Sunday, December 20, 2009

more than chickadees on the CBC

Having your count area include Lake Michigan waterfront always makes for a more entertaining day.

The following is a photographic rendition of what the purple sandipiper that flew past us and landed for less than a minute each on Tiscornia Beach, and the North and South Pier, might have looked like if it had rested on say, an algae covered rock, instead of a concrete pier, and sat for an hour, instead of running around constantly, in nice morning light, rather than heavy overcast. Tim managed a few IDable frames with the SLR, but my digiscoping efforts were futile. The pic is from New Buffalo about 3 years ago.
Next is a Ross's type goose that was in the rivermouth. It would appear to be the same bird as Tim found at LMC about a week ago.

The bird's small size (check out the HEGU behind it), short bill, bluish bill base, and utter lack of a grin patch are apparent. The bird's entirely white plumage in winter (per Pyle II) indicate that the bird is an adult. Is it a Ross's goose though? If so, based on the Audubon Society homepage, it would be the fourth for a Michigan CBC in the last 50 years.
The bill is accepted as the best way to discriminate between Ross's, Snow, and hybrid geese. In the positive column, I think it has as little black on the bill as any Ross's-type I've ever seen in Michigan (admittedly the only place I've seen Ross's geese). On the other hand I've seen Michigan birds that have a lot more actual wartiness to the bill base, though this increases gradually as the birds age. Pyle II gives the culmen (upper bill edge) length of Ross's goose as 35-47mm (41mm on average). Olsen and Larsson give the bill length of Herring gull to be 44-62mm (53mm avg). When I take those measurements on the top photo, the goose's culmen is about 80% of the length of the Herring Gull's bill giving the goose's culmen an estimate of 35-50mm (~43mm), somewhat closer to the measurement Pyle gives for pure Ross's (41mm) than for hybrids (47mm). However, even if those rough measurements could be reliable, other sources (Roberson, 1993 and Trauger et al, 1971) indicate that F1 hybrids between Ross's and the smaller (Lesser) Snow Goose subspecies tend to be small birds, many of whose measurements overlap those of Ross's, and are outside the limits of most Lesser Snow Geese. The Trauger paper is an interesting one, accessible through SORA reporting measurements made on 24 "intermediate" white geese and comparing them with about 150 Ross's and about 130 Snow Geese. Culmen length, tarsus (leg) length, total body length, and flattened wing length in adults all overlapped significantly between (presumed) F1 hybrids and presumed pure Ross's geese and were outside the ranges of Lesser Snow Goose. He found weight to be more intermediate. Sibley describes hybrids as intermediate in size. Pyle's average culmen lengths for Ross's, Snow, and hybrid geese are generally within a millimeter of what Trauger came up with but calculated 95% confidence intervals where the culmen length of hybrids overlapped both Lesser Snow and Ross's.
Which brings us to the all-important, unmeasureable, and subject-to-position-and-angle bill interface. Pyle describes this as "malar feathering extending distally to the forehead feathers," in Snow and "malar feathering not extending distally to the forehead feathers in Ross's." Now we get to parse words Bill Clinton style and try to define "malar." Pyle claims to follow Sibley's definition of "malar" even though Sibley in one of the articles referenced by Pyle (Sibley, 2001) explains why Pyle doesn't follow Sibley's definition of "malar." Pyle defines "malar" as "pertaining to the feather group at the posterior end of the gape and extending back to the neck" whereas Sibley defines it as "originating at the base of the lower mandible below the gape and extending back along the sides of the lower jaw." If Pyle follows Sibley's definition then neither bird has malar feathers extending distally to the forehead, for a photo, here's one I posted in March of a bunch of Snows with a Ross's-type. The forehead feathers are more distal to the malar in every bird including the Snows. Pyle must mean the cheek feathering extends forward in Snow and not in Ross's. Here's where a picture is worth a thousand words. Unfortunately Sibley's picture of a hybrid is of a small-billed bird (admittedly with a much more prominent grinpatch than the absent one on this bird) with the upper base of the bill hooking back a little towards the eye, essentially what this bird's does. On the other hand, so do a decent number of the birds on Robert Royse's page photographed in New Mexico.

Interestingly, Trauger concluded in 1971 that intermediate birds comprised about 5% of the Ross's population and felt that it was possible that "pure" Ross's may in the future cease to exist as the population becomes swamped with Lesser Snow Goose genes. As an example, he reported data suggesting that Black Ducks were outnumbered by Mallards by about 6:1 in North America, whereas Ross's goose was outnumbered by about 27:1 making hybrid pairings even more likely. I'm not sure that these Arctic geese aren't any different from the Arctic gulls; who knows where Kumlien's stops and Thayers begins in many individuals, the same may be becoming true for these.
At least in a week they won't need to be reviewed in Michigan any more, right? Right? Hmmmm...
Sibley, DA. "What is the Malar?" Birding, 32: 448-451. Oct 2000.
Trauger DL, A Dzubin, and JP Ryder. "White Geese Intermediate between Ross's Geese and Lesser Snow Geese." Auk, 88: 856-875. Oct 1971

Thursday, December 17, 2009

A swing and a miss

Success rates on chasing birds are always higher if you can go the day a bird is found. I was unable to locate the Trumpeter Swans that Tim found yesterday while I was at work in a decidedly half-hearted effort this morning.

Here's some file photos of Trumpeters from Washtenaw where they breed (bred?) in small numbers when I lived there. Those of traceable origin there had been released in Ohio (where they're not yet countable - more later) but are countable in Michigan since the re-introduction of birds (mainly in the UP) has been termed a "success".You can compare and contrast the pattern of the feathering of the side of the bill and the top of the bill between Trumpeter and Tundra between these two pics (it'd be better if my image program could flip images). As shown in Sibley, Trumpeter has pointed feathering extending down from the forehead but a relatively straight cheek. Tundra on the other hand has a relatively straight forehead but a noted bend to the cheek feathering giving a more vertical lower bill base...
Notice though, that the pattern doesn't hold as well for young birds. The young tundra on the right has a pointed forehead...
As far as birds to miss, I certainly could have missed a worse bird (though perhaps as the water contracts down I'll still find them). From a listing perspective, different state committees have had a lot of trouble deciding what to do with them. Adam Byrne summarized the Michigan perspective in the 2001 proceedings of the committee supporting its acceptance onto the Michigan list. The rationale makes sense (though applies to the UP population better than the ones I saw more frequently around Ann Arbor which I guess are more or less "grand-fathered" in since I don't think they would meet the ABA criteria reviewed by Adam by themselves). Who knows the origin of the birds on Paw Paw Lake. Adam does note a cluster of Southwest LP counties with breeding Trumpeters. I don't claim to know that much about the breeding birds of surrounding counties over here; the only pair I know of is one county north at Wolf Lake Fish Hatchery. I couldn't come up with the Breeding Bird Atlas II results on the web and don't own the first Atlas book. The Seney birds in the UP apparently stay up there in a river mouth that stays open in winter but I don't know what the other birds in SW Michigan do. I remember Trumpeters on the un-frozen Huron River in Ann Arbor in Michigan in February so I doubt they go far in general (though some birds banded from various midwestern programs have been seen/recovered along the Gulf coast in winter).
It seems that the historical evidence suggests that Trumpeters were present in Michigan "originally," which is generally accepted as the eastern limit to their breeding range; most feel that "re"-introductions east of Michigan are in fact introductions. I suppose in some respects there's not a lot of difference between counting a Trumpeter Swan versus a (fast-disappearing) Ring-necked Pheasant or (nearly extirpated (except for released?)) Bobwhite in Berrien whose current trajectories suggest that both will probably be gone here in 20 years barring further releases. Still, I hope Trumpeter Swan (or Monk Parakeet) isn't my 300th bird for Berrien, a number I'll probably hit by next summer.

In case there's anyone still reading who wants to read even more about Trumpeter Swans, the thread on the Bird Record Committee list on will provide a good jumping-off point...

Tuesday, December 8, 2009

A few more grebe notes

Both the Western and the Red-necked Grebe were fairly cooperative today from the pier at Tiscornia (a Purple Sandpiper flew back and forth for a few minutes but didn't land).

A look at the lores (and a breast wound)...

The bird spent a decent amount of time preening, focusing especially on the spot on the upper breast/lower neck where a little exposed skin was present. This provided a chance to record the dark on the upper and lower mandibles

Here's the probable source of the neck wound (though there's sometimes a few loons around too)...
Tim saw the two birds interacting earlier during the week. Apparently the Red-necked was fairly aggressive towards a couple mallards that swam by too. I timed the Red-necked as it dove a few times. I recorded dives of about 30, 30, 32, 40, and 50 seconds. There was also one time when it dove and the coast guard boat roared out from between the piers and I never saw it surface. Once it came up with an ugly-looking bull-headed invasive Goby fish; if the fish was big enough it would take the bird several seconds to swallow it and we could watch the bulge slowly going down the neck. After these episodes it would swim farther out and rest a while before returning to fish. Both Western dives that I timed were about 30 seconds, though Tim's impression was that it usually stayed down longer; an N of two is clearly insufficient in any case.
Stay tuned to Tim's pics (linked on the side of the blog) for flyby Purple Sand pics down the line.

Tuesday, December 1, 2009

Arctic Tern

An Arctic Tern (found by Kip Miller) has been spending the last few days at 3 Oaks. It was bright enough today that digi-scoping was sort of effective, though I'm not great at digi-scoping flying birds (admittedly however, that's why God created the SLR).

The main ID feature for a first cycle bird are the bright white secondaries; a Common Tern has darker gray there. The cap is a little more extensive (almost giving a Franklin's gull like facial look), the bill a little thinner, and the black edging on the primaries much less extensive than a Common Tern.
A couple of my series of shots suggests a gap in the secondaries, I'm not convinced this isn't just from feather mis-arrangement however. Kaufman Advanced Birding states that primary moult in Arctic terns occurs exclusively on the winter grounds; nothing is said with regards to the secondaries.

Here's the bird perched; the short legs are unfortunately hidden. Tim and I discovered today that one of the structures it perches up on is easily visible from Schwark Rd when we were driving away and saw it from the truck.
Note the difference in the primaries' gray shade in the above pic when in oblique sunlight and with them shaded below. Apparently tern primaries have a powdery bloom which slowly wears off causing the feathers to darken as they age.

As the bird dip-dives downward orangey feet were revealed. The bill has essentially lost the color on the lower mandible which Sibley shows in a fresh juvenile. However, a reddish color is apparent especially at the lower base when the bird has its bill ajar while preening.
I spent a little time on the searchable database, which revealed 18 records. A definite pattern exists, all 19 records (counting this one) come from corner counties of the state, Chippewa (8 records), Berrien (5 records counting this bird), Monroe (4 records), and Bay (2 records).
There are three May records; all that were aged in the summaries were adults. There are eight summer records from June, or more commonly, July. There are no UP summer records, although this likely reflects the migration survey periods and observer coverage. Conversely, all of the Monroe birds are from the summer. The summer birds are the most heterogeneous in terms of age. Some were in adult alternate plumage, presumably failed breeders. Some were in basic plumage, and at least a couple were considered subadult birds (most terns (and a lot of sandpipers) spend their first full summer on the "wintering" grounds and so don't come north to breed until they're at least 2 full years old). The fall records are almost exclusively first cycle birds no longer in full juvenile plumage. There are 5 Chippewa records from September or October, but no fall birds have been found in the LP before November. No fall birds have been found in Monroe Co at all (perhaps a bird for the radar screen of hawkwatchers?).
Clearly terns in November need to be scrutinized just like a myarchid flycatcher where Ash-throated would probably be more likely that Great-crested. That being said, the Berrien Field Notes compiled by Jon and edited by Kip, report county late dates for Common Tern of Nov 10 in 2001, Nov 15 in 2006; we had one Nov 10 this year (assuming that all of these late birds were Common, in the other years the late date is mid-late October).
At any rate, I'm looking forward to continuing to study the terns when they return next year. One thing I definitely want to check is how Common Terns hold their tails. This bird has always struck me as holding its tail somewhat creased upwards in the fashion of a grackle or the tail fins on an F-117 stealth fighter. I'll be curious to see if Common's hold their tail that way or not, and if I get to Maine as planned next summer for a family reunion check it on more Arctics.
[note: post edited 12/7/09 thanks to a clarification from Adam Byrne regarding the number of accepted records]