25 August 2014

More Herrings and Ring-billeds: Late August

I spent some time studying the growing flocks of juveniles in East Chicago, Indiana yesterday. Same "boring" species but the immense variation in their plumage is far from boring!

Juvenile American Herring. East Chicago, IN. 24 August 2014.

A rather big-eyed look to this juvenile American Herring. East Chicago, IN. 24 August 2014.

Juvenile American Herring. East Chicago, Indiana. 24 August 204.
Interestingly, the three outer primaries appear rounded.
Juvenile Ring-billeds below - how can one not appreciate the incredible amount of variation in a cohort of similar aged birds, all presumably from the same colony?!

Juvenile Ring-billed. East Chicago, IN. 24 August 2014. Cinnamon tones throughout with rather dark tertials.

Below is a juvenile with a remarkably clean underwing. The axillaries and lesser/median underwing coverts are usually edged in brownish black at this age.

For comparison, consider the hatch year Ring-billed photographed moments before the bird above:

The secondary greater coverts on the underwing are typically pale on young Ring-billeds, as is seen in both examples.

Flight shots of juvenile RBGUs:

A presumed 2nd summer completing its second prebasic molt. Some individuals show no mirror and others a relatively large mirrors on p10. This one shows a tiny spot:

2nd cycles usually have "mostly" adult-like gray tertials, but there are individuals with rather "retarded" in black centers, like this bird:

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...