28 July 2015

July Lesser Black-backeds on the Cape Cod Peninsula

The frequency at which Lesser Black-backed Gulls are being seen along the Atlantic coast in the summer months continues to steadily increase. There are some sites where the species is locally abundant and is found in the hundreds (such as Chincoteague NWR in Maryland and Virginia). But at other sites, Lessers tend to be unpredictable, seen by the tens and even hundreds one week, and then all but non-existent the next week.
Some of this may be due to observer-bias, but also likely is a rapid turnover rate as the species moves out at sea or up and down the coast in search of a food source.

Similar to when I wrote about the status of LBBG in Birding magazine a few years ago, the age distributions are still consistently in favor of young birds - mostly 1-2 year-olds in the midst of complete molts. Rarely do I find evidence of definitive adults being recorded in the breeding season.

23 July 2015

Summering Black-legged Kittiwakes in Provincetown

Unprecedented numbers of Black-legged Kittiwakes - all first summer individuals - have been summering on the northern-most point of the Cape Cod peninsula. I had the opportunity to spend some "quality" time with a group of no less than 24 birds at Race Point Beach last weekend in Barnstable County, Massachusetts. All photographs taken here were on 18-19 July 2015.

Most upperwing coverts molted, bills have turned mostly yellow and the hind-neck collar is all but non-existent.

22 July 2015

Off-island Resights of Herring & Great Black-backed Gulls: Mid-July

While working my way up and down the Massachusetts and New Hampshire coast last week, I found several off-island Appledore gulls.

Herring Green 42A. Banded as a chick on 18 July 2014. Seen here on 16 July 2015. Rockingham Co. New Hampshire.

Great Black-backed with Pseudo-Mirror on P8

Not too many large white-headed gulls develop a 3rd mirror on the 8th primary. Common Gulls regularly do, but Great Black-backeds??

Olsen and Larsson note that about 10% of males and less than 1% of female GBBGs develop a small mirror on P8 (~35mm in males and ~10mm in females). Simply put, it's not commonly seen by most field observers. So I was super excited when I found this bird circling "The Devil's Dance Floor" on Appledore Island recently:

Adult GBBG with triangular-shaped mirror on p8 and two white tips to p10 and p9. Notice the relatively thin white tips to the inner primaries when compared to the mid-secondaries. This is quite different than Western, Slaty-backed and Kelp Gulls.
I'd give up chocolate for the rest of my life to know how old this individual is and how this primary pattern progressed as it aged.

Deviate Leg Color in Adult-type American Herring Gulls

It seems too often birders are confused by adult type Herring Gulls with unfaithful leg color. It's known that Herring is a pink-legged species, but the Spring and Summer season often produce some interesting leg patterns.

We Like Normal

Adult-type Herring Gull with typical pink-colored legs. Daytona Beach Shores, FL. January 2015.

A Herring with Yellowish Legs?

A not too uncommon leg color one may find is a pale straw-yellow:
Adult-type Herring with an obvious yellow tinge to its legs. Portsmouth, NH. 16 July 2015.

Bruised and Battered

The other deviate leg color is a cold bluish-gray, like this:
Adult-type Herring with bluish-gray legs. Portsmouth, NH. 16 July 2015.
Variation in large white-headed gulls is wide, and it's unfortunate that some would rather invoke the "hybrid" or "rarity" label when encountering birds like this. Why these birds develop such leg colors is not fully understood but I have a few theories.

The former bird with yellow legs is a color one will most likely see in early Spring. The latter, with bluish-gray legs, is a color that is noted frequently with Herrings along the Atlantic coast. This might suggest that those with yellow-colored legs develop via hormones, whereas the bluish legs may be related to a food source on the Eastern seaboard.

21 July 2015

Gull Banding on Appledore Island

I had the honor of visiting Appledore Island off the coast of Maine/New Hampshire last week. The 95 acre island is the largest of a cluster of islands in the Gulf of Maine, referred to as The Isle of Shoals.

Appledore Island - Copyright Shoaler

Trolling into the dock on a zodiac. Photo by Bill Clark. 
Admittedly, this trip was long overdue. The lure for me is an extensive banding program that uses large, colored, field-readable bands on Herring and Great Black-backed Gulls - a rather unique project that's unmatched in the United States when it comes to gull banding. Dr. Julie Ellis of Tufts University began banding gulls here in 2004 and she's spearheaded the program since. The program is contributing much information on the migratory patterns, survival rates and behaviors of these birds.

06 July 2015

First Weekend of July: Lake Michigan

03 July 2015 - Greg Neise and I made several stops along the Wisconsin lakefront (Port Washington, Sheboygan, Manitowoc and Two Rivers). The season is getting progressively worse with little to no gulls in Port Washington and Sheboygan. This is almost certainly due to the lack of fish die-off.

The gulls at Manitowoc weren't using the south pier when we arrived, but there were gulls on the two defunct cribs south of the south pier, including 2 Great Black-backeds (1st/2nd summer types) and a Glaucous Gull (2nd summer type). We also had our first juvenile Herring of the season (a tad early for a fully fledged HERG to be flying).

02 July 2015

Juvenile Versus Formative Feathers in Juvenile Ring-billeds

The upperparts on juvenile Ring-billeds take on a vast array of brown, black and tan patterns. But they often show a silvery-gray, to some degree. This silvery gray coloration is not acquired via feather replacement, but rather, is inherent in juvenile plumes.

For instance, it's not unusual for fledglings to show an entire row of grayish greater coverts, like this bird:

Juvenile Ring-billed Gull. Blue Island, Illinois. 04 July 2013.
These gray feathers are not 2nd generation (i.e., formative), but rather, juvenile (=1st basic).

Looking closely at the other wing coverts and scapulars, you'll notice they too have grayish centers and bases as well.

Juvenile Ring-billed Gull. Tinley Park, Illinois. 26 June 2014. Showing a couple of lesser coverts with gray coating, and almost the entire row of greater coverts with a silver-gray (juvenile feathers).
Juvenile Ring-billed. East Chicago, Indiana. 27 June 2015.
Notice on the open wing above the entire row of greater coverts with a silvery base. This is complemented by a similar color/pattern on the inner primaries and outer secondaries - all 1st basic, juvenile, feathers.

I've wondered why some juveniles show this gray color more than others. The simple answer is "variation". It does however seem more common as we get later in the season (late July and August). It could be birds that fledged a bit later develop adult-like colors (as is the case in late molters in 2nd cycle large white-headed gulls).

But I do have a few examples of juveniles that show gray greater coverts in mid-June. My earliest inland juvenile (away from Lake Michigan) is this bird:

Juvenile Ring-billed Gull. Tinley Park, Illinois. 16 June 2015.
The bird above is remarkable in that it shows gray on the edges of the two lower tertials in mid-June.

Another loose theory of mine is that the wing coverts and scapulars pack more gray in their centers. As they begin to show the slightest amount of wear, the gray appears to widen and the buffy edges diminish. This can only be a function of time, as feathers loose their paler edges via wear as the weeks progress. Take this bird, for instance:

Juvenile Ring-billed. Chicago, Illinois 26 July 2013. Intricate gray centers to most of the greater coverts, and again, along the bases of the lower tertial edges. Will this gray widen  as the edges begin to wear? 
Juvenile Ring-billed Gull. Chicago, Illinois. 26 July 2013. An atypical individual with white primary tips and boldy checkered upperparts. Still, grayish/white centers can be seen on many of the lower scapulars and wing coverts.
Juvenile Ring-billed Gull. 26 July 2013. A unique "ghost-type" with silvery greater coverts and whitish triangular centers to the scaps and lesser/median coverts.

It should be apparent to the careful observer when "true" post-juvenile gray feathers have molted in.

Ring-billed Gull undergoing prefomative molt - no longer juvenile. East Chicago, Indiana. 24 August 2015.
Only a few juvenile scapulars remain (the 3-4 lower feathers with brown centers). The upper tertials are also juvenile, while the lower 2 are entirely gray with white edging. These lower tertials and gray scapulars are 2nd genration feathers acquired via a preformative molt - a partial molt contained in the first plumage cycle. Note though that the greater coverts with their silvery-gray coating are juvenile feathers.

Although Ring-billeds do often replace upperwing coverts in their preformative molt, it's usually limited to a few feathers here and there (as is the case with tertial replacement), like this bird:

Mostly post-juvenile (formative) scapulars. Several lesser median covets have been molted (gray). But notice how the juvenile greater coverts are mostly brown with very little hints of gray. St. Joseph, Michigan. 01 September 2012.
The scapulars appear to take on the most amount of feather replacement via the PF molt. But there are some extreme individuals that replace tertials (rarely all) and a fair number of upperwing coverts in their preformative molts:

Ring-billed Gull in formative plumage. 31 October 2012. Chicago, Illinois. Upper tertials, all the visible scapulars and many median/lesser upperwing coverts have been molted via the prefomative molt. This individual is rather extreme for any formative Ring-billed Gull in its first calendar year. 
The gray band of greater coverts are juvenile feathers. The back shows a mixture of brown juvenile scapularss and gray formative scapulars. East Chicago, Indiana. 24 August. 2015.