Date: 3/28/18 9:16 am From: Harry LeGrand (via carolinabirds Mailing List) <carolinabirds...> Subject: Re: 5000 gulls, Buckhorn Res. eve. 3/27/18
To follow-up on Frank's questions, and my comments on Ring-billed vs. Lesser Black-backed numbers:
1. In the eastern Piedmont, using data from Jordan Lake, Falls Lake/Beaverdam, Lake Crabtree, and Lake Wheeler this winter:
the typical ratio of RBG: LBBG is about 200-300:1. That is, for every 1000 Ring-billed, you might average about 5 Lessers, at best. I see the all-time high LBBG count in our area was 39, seen by Jelmer Poelstra at Jordan on 25 Feb 2018; at that same spot from Ebenezer Point, he tallied 7,000 Ring-billeds:
I never see Lessers at Beaverdam Reservoir, where as many as several hundred Ring-billeds were present during the winter. Lake Wheeler always has 100 or more Ring-bills in winter, and never a Lesser.
In summary, you can see that, at best, in the eastern Piedmont you would expect to see one Lesser for every 300 or more Ring-billeds, as of this winter.
2. I suggest that Frank has the right idea about feeding habitat for all those Lessers near Buckhorn Reservoir, which is in the upper Coastal Plain. We do know that both species in the inland portion of the Coastal Plain spend much time feeding in croplands during the cooler months, such as around the Beasley Road ponds in Washington County. In the Piedmont, even in the Triangle area, close to the Coastal Plain, *I never see gulls feeding in winter croplands*. I'll leave it to others why that is, such as the crop remains (or insects, etc.) they prefer in winter. In the Triangle, gulls feed: 1) from the surface of lakes and large ponds; 2) at landfills; and 3) at shopping centers (mainly just Ring-billed there). So, Lessers seem to be specializing, if that is the right word, on feeding in croplands in the inner and central Coastal Plain (almost always with many or more Ring-billeds). In the Piedmont, most Lessers are probably feeding at landfills, and secondarily at lakes. Though we do have plenty of cornfields and other croplands still left in the Piedmont (though these are constantly dwindling due to development), gulls don't seem to feed in them here.
Harry LeGrand Raleigh
On Wed, Mar 28, 2018 at 8:41 AM, Frank Enders <carolinabirds...> wrote:
> I was at boat landing 6:48 to 7:07 P. Then waded to shoreline through 6" > deep marsh at 15 mph curve on Bailey Road, and ended looking at upper end > of lake through house lots by7:25 P when too dark to id species. > Differences with Davis's eBird report are that I faiiled to id many > species, had a flock of 8 Horned Grebes, more loons (5), more martins > (50-70 mostly males apparently trying to survive by skimming the water in > the warmer eve, while he had 5, probably most not out of boxes at dawn). > > EXECUTIVE SUMMARY is that his numbers make sense, except that I had about > 5000 Ring-billed Gulls at roost--gulls were coming in from east. > > From boat landing, 20-50 Lesser Black-backed Gull, 400 Ring-billed Gull. > At times no gulls. I do not know where they went when I saw none, perhaps > upstream out of view. LBBG were seen to land for a while on the water, > while Ring-bills were mmore flighty. At one point the gulls may have been > flushed by the noise of some 40 rounds of gunfire from the south shore, but > I think it was just the noise, no shots aimed, since there was a fishing > boat between the shooter and the gulls, which fishers ramined unperturbed. > > From the marshy spot, more of the same (grebes here). > > Looking upstream at end of time, I was surprised to estimate so many gulls > (5000), clearly mostly Ring-bills. > > I do not understand why Davis saw so few--perhaps he was not where I was, > and perhaps the Ring-bills left the lake first in AM. There had been a > recent report of thousands (2000, 3000?) there, but nobody seems to be > reporting manny LBBG anywhere. High count was Horry County Landfill (SC, > 30? 40?). > Perhaps there are mmore reported at Cape Hatteras in eBird for March, > which hotspot I happened not to click on. Incidentally, I first saw > Davis's C-bird post on ABA Carolinabirds, which showed Legrand's comments, > but not Patteson's--- ABA does this on many threads. My direct receipt of > Carolinabirds shows all items in thread, and I will check Hatteras hotspot > birdlists. > > If you figure some 10% of the gulls which I could id from boat landing > were LBBG, then 10% of roosting 5000 gulls means Davis undercounted the 500 > LBBG by about 40%. (THAT IS A JOKE!) In other words, there were about the > same number, probably, of LBBG on the lake at 7:30 PM as at 7:30 AM. > > NEXT QUESTIONS: where are the LBBG in the daytime---in fields off NC 97 > where Davis had seen double digits on occasion? I won't say probably > spread out over any number of such fields in Wilson and Edgecombe Counties. > AND, who will bell the cat? Who will follow the gulls off the reservoir > in the AM (toward east), and who will be able to get to points (dirt road > from north deadends at lake) where they can scope the gull flock for a few > days to see how numbers will drop off? > > The site reminds me of the joke about seeing Collared Dove and Eurasian > Wigeon in this country--just like in overdeveloped rural England! The > mansions around Buckhorn must be like the expensive houses twitcher bird in > suburban England. Big useless lawns which somebody on C-birds recently > complained about. > Close as the subdivisions are to the reservoir, there may be a Jordan Lake > pollution event here. > Does anybody else think that Ruddy Ducks, eating chironomid larvae from > the mud in reservoirs, are an indicator species for water pollution from > septic systems? > > And, I do not appreciate anybody who tells me they have to work and cannot > get out like I do. I have slowed down so much that I cannot keep up with > my work, let alone my blabbing e-mails. > > Frank Enders, Halifax, NC. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >