02 October 2015

Miller Beach Herring Survey

It's difficult to be certain when contingents of new Herring Gulls begin arriving on the very southern tip of Lake Michigan. Based on the last few years of monitoring this region, I'd put the date at about September 10th. The numbers slowly build throughout the month, but it's not until late October that a much more significant wave is noticeable. Interestingly, Lesser Black-backed Gull numbers nicely parallel the increase in Herrings. Maybe one day I'll try to calculate a constant of variation from season to season.

The challenge in getting an accurate picture of what's taking place is that the birds may be out feeding on the lake at different times of the day (or week) depending on weather conditions. Some are also tucked away at the local landfills.

So as I've tried for the last 4 years, I got out this week on 3 consecutive days (29-30 September and 01 October) and focused primarily on the beach gulls, each day for 2.5 hours, at the same time of day (late afternoon). This year I chose Miller Beach in Gary, Indiana, mostly because all 3 days would have the same weather pattern (temps in the mid-60s, with NE winds at 15-25 mph). On all 3 days I had "different" individuals that weren't observed on any other day. Numbers were higher on 30 September than the 29th of September or the 1st of October.

The numbers here pale to the hundreds of Herrings seen at Michigan City and New Buffalo, but still, I was interested in seeing if the constant northeast winds would usher in hoards of Herrings off the lake. Not so. My high count on 30 September was a meager 15 Herring Gulls (4 adult types, 2 third cycle types, 3 second cycles, and 6 first cycles). My 3 day total, counting new birds, was 31. Oddly, it seems the northeast winds moved the birds out, more than anything. Perhaps this is a "transitional period", where our Lake Michigan birds are moving out, soon to be replaced my northern Lake Michigan birds.

Speaking of northern Lake Michigan Herrings, I'm under the impression that the majority of our birds must originate from the Door County, Wisconsin colonies and points northeast of there, throughout the UP of Michigan. Indeed, most of the banded gulls I've found down here would support that. One conjecture I might make is that the colonies to our north are dense and so younger adults (non-breeders?) stay here near a centralized feeding hub (Berrien County, MI) and then relocate as they age. Beside the outlier (29 years and 3 months) that I found a couple of weeks ago, all of the other banded "adult" Herrings are relatively young (over 90% less than 6 years old).

On With Some Photos

Despite only having a small group of HERGs to work through, I did find 4 "cool" birds to share.

Bird #1

A hatch year individual with a completely bi-colored bill. The sharply demarcated black tip is an unusual pattern for September - maybe the first I've seen like this at this date.
Gary, IN. 30 September 2015.

Same individual above. Typical Smithsonianus tail pattern. First generation flight feathers. Nearly 100% post-juvenile scapulars.

Bird #2

A not so uncommon plumage aspect for this time of year, except for the very dark (nearly black) scapular centers. If this pattern was a bit more consistent throughout the rest of the back, one might start to think a black-backed parent was involved.

Bird #3

My favorite bird from the last three days. The wing coverts are faded and already bleaching. Some of the scapulars are showing very dark brown/black bases, and best of all, the pale primary tips make a bold statement. This looks much more like a "strange" Herring I'd expect to see on Florida's coast in mid-winter. I'm eager to see if this bird sticks around for a couple of months.

Bird #4

This one would not allow close approach. It's not so much the standing bird that intrigued me, it's the pale base to the uppertail coverts (see next photo).

Relatively narrow tail band and white ground color to the uppertail. Also interesting is the darker window on the inner primaries. The lack of contrast here can partially be attributed to lighting. Another reminder of how a single photo doesn't always reveal the entire "picture".
Same individual above. Still, a relatively dark window but the wing is closing (hence, the paler inner webs to the inner primaries are somewhat concealed). The uppertail pattern is not an illusion. This is a pale tail for any Smithsonianus. "Plain" and simple!

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