19 August 2014

American Herrings on Lake Michigan: mid-August

Here's a small collection of American Herring Gulls photographed 5-12 miles offshore from Berrien County, MI. The birds were photographed from a boat with a crazy mix of weather conditions, beginning with partly cloudy skies, bright sunshine, heavy overcast and then intense fog. As is typical on these boat trips, we begin with more Ring-billeds 1-2 miles from shore, and then transitioned to a majority of Herrings at about 5 miles.

Juvenile (HY bird). 17 August 2014.
Juvenile (HY bird). 17 August 2014.

Likely an individual molting from 1st cycle to 2nd cycle (2nd CY). The inner primaries are adult-like and there is the possibility that this plumage is a retarded 3rd basic type. 17 August 2014.
First summer (2nd CY). Second prebasic molt is nearly complete. 17 August 2014. 

Another individual with somewhat advanced inner primaries (note the prominent white tips on p1-p2), but my impression is that this is a first summer bird molting into 2nd basic. 17 August 2014.

A second summer individual molting from 2nd basic to 3rd basic (3 CY). 17 August 2014.
Same individual above.

A second summer bird molting from 2nd basic to 3rd basic (3 CY). 17 August 2014.

Adult type. 17 August 2014.
At approximately 12 miles from shore, we lost ALL of our gulls (despite still providing chum). The heavy fog might be the reason why the birds dropped off, or perhaps it's a simple "cost-analysis" solution that the birds have worked out in the summer months.

09 August 2014

Great Black-backeds: Juvenile Versus 1st Summer Birds

My short semi-annual runs to the East Coast are usually just enough time for me to visit the most popular gull hangouts between Chesapeake Bay, Delaware Bay and Cape May. Early August is the best time of the year for me to get my fill of Great Black-backeds, a species I don't regularly see in large flocks. Below is a collection of GBBGs photographed on the beach adjacent to the South Cape May Meadows. The focus of this post is separating 1st summer and juvenile types - a task not too difficult.

Great Black-backed (juvenile ~2.5 months old). Cape May, NJ. 07 August 2014.

Great Black-backed (1st summer ~14 months old). Cape May, NJ. 07 August 2014.
The 1st summer bird above is aged (at this time of year) by the relatively white head, paling bill, and plain upperparts (compare the greater coverts of both birds above, for instance). Also, the very short wing projection on the 1st summer bird is shorter than what we'd find on most fledgling juveniles by this date.

Juvenile (standing) with 1st summer bird (resting). Note how plain the upperparts are on the 1st summer individual. The juvenile is wearing a much more pristine plumage and is more boldly patterned.
So juveniles are obviously classified as first cycles (juvenile plumage=first basic), but how exactly do we categorize the molt progression of "1st summer" birds? First summer, large white-headed gulls in the northern hemisphere are currently molting from first cycle to second cycle. In this molt, they're typically replacing all of their flight and body feathers via the 2nd prebasic molt (PB2). By mid-late fall most of these individuals are what we'd call 2nd cycles, but right now their plumage is a mixture of 1st generation and 2nd generation flight feathers. A good indicator that the 2nd prebasic molt is complete is when all of the rectrices, secondaries and primaries are renewed and fully grown. It's then generally safe for a field observer to say the gull is sporting its second basic plumage.

Juvenile GBBG. Note how the flight feathers and tail feathers are all intact and neatly arranged. Compare with the first summer bird below.
First Summer GBBG. Sheboygan, Wisconsin. 11 July 2014.
Note the mostly new (2nd basic) primaries on the left wing. This bird has a retained juvenile primary (1st basic) and has dropped most of its secondaries. Much of the underwing coverts have also shed.

Can you age these two?

Certainly not a hatch year bird, right?

As crisp and pristine as can be, this is clearly a recently fledged juvenile - one with little manners.

The paling bill and white head/body feathers signal 1st summer. But also note the molting underwing coverts and old retained outer primary. 
A few older birds just for good measure:
Adult types in heavy molt.

Likely a 3rd summer bird molting into 4th basic. Note the extensive brown tinge to the greater coverts and black on the bill tip. The rather slim neck and relatively "thin" bill suggest a female.

08 August 2014

Juvenile Laughing Gull: Annapolis, Maryland

It's early August and the East Coast is teeming with juvenile gulls. Here's a Laugher that I got pretty decent shots of the other day.

Laughing Gull (juvenile). Annapolis, Maryland; 05 August 2014.
This plumage is incredibly stunning, but moreso when the open wing and fanned out tail are seen together:

Same individual above.
Soon these plumages begin to mature and, well, you know how it goes...

04 August 2014

Late First Summer Little Gulls: Manitowoc

Although Bonaparte's numbers were down to about a dozen or so at the Manitowoc Impoundment, we managed 2 first summer Little Gulls on Friday:

Little Gulls completing 2nd prebasic molts. Also pictured here is a Semipalmated Plover, Semipalmated Sandpiper and Least Sandpiper (bottom left corner). Manitowoc, WI. 01 Aug 2014. 

First summer Bonaparte's are a bit behind Little Gulls in flight feather molt. Consider this one-year old that is still holding on to half of its juvenile (1st basic) secondaries and a few outer primaries:

Boanaparte's Gull (undergoing 2nd prebasic molt). Manitowoc, WI. 01 Aug 2014.
I then made a quick stop to Sheboygan where I recorded 11 Lesser Black-backeds. This is rather extraordinary seeing that Herring numbers were down to less than 75 individuals. Herring juveniles were out and about and fully fledged by now:

Lesser Black-backed (1st summer). This one-year old is just now beginning to show a pale bill base. 

Almost completely done growing all of its flight feathers. It's safe to call this bird a 2nd cycle now.

A rather shaggy and dishevled juvenile American Herring. The tertials and greater coverts are without a doubt the plainest I've seen on a recently fledged Herring. Manitowoc, WI. 01 August 2014.

Small bill on this American Herring is already paling. Note that the bill may not be fully grown yet (as the outer primaries are still growing).

"In Your Face" Juvenile American Herring.

Typical juvemile American Herring for Great Lakes region.

First summer American Herring molting into 2nd basic. 

First summer American Herring molting into 2nd basic. 

31 July 2014

Juvenile Ring-billeds: Late July

A small selection of juvenile Ring-billeds, photographed on the very southern tip of Lake Michigan, in East Chicago, Indiana:

Brown type. East Chicago, IN. 26 July 2014.

Intermediate type. East Chicgao, IN. 26 July 2014.
Besides the subtle variation in the bill patterns, also note the immense differences in leg color, so early on in the season.

Ghost type. East Chicago, IN. 26 July 2014.
Peter Pyle recently informed me that it's not very unusual for juvenile feathers to show color patterns that are found in formative feathers. This adds to the excitement of trying to determine whether some of these feathers are juvenile or not, especially with species like RBGU that begin molting in earnest after leaving their natal colonies. Consider this individual:

Ghost type with a considerable amount of gray juvenile feathers. East Chicago, IN. 26 July 2014.
Here's this same individual with outer primary still growing out:

Note the extensive gray in the juvenile greater coverts and in the scapulars sitting over the proximal side of the wing.
I suspect that 2nd generation feathers (whether replacing feathers that were dropped accidentally or via molt) look longer, broader and tend to be "fluffier", covering a number of smaller adjacent juvenile feathers, like this:

Note the long broad, gray, median covert that has a different pattern than the surrounding "true" juvenile feathers.

The progression of 2nd generation feathers is obvious once it begins. Here are several birds that illustrate this nicely, spanning from August through September of their hatch year - all photographed on Lake Michigan: