mostardi@ux1.lbl.gov (David Mostardi) (09/14/89)
Scene of the sighting: residential Berkeley, CA The field marks: a snow white sparrow, except for the lightest touch of yellow on the sides. Black eyes, flesh colored feet and bill. Notched tail. My guess is that this is probably an escaped exotic, since I can't find *any* snow-white passerine in my No. Amer. field guides. It's not an albino, since it has a black eye. Guesses, anyone?
mjm@oliven.olivetti.com (Michael Mammoser) (09/19/89)
In article <3791@helios.ee.lbl.gov>, mostardi@ux1.lbl.gov (David Mostardi) writes: > > My guess is that this is probably an escaped exotic, since > I can't find *any* snow-white passerine in my No. Amer. field > guides. It's not an albino, since it has a black eye. I wouldn't so quickly rule out an albino. Albinism occurs in varying degrees from patches of white feathers scattered around the body to a totally white bird with the corresponding lack of pigment in the eyes and skin. Actually, the total albino is the rarest form of albinism; and the chances that you would see an incomplete or partial albino are much greater. This bird may very well be an incomplete albino; that is, a bird with totally white plumage but still retaining pigment in the eyes. Mike P.S. I haven't a clue as to what it might be.
john@nmtsun.nmt.edu (John Shipman) (09/20/89)
Michael Mammoser (mjm@oliven.olivetti.com) writes: +--- | I wouldn't so quickly rule out an albino. Albinism occurs | in varying degrees from patches of white feathers scattered | around the body to a totally white bird with the corresponding | lack of pigment in the eyes and skin. +--- Indeed, I've seen several albinos in my 15 years of serious birdwatching. For example, a Sooty Shearwater I saw on a Monterey Bay pelagic trip had big white blotches all over its body, as if someone had dabbed it with a white shoe polish applicator. A Northern Mockingbird I saw in New Mexico had an all-white tail but was otherwise normal. And a gull I saw at the flood basin in Palo Alto was all-white; the consensus of the authorities that saw my picture was that it was an albino California Gull. Be careful, though! The redoubtable G. Victor Morejohn was collecting shearwater specimens on Monterey Bay a few years back and got one that had an all-white head. He figured it was an albino something-or-other and duly sent it off to Roxie Laybourne at the Smithsonian (the same woman who gets all the criminal cases involving feather identification) and in a few months he got back word that he had the first documented North American record of Streaked Shearwater. (-: It helps to have a complete collection of :-) (-: all the field guides in the entire world. :-) While we're on the subject of nasty field identification problems, how about hybrids? The Christmas Bird Counts from the northern Pacific coast in the last few years often list more Glaucous-winged x Western Gulls than either of the unhybridized species. How are they calling this form?
mjm@oliven.olivetti.com (Michael Mammoser) (09/21/89)
In article <3192@nmtsun.nmt.edu>, john@nmtsun.nmt.edu (John Shipman) writes: > > While we're on the subject of nasty field identification > problems, how about hybrids? The Christmas Bird Counts > from the northern Pacific coast in the last few years > often list more Glaucous-winged x Western Gulls than > either of the unhybridized species. How are they > calling this form? I assume that you mean "how are they identifying this form". I, personally, haven't had the guts to claim that I've seen one, but it seems that the ID is based on the gray mantle/wing and the dark primary tips being intermediate in color between the two. The two birds should be quite similar in other field marks (i.e. size, bill shape, leg color, etc.). You then have a bird with a mantle/wing color a darker shade of gray than a Glaucous-Winged but lighter than a Western, and the primary tips a dark brown or dark gray but not quite the black of a Western. As far as identifying a juvenile; I don't know. I would guess that the increase in the reported numbers is probably due to an increased ability of observers to identify this hybrid. Speaking of hybrids, I've seen a couple of interesting ones in recent years. A few years ago I was at the Palo Alto Baylands around the beginning of the year and saw what I'm sure was a Northern Shoveler x Blue-Winged Teal hybrid. The bird had a bright, distinct white crescent in front of the eye (typical of BWT). This was not the fuzzy, indistinct crescent seen in juvenile and eclipse male Northern Shovelers. It had a dark brown crown separated from the rest of the head by a sharp line of contrast (typical of BWT). The rest of the head and neck was an iridescent green (typical of NS). It had a pale yellow eye (typical of NS). The breast was densely marked with small spots on a light brown or tan ground color (typical of BWT). The spotting continued down the sides, with a small patch of chevron-like marks on the upper-rear flank (typical of BWT), but the ground color had changed to a dark orange (typical of NS). The bill was long and spatulate, and the bird was feeding at the edge of the water by sieving water through its bill (typical of NS). This was easily the most unusual duck I have seen. Another hybrid that has been around the Baylands and Charleston Slough for a couple of years, and seen by a number of people, is a Snowy Egret x Little Blue Heron. The bird looks a lot like a Snowy Egret except that the upperparts are marked with gray blotches and the legs are a more uniformly colored gray or green. When first seen a few years ago, the bird was identified as a juvenile Little Blue Heron. This is understandable, considering that Little Blues are seen sporadically and have recently been confirmed as breeders in the South Bay. The ID was further compounded by the fact that the bird had yellow lores and the first edition of the National Geographic Society Field Guide to the Birds of North America shows juvenile Little Blues to have yellow lores. Someone, who evidently had experience with Little Blues, indicated that they have grayish lores in all plumages (this is shown correctly in the second edition of the NGS field guide). This field mark has been used to justify the hybrid status of the bird (along with the fact that the bird's plumage hasn't changed from its blotchy gray on white in a number of years). Any other interesting hybrids out there? Mike
john@nmtsun.nmt.edu (John Shipman) (09/22/89)
Michael Mammoser (mjm@oliven.olivetti.com) writes: >...Any other interesting hybrids out there? Thanks for the descriptions of Glaucous-winged x Western gulls, Blue-winged Teal x Northern Shoveler and Snowy Egret x Little Blue Heron. Plumages like this can make strong men weep. In the late 70's I photographed a duck at the Palo Alto Duck Pond that was probably an American x Eurasian Wigeon, according to local expert Ted Chandik. The head was like EW, rufous with a yellow crown stripe, while the body was like AW, with rusty flanks. Another screwball duck I photographed was at Bosque del Apache NWR in central New Mexico in late March 1988. This bird was clearly a male Blue-winged x Cinnamon Teal. The body ground color was a rusty color, much darker than BWT and only a shade lighter than a CT, but covered with small round dark spots all over like BWT. The bird had the BWT's strong white crescent between the bill and eye, and the head above the eye had a strong bluish tinge, but the rest of the head was cinnamon-colored. This business of Glaucous-winged x Western gulls really bothers me. I have a database of all the Christmas Bird Counts from 61-62 through 87-88, and when I look at the occurrence of this form, it looks like it's spreading rapidly on the west coast. In the 69th CBC there are no records of this hybrid. In the 79th, there are records in two counts in Washington (Grays Harbor and Olympia), one in Oregon (Eugene), and none in California. The 87th, however, has records all over northern California (including the Bay Area and Monterey area) and even two in Los Angeles. But I'm afraid it's not the BIRD that spreading, just information on how to identify it! This is one of the big problems in interpreting field data, and in my line of work it bites me all the time. -- John Shipman/Zoological Data Processing/Socorro, New Mexico USENET: ucbvax!unmvax!nmtsun!john CSNET: john@nmtsun.nmt.edu ``A lesson from past over-machined societies...the devices themselves condition the users to employ each other the way they employ machines.'' --Frank Herbert
mjm@oliven.olivetti.com (Michael Mammoser) (09/23/89)
In article <3215@nmtsun.nmt.edu>, john@nmtsun.nmt.edu (John Shipman) writes: > > In the late 70's I photographed a duck at the Palo Alto Duck > Pond that was probably an American x Eurasian Wigeon, > according to local expert Ted Chandik. The head was like > EW, rufous with a yellow crown stripe, while the body was > like AW, with rusty flanks. I saw a duck at Arrowhead Marsh which I thought was a hybrid between American and Eurasian Wigeon. It had the green eye patch like an American Wigeon with a grayish crown, but the head below the eye patch was reddish brown and it had a yellow forehead stripe. I remember seeing three Eurasian Wigeons on Adobe Creek, next to Charleston Slough, that ranged nicely from extreme juvenal plumage to near-adult. The youngest one had a very indistinct forehead stripe with a darker brown head color. The sides were uniformly colored a reddish brown. At this point the back was still brown. The near-adult bird was colored exactly like an adult except for a few spots of rust on the upper flanks. The bird that was in-between was also like an adult except for more rust color on the sides and the back was still blotchy with some brown feathers. These three birds, all seen on the same day, at the same place, within about an hour's time, were an excellent demonstration of the juvenile molt sequence. Mike
dmark@joey.cs.buffalo.edu (David Mark) (09/23/89)
In article <3192@nmtsun.nmt.edu> john@nmtsun.nmt.edu (John Shipman) writes: > >While we're on the subject of nasty field identification >problems, how about hybrids? The Christmas Bird Counts >from the northern Pacific coast in the last few years >often list more Glaucous-winged x Western Gulls than >either of the unhybridized species. How are they >calling this form? A phenotypically pure glaucescens has no black whatsoever in the wings. Essentially all of the big gulls breeding on the British Columbia coast on the "inside" of Vancouver Island, and north of Vancouver Island, are like this. But, on the "outside" of V.I., a small proportion have black or very dark areas on the upper side of the primaries. I went out to Cleland Island off Tofino with Mike Sheppard, then of the Provincial Museum, to band gulls. There were 3 phenotypically-pure "occidentalis" types among the several thousand "glaucescens", two "occidentalis" paired to eachother and not breedings, the other paired to a glaucescens. I recall that I estimated about 1-2 % of the gulls there appeared to be hybrids. Around Westport, Washington, in summer, it is very hard to find "pure" occidentalis *OR* glaucescens, with most birds being intermediate. Frankly, I don't understand why they have not been lumped. It is obvious that the GULLS don't care about the difference. Hoffman, Wiens, and Scott (Auk 95:441-456, 1978) studied the hybridization along the Washington Coast, and found that hybrid pairs had higher breeding success than pure tryue-to-type pairs. In color, adult "gloccidentalis" birds resemble thayeri. Primaries are dark above but not below, dark iris. But the 'jizz' is quite different, with thayeri adults being rather 'delicate', looking almost like large Mew gulls, or at least like Californias, whereas 'gloccidentalis' are big bulky birds with large long bills, flatter heads, etc. Another hybrid that occurs around Vancouver BC in winter is HerringXGlaucous-w. These also have a similar phenotype to the above hybrid and to thayeri. They come from Cook Inlet area, when interior Herring types spead from dump to dump out to the coast. Once, I saw an adult, color-banded gull near Vancouver, which had this dark-above, light-below pattern on the primaries. I sent in the color pattern to the banding office and it turned out to have been banded as a chick in the Cook Inlet area. Obviously, observers in southern California or the southwest, who perhaps are unfamiliar with thayeri, should be cautious in identifying adult gulls with the primary pattern mentioned above as Thayer's Gulls. David Mark dmark@cs.buffalo.edu
dmark@joey.cs.buffalo.edu (David Mark) (09/23/89)
In article <48269@oliveb.olivetti.com> mjm@oliven.olivetti.com (Michael Mammoser) writes: > > Speaking of hybrids, I've seen a couple of interesting ones >in recent years. A few years ago I was at the Palo Alto Baylands around >the beginning of the year and saw what I'm sure was a Northern Shoveler >x Blue-Winged Teal hybrid. The bird had a bright, distinct white crescent >in front of the eye (typical of BWT). [remainder of excellent description deleted] am looking at a picture of the New Zealand race of the Australalian Shoveler, Anas rhynchotis variegata, and except perhaps for the crown, your description seems to fit it perfectly. An escaped New Zealand Shoveller in the Bay area would be very unlikely, but so would be a hybrid. But then again, hybrids are much more common in captivity, so maybe it was an escaped hybrid... David Mark dmark@cs.buffalo.edu
dmark@joey.cs.buffalo.edu (David Mark) (09/23/89)
In article <3215@nmtsun.nmt.edu> john@nmtsun.nmt.edu (John Shipman) writes: > >This business of Glaucous-winged x Western gulls really >bothers me. I have a database of all the Christmas Bird >Counts from 61-62 through 87-88, and when I look at the >occurrence of this form, it looks like it's spreading >rapidly on the west coast. In the 69th CBC there are no >records of this hybrid. In the 79th, there are records in >two counts in Washington (Grays Harbor and Olympia), one in >Oregon (Eugene), and none in California. The 87th, however, >has records all over northern California (including the Bay >Area and Monterey area) and even two in Los Angeles. > >But I'm afraid it's not the BIRD that spreading, just >information on how to identify it! This is one of the >big problems in interpreting field data, and in my line >of work it bites me all the time. John, this diffusion of information about a 'new' form, rather than diffusion of the form itself, was exactly the point in my 1981 article: "Thayer's Gulls from western Christmas bird counts: a cautionary note." which appeared in American Birds, 35, 898-900. Thayer's Gull was split from Herring in 1973. The percentage of Thayer's Gull among Thayer's + Herring in the west coast states and province was total B.C. 1973 5.2% 27.2% 1974 9.5% 21.9% 1975 15.3% 57.5% 1976 20.8% 70.3% 1977 20.3% 82.0% 1978 11.9% 34.6% If the 1976-77 data represent some sort of equilibrium, then it took 3-4 years for knowledge of a "new species" to spread through the birding community. And I bet there are positive feedbacks, with ambiguous cases going by default into the more common form, rather than being left as "gull sp.". Obviously, most amateur birders (including myself), are species-centric, and news of a hybrid form would spread much more slowly and irregularly, I imagine. David Mark dmark@cs.buffalo.edu
mjm@oliven.olivetti.com (Michael Mammoser) (09/28/89)
In article <10774@eerie.acsu.Buffalo.EDU>, dmark@joey.cs.buffalo.edu (David Mark) writes: > > am looking at a picture of the New Zealand race of the Australalian > Shoveler, Anas rhynchotis variegata, and except perhaps for the crown, your > description seems to fit it perfectly. An escaped New Zealand Shoveller > in the Bay area would be very unlikely, but so would be a hybrid. But then > again, hybrids are much more common in captivity, so maybe it was an > escaped hybrid... You are correct about the similarity between New Zealand Shoveler and a Northern Shoveler x Blue-Winged Teal. An excerpt from Waterfowl: an ID Guide reads: "Occasional wild hybrids between Northern Shoveler and Blue-Winged or Cinnamon Teals bear a remarkable resemblance to Australasian Shovelers, but are smaller and of course likely to be met with only in North America." However, there were some basic differences that led me to believe that this bird was a hybrid. The head color of the New Zealand Shoveler is a slate-gray, whereas my bird had the green head of a typical Northern Shoveler. The marks along the breast and sides of New Zealand Shoveler are small chevron-like marks, whereas my bird had small roundish spots like a Blue-Winged Teal. The ground color of the sides and breast of the New Zealand Shoveler is an orange/brown that continues from the sides onto the lower breast and fades to whitish on the upper breast, whereas my bird had a breast that was uniformly colored light brown/tan that suddenly changed to orange/brown on the sides at the point where it normally changes to this color on a typical Northern Shoveler. It is certainly helpful to have an ID guide to world birds of a particular family when trying to identify an unusual looking species. Based on the field mark differences stated above, I still believe that the bird I saw was a hybrid, although I can't say whether it was wild or an escaped captive. Mike