confess I am not a larophile, so I welcome discussion of the finer ID points from the initiated.

Cited literature:
Howell, Steve N.G. & Dunn, Jon (2007) Gulls of the Americas. Peterson Reference Series, Houghton Mifflin Company, New York.

First wave of warblers

Palm Warbler

The first wave of warbler migration has reached Sandy Hook: yesterday there were tens if not hundreds of Palm Warblers throughout the Hook, with some Pine Warblers here and there. Another warbler - Common Yellowthroat - was heard singing from across North Pond both Sunday and Monday mornings, but on Tuesday appeared to have moved on. I found two American Bitterns in its place. Myrtle (Yellow-rumped) Warblers have been around a bit longer, in fluctuating numbers. We haven't really had a big wave of them yet.

adult female Pine Warbler

Orange-crowned Warbler and Black-and-white Warbler have also been reported, and very soon warbler variety will pick up even more, as the other species cannot be far behind now. Possibly the next warm front will bring them to Sandy Hook.

Right now, the Hook is dripping with Slate-colored Juncos, Ruby-crowned Kinglets, Palm Warblers, Hermit Thrushes, Blue-gray Gnatcatchers, Savannah Sparrows, Chipping Sparrows, and Song Sparrows. All these birds are here in good numbers at the moment, and are easily seen.

Great kestrel flight

The second warm front in a fairly short time brought a second wave of American Kestrels passing Sandy Hook yesterday. On the 6th I had 67 kestrels; yesterday I got to 155. This is a respectable number, but by no means a record, for 2009 had 226 and 2008 had 179 for single day counts at Sandy Hook. Most recent years, however, the peak flight of the American Kestrel here has been double, not triple digits. This species is in decline throughout the Northeast, even though largely sedentary urban populations seem to be doing fine.

Like other falcons, American Kestrels are often midday or afternoon flyers, and indeed the majority of these birds passed in the afternoon.

Good early April hawk flight

A pretty good early April hawk flight was seen at Sandy Hook today, with good overall variety and a particular strong showing of American Kestrel. Several Red-shouldered Hawks, including at least two adults (one of which is pictured above), were noted, although none were seen leaving the Hook. That's good news for those of my readers who want to see Red-shouldered Hawks but weren't able to make it to Sandy Hook today.

The falcons of course did not linger. Most of the falcon flight was made up of American Kestrels, but there were a few Merlins also and even a Peregrine Falcon.

Last year, the peak flight of American Kestrel occurred on April 6, back then with 85. Today, exactly a year later, I got to 67 kestrels. Last year, I had a small wave of first migrant Merlins also around this time, with 13 on the 6th, 8 on the 7th and 21 on the 8th. That was 42 Merlins in three days - a wave that, curiously, no other hawk watch recorded. This year, I had 13 Merlins on the 4th, none during the 2 hours of counting on the 5th, and then today just 3. It will be interesting to see if this wave of kestrels is followed by a smaller wave of Merlins in the days ahead…

Browse last year's Merlin posts here.

Northern Saw-whet Owl

I got up a little earlier than usual this morning, to help bird bander Tom Brown with some Northern Saw-whet Owl banding here on Sandy Hook. Tom has been banding songbirds on the Hook and elsewhere in the metropolitan area for years, and last fall started banding at night here on Sandy Hook with an audio lure for saw-whets. He caught more than he expected back then, and this spring is trying again for saw-whets. The individual shown above was his third this spring. We aged it as a second year bird, so born last year.

We wondered if severe winter weather was responsible for the contrast between the fall and spring numbers of saw-whets.

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

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.