Documents • Iowa State University • Avian Archives of Iowa Online

Title	Genres	Topics	Date (Start)	Date (End)	Type	Description	Creator/Author	Birds	Locations	Locality	Habitat	Remarks

Records committee review for rare bird sighting of Thayer's Gull at Red Rock Reservoir, 1986	Administrative records Field notes	Bird watching Ornithology Ornithology--Societies, etc	1986-12-13	1993-09-07	Rare birds documentation form	Records Committee review for two to five Thayer's Gulls at Red Rock Reservoir in Marion County, IA on December 13, 1986. Includes a record review document with votes, a summary of the review, and a documentation form submitted to the committee.	Dinsmore, Stephen J.	Thayer's Gull	Lake Red Rock	Red Rock Res., Marion Co.-below dam and near the Hwy 14 bridge	resting on sand bar below dam and feeding near open water on main lake	The documentation form by Steve Dinsmore is the only one submitted and forms the basis of this record. Other observers include Mark Proescholdt, Tom Kent, and Tom Staudt. \| Elimination of similar species: The dark tail band and fairly dark body coloration should eliminate Iceland Gull. The smaller bill, rounder head, smaller size, more even body coloration, and pale undersides of the wings eliminates first-winter Herring Gull. \| The original documentation form event occurred around 10:00:00.	Iowa Ornithologists' Union \| MS 166	11	3
Records Committee review for rare bird sighting of Thayer's Gull at Saylorville Dam, 1988	Administrative records Field notes	Bird watching Ornithology Ornithology--Societies, etc	1988-12-30	1993-08-04	Rare birds documentation form	Records Committee review for two Thayer's Gulls at Saylorville Dam in Polk County, IA on December 30, 1988. Includes a record review document with votes and a documentation form submitted to the committee.	Johnson, Ann	Thayer's Gull	Saylorville Dam	Saylorville Lake, Polk Co., IA	dam on Des Moines River forming reservoir	The documentation form by Ann Johnson is the only one submitted and forms the basis of this record. \| Elimination of similar species: The primary identification was done through the size and shape of the head. Other similar gulls do not share this "dove head." The adult was confirmed by the silvery underwings, not shared by similarly gray-mantled gulls, and the first year bird was confirmed by the uniformity of its body color. \| The original documentation form event lasted from 15:40:00/15:55:00.	Iowa Ornithologists' Union \| MS 166	11	3
Records Committee review for rare bird sighting of Thayer's Gull at Red Rock Dam, 1988	Administrative records Field notes	Bird watching Ornithology Ornithology--Societies, etc	1988-12-13	1993-08-04	Rare birds documentation form	Records Committee review for a Thayer's Gull at Red Rock Dam in Marion County, IA on December 13, 1988. Includes a record review document with votes and a documentation form submitted to the committee.	Johnson, Ann	Thayer's Gull	Red Rock Dam	below dam - Lake Red Rock, Marion Co, IA	dam on Des Moines River forming reservoir; open river with islands	The documentation form by Ann Johnson is the only one submitted and forms the basis of this record. \| Elimination of similar species: Ring-billed eliminated by size and leg color. Herring eliminated by head shape and eye color. Iceland eliminated by eye color, mantle color, and size and shape of head. \| The original documentation form event lasted from 15:01:00/15:03:00.	Iowa Ornithologists' Union \| MS 166	11	3
Records Committee review for rare bird sighting of Thayer's Gull north of Jester Park at Saylorville Reservoir, 1988	Administrative records Field notes	Bird watching Ornithology Ornithology--Societies, etc	1988-11-30	1993-08-04	Rare birds documentation form	Records Committee review for one to three Thayer's Gulls north of Jester Park at Saylorville Reservoir in Polk County, IA on November 30, 1988. Includes a record review document with votes and a documentation form submitted to the committee.	Dinsmore, Stephen J.	Thayer's Gull	Jester Park	Saylorville Reservoir, Polk Co.-north of Jester Park	feeding in river channel with thousands of other gulls	The documentation form by Steve Dinsmore is the only one submitted and forms the basis of this record. Other observers include many unidentified other observers. \| Elimination of similar species: The bill and leg color and size eliminates all gulls except Herring, Thayer's, and Iceland gulls. The uniform dark color of the wings, lack of a lighter "window" on the inner primaries, and the silvery color of the underside of the flight feathers eliminates 1st-winter Herring and Iceland gulls. \| The original documentation form event lasted from 13:38:00/14:55:00 on November 30, 1988.	Iowa Ornithologists' Union \| MS 166	11	3
Records Committee review for rare bird sighting of Thayer's Gull north of Jester Park at Saylorville Reservoir, 1988	Administrative records Field notes	Bird watching Ornithology Ornithology--Societies, etc	1988-11-30	1993-08-04	Rare birds documentation form	Records Committee review for a Thayer's Gull north of Jester Park at Saylorville Reservoir in Polk County, IA on November 30, 1988. Includes a record review document with votes and a documentation form submitted to the committee.	Dinsmore, Stephen J.	Thayer's Gull	Jester Park	Saylorville Reservoir, Polk Co.-north of Jester Park	feeding in river channel with thousands of other gulls	The documentation form by Steve Dinsmore is the only one submitted and forms the basis of this record. \| Elimination of similar species: The bill and leg color and size eliminates all gulls except Herring, Thayer's, and Iceland gulls. The uniform dark color of the wings, lack of a lighter "window" on the inner primaries, and the silvery color of the underside of the flight feathers eliminates 1st-winter Herring and Iceland gulls. \| The original documentation form event lasted from 13:38:00/14:55:00.	Iowa Ornithologists' Union \| MS 166	11	3
Records Committee review for rare bird sighting of Thayer's Gull at Lock and Dam 15 in Davenport, 1988	Administrative records Field notes	Bird watching Ornithology Ornithology--Societies, etc	1988-01-01	1993-08-04	Rare birds documentation form	Records Committee review for a Thayer's Gull at Lock and Dam 15 in Davenport in Scott County, IA on January 1, 1988. Includes a record review document with votes and a documentation form submitted to the committee.	Kent, Thomas H. (Thomas Hugh), 1934-	Thayer's Gull	Lock and Dam 15	Lock + Dam 15, Davenport, Scott Co, IA	Mississippi R.	The documentation form by Thomas H. Kent is the only one submitted and forms the basis of this record. Other observers include Francis Moore and Dick Kraemer. \| Elimination of similar species: [...] There were many first year Herrings that were darker with dark wingtips. We also saw, but not at same time, a larger, slightly lighter gull without tail band that we identified as a first year Glaucous Gull. It was consistently larger than Herring and heavier bodied. Uniform color, white flight feathers from below separate bird from Herring. Size and tail band separate from Glaucous. \| The original documentation form event lasted from 10:15:00/10:45:00.	Iowa Ornithologists' Union \| MS 166	11	3
Records Committee review for rare bird sighting of Thayer's Gull at Saylorville Reservoir Dam, 1987	Administrative records Field notes	Bird watching Ornithology Ornithology--Societies, etc	1987-12-02	1993-09-07	Rare birds documentation form	Records Committee review for two or more Thayer's Gulls at Saylorville Reservoir Dam in Polk County, IA on December 2, 1987. Includes a record review document with votes and five documentation forms submitted to the committee.	Dinsmore, Stephen J.	Thayer's Gull	Saylorville Dam	Saylorville Reservoir, Polk Co.	sitting on ice with other gulls	The documentation form by Steve Dinsmore forms the basis of this record. Other documentation forms by Francis L. Moore, Steve Dinsmore, and Mark Proescholdt were submitted. Other observers include Andy Fix, Beth Proescholdt, Eugene Armstrong, Eloise Armstrong, Bob Cecil, Bery Engebretsen, Jim Sinclair, and many unidentified observers. \| Elimination of similar species: The overall dark color of the bird and the lack of paler wingtips eliminates first-winter Iceland Gull. The translucent flight feathers, uniform body color, lack of a "window" on the upperwing, smaller, thinner bill, rounder head, dark smudge around the eye, and smaller size eliminates first-winter Herring Gull. The uniform body color, lack of a dark tail band, and translucent flight feathers eliminates first-winter Lesser Black-backed Gull. \| The original documentation form event lasted from 08:00:00/08:05:00.	Iowa Ornithologists' Union \| MS 166	11	3
Records Committee review for rare bird sighting of Thayer's Gull at Red Rock Reservoir, 1987	Administrative records Field notes	Bird watching Ornithology Ornithology--Societies, etc	1987-01-03	1993-09-07	Rare birds documentation form	Records Committee review for a Thayer's Gull at Red Rock Reservoir in Marion County, IA on January 3, 1987. Includes a record review document with votes and a documentation form submitted to the committee.	Kent, Thomas H. (Thomas Hugh), 1934-	Thayer's Gull	Lake Red Rock	Red Rock Res., Marion Co., Iowa	reservoir, partly frozen	The documentation form by Thomas H. Kent is the only one submitted and forms the basis of this record. Other observers include Tom Staudt, Steve Dinsmore, and unidentified other observers. \| Elimination of similar species: The uniform coloration and lack of dark wing tips were the main marks used to separate it from Herring Gull. \| The original documentation form event lasted from approximately 13:30:00/13:45:00.	Iowa Ornithologists' Union \| MS 166	11	3
Records Committee review for rare bird sighting of Thayer's Gull at Lock and Dam 19 in Keokuk, 1987	Administrative records Field notes	Bird watching Ornithology Ornithology--Societies, etc	1987-01-03	1993-09-07	Rare birds documentation form	Records Committee review for a Thayer's Gull at Lock and Dam 19 in Keokuk in Lee County, IA on January 3, 1987. Includes a record review document with votes and two documentation forms submitted to the committee.	Moore, Francis L.	Thayer's Gull	Lock Number 19	Below lock and dam 19, Keokuk, Lee Co., Iowa	Open water below lock and dam 19	The documentation form by Francis L. Moore forms the basis of this record. Another documentation form by Steve Dinsmore was submitted. Another observer includes Robert Cecil. \| Elimination of similar species: Herring Gull has more black in the primaries with a grayer mantle, a larger bill and heavier and bigger head. The under surface of the primaries of a Herring is also darker and has the darkness well into the primaries from the tips. \| The original documentation form event lasted from 10:30:00/10:40:00.	Iowa Ornithologists' Union \| MS 166	11	3
Records Committee review for rare bird sighting of Thayer's Gull at Lock 15 in Davenport, 1986	Administrative records Field notes	Bird watching Ornithology Ornithology--Societies, etc	1986-12-24	1993-09-07	Rare birds documentation form	Records Committee review for a Thayer's Gull at Lock 15 in Davenport in Scott County, IA on December 24, 1986. Includes a record review document with votes and a documentation form submitted to the committee.	Petersen, Peter C.	Thayer's Gull	Lock and Dam 15	Lock 15, Davenport	General: Mississippi River Specific: just below roller dam	The documentation form by Peter C Petersen is the only one submitted and forms the basis of this record. Other observers include Tim Dwyer and Jerry White. \| Elimination of similar species: Herring Gull - wing tips not black on this bird, + its eye was dark. Iceland (Humelius) - wing tips not as pale grey, legs not pale pink. \| The original documentation form event lasted from 10:10:00/10:15:00 on December 24, 1986 and 14:40:00/14:42:00 on December 25, 1986.	Iowa Ornithologists' Union \| MS 166	11	3
Records Committee review for rare bird sighting of Thayer's Gull at Lock and Dam 19, 1986	Administrative records Field notes	Bird watching Ornithology Ornithology--Societies, etc	1986-12-21	1993-09-07	Rare birds documentation form	Records Committee review for a Thayer's Gull at Lock and Dam 19 in Keokuk in Lee County, IA on December 21, 1986. Includes a record review document with votes, a summary of the review, and a documentation form submitted to the committee.	Cecil, Robert I.	Thayer's Gull	Lock Number 19	Lock and Dam 19, Miss. River, Keokuk, Lee Co, Iowa	River rapids.	The documentation form by Robert Cecil is the only one submitted and forms the basis of this record. Another observer includes Doug Reeves. \| Elimination of similar species: First year Herring much more "contrasty"--see above. Kumlien's Iceland Gull...According to Seabirds (Harrison), 1st year Iceland is more pale, tail uniform gray. Overall body coloration is more like 1st year Glaucous--bird I saw was darker than 1st year Glaucous. [...] The important thing about this uniformity that the accompanying first year Herring Gulls had much contrast, showing whitish head, darker wingtips, dark at the tip of the underwings (sometimes), and most obviously, much darker secondaries, creating a dark trailing edge to the wings. Their general color was a darker chocolatey brown. [...] BILL: Pinkish--noticably [sic] smaller that [sic] Herrings. This is pretty subjective, but at about 2/3 of the way across the river at the dam (maybe one third mile) the bill on a Herring can be easily seen through my scope. [...] A very indistinct darkening (wing, upper surface) of the first two or three primaries. The mark had to be looked for to be seen--on the Herring it was much more evident. [...] At some times, the bird showed secondaries that were slightly darker than the rest of the wing. Slightly should be emphasized--at no time was it even close to the darkness of the secondaries of the first year Herring. [...] There was a very slight and indistinct darkening to the first two or three primaries, but this had to be looked for carefully. I have also seen a number of 1st year Herring Gulls that fit this description, but all have a distinct window at base of primaries. \| The original documentation form event occurred at various times during the date range of sightings on the documentation form.	Iowa Ornithologists' Union \| MS 166	11	3
Records Committee review for rare bird sighting of Thayer's Gull at Island View Park at Rathbun Reservoir, 1986	Administrative records Field notes	Bird watching Ornithology Ornithology--Societies, etc	1986-12-20	1993-09-07	Rare birds documentation form	Records Committee review for three Thayer's Gulls at Island View Park at Rathbun Reservoir in Appanoose County, IA on December 20, 1986. Includes a record review document with votes, a summary of the review, and two documentation forms submitted to the committee.	Dinsmore, Stephen J.	Thayer's Gull	Island View Park	Rathbun Reservoir, Appanoose Co. (Island View East and West Areas)	sitting on ice and feeding on open water with other gulls	The documentation form by Steve Dinsmore forms the basis of this record. Another documentation form by Ray Cummins was submitted. Another observer includes Randy Strough. \| Elimination of similar species: The first-year birds were separated from first-year Iceland Gull by the distinct tail band and the darker primaries and from first-year Herring Gull by head shape, bill size, more uniform body color, and the silvery-white underwing. The adult bird was separated from an adult Iceland Gull by size, bill shape, and more black (still not too much, though) in the wingtips and from an adult Herring Gull by head shape, bill size, and paler wingtips. \| The original documentation form event lasted from 10:05:00/10:30:00 and 13:30:00/13:54:00.	Iowa Ornithologists' Union \| MS 166	11	3
Records Committee review for rare bird sighting of Thayer's Gull at Lock and Dam 19, 1986	Administrative records Field notes	Bird watching Ornithology Ornithology--Societies, etc	1986-12-17	1994-11-04	Rare birds documentation form	Records Committee review for a Thayer's Gull at Lock and Dam 19 in Keokuk in Lee County, IA on December 17, 1986. Includes a record review document with votes, summary of review, and a documentation form submitted to the committee.	Cecil, Robert I.	Thayer's Gull	Lock Number 19	Lock and Dam 19, Keokuk, Lee Co., Iowa	River Rapids	The documentation form by Robert Cecil is the only one submitted and forms the basis of this record. Another observer includes Francis L. Moore. \| Elimination of similar species: Herring Gull:Bill size, pattern of wingtips on upper and under surface of wings. Ringbill: size. Kumlien's Iceland: black rather than gray in wintip [sic] (Tom Kent, personal communication). Adult Glaucous has no black in wingtips. \| The original documentation form event occurred at various times on the various dates listed on the documentation form.	Iowa Ornithologists' Union \| MS 166	11	3
Records Committee review for rare bird sighting of California Gull at Cherry Glen Recreation Area at Saylorville Reservoir, 1997	Administrative records Field notes	Bird watching Ornithology Ornithology--Societies, etc	1997-12-09	2000-11-24	Rare birds documentation form	Records Committee review for a California Gull at Cherry Glen Recreation Area at Saylorville Reservoir in Polk County, IA on December 9, 1997. Includes a record review document with votes and a documentation form submitted to the committee.	Overton, Michael D.	California Gull	Cherry Glen Recreation Area	Polk co., Saylorville Reservoir, Cherry Glen Recreation Area	On ice along lakeshore of large manmade lake in mixed hardwood forest agricultural cropland.	The documentation form by Michael D. Overton is the only one submitted and forms the basis of this record. Other observers include Eugene Armstrong and Eloise Armstrong. \| Elimination of similar species: Ring-billed Gull, Herring Gull: Immatures of both species were present so direct comparisons were possible. Bill color, shape, and size reletive [sic] to head. Tail and rump color. Wing color and pattern especially mantle, greater coverts, and secondaries. \| The original documentation form event lasted from 10:20:00/10:55:00.	Iowa Ornithologists' Union \| MS 166	11	1
Records Committee review for rare bird sighting of Thayer's Gull at Red Rock Reservoir, 1986	Administrative records Field notes	Bird watching Ornithology Ornithology--Societies, etc	1986-12-03	1993-09-07	Rare birds documentation form	Records Committee review of two Thayer's Gulls at Red Rock Reservoir in Marion County, IA on December 3, 1986. Includes a record review document with votes and a documentation form submitted to the committee.	Kent, Thomas H. (Thomas Hugh), 1934-	Thayer's Gull	Lake Red Rock	Red Rock Reservoir	reservoir with ice and open water.	The documentation form by Thomas H. Kent is the only one submitted and forms the basis of this record. Other observers include Cal Knight, Bernie Knight, and Jim Fuller. \| Elimination of similar species: Herring Gull --see above. [...] The bird is not any larger than some of the ring-bills--some of the ring-bills are smaller. The larger ring-bills are almost as big as this bird, and it is distinctly smaller than a number of Herring Gulls in the same field. The bill is much smaller and thinner; the head is small. [...] The striking thing about this bird is the size, bill shape and head shape compared to the nearby herrings and very distinct smudge through the eye." \| The original documentation form event lasted from around 09:10:00 for several minutes and 15:55:00 for many minutes.	Iowa Ornithologists' Union \| MS 166	11	3
Records Committee review for rare bird sighting of Thayer's Gull at Cottonwood Recreation Area near Saylorville Dam, 1986	Administrative records Field notes	Bird watching Ornithology Ornithology--Societies, etc	1986-12-03	1993-09-07	Rare birds documentation form	Records Committee review of a Thayer's Gull at Cottonwood Recreation Area near Saylorville Dam in Polk County, IA on December 3, 1986. Includes a record review document with votes and a documentation form submitted to the committee.	Petersen, Peter C.	Thayer's Gull	Cottonwood Recreation Area	Cottonwood Rec. Area below Saylorville Dam. Polk Co		The documentation form by Peter C. Petersen is the only one submitted and forms the basis of this record. Other observers include Beth Proescholdt, Mark Proescholdt, Steve Dinsmore, Gil Sandvick, and unidentified other observers. \| Elimination of similar species: [...] Birds call not distinguishable from Ring-billed Gulls feeding with it. [...] Herring Gull eliminated by lack of sharp contrast between primaries + remainder of mantle + back and whitish undersides of primaries. \| The original documentation form event lasted from 10:02:00/10:03:00.	Iowa Ornithologists' Union \| MS 166	11	3
Records Committee review for rare bird sighting of Thayer's Gull near Saylorville Reservoir Dam and Oak Grove Beach, 1986	Administrative records Field notes	Bird watching Ornithology Ornithology--Societies, etc	1986-11-23	1993-09-07	Rare birds documentation form	Records Committee review for seven or more Thayer's Gulls near Saylorville Reservoir Dam and Oak Grove Beach in Polk County, IA on November 23, 1986. Includes a record review document with votes, a summary of the review, and seven documentation forms submitted to the committee.	Dinsmore, Stephen J.	Thayer's Gull	Saylorville Dam Oak Grove Recreation Area	Saylorville Reservoir, Polk Co.(Oak Grove Beach and near dam)	seen resting on beach and flying over water near dam	The documentation form by Steve Dinsmore forms the basis of this record. Other documentation forms by Steve Dinsmore were submitted. Other observers include Paul Martsching, Bob Myers, Beth Proescholdt, Mark Proescholdt, and many unidentified other observers. \| Elimination of similar species: The darker body plumage and dark tail band eliminate Iceland Gull (Kumlien's form). The smaller size, smaller, more delicate bill, more rounded head, silvery white underwing pattern, more uniform body color, and more uniform upperwing pattern eliminate first winter Herring Gull. \| The original documentation form event occurred at various times.	Iowa Ornithologists' Union \| MS 166	11	3
Records Committee review for rare bird sighting of Thayer's Gull near Oak Grove Beach and Saylorville Reservoir Dam, 1986	Administrative records Field notes	Bird watching Ornithology Ornithology--Societies, etc	1986-11-23	1993-09-07	Rare birds documentation form	Records Committee review for a Thayer's Gull near Oak Grove Beach and Saylorville Reservoir Dam in Polk County, IA on November 23, 1986. Includes a record review document with votes, a summary of the review, and ten documentation forms submitted to the committee.	Dinsmore, Stephen J.	Thayer's Gull	Saylorville Dam Oak Grove Recreation Area	Saylorville Reservoir, Polk Co. (Oak Grove Beach and near dam)	seen resting on beach and flying over water near dam	The documentation form by Steve Dinsmore forms the basis of this record. Other documentation forms by Bob Myers, Mark Proescholdt, Beth Proescholdt, Thomas H. Kent, Jim Fuller, Francis L. Moore, Robert Cecil, and Paul Martsching were submitted. \| Elimination of similar species: The darker body plumage and dark tail band eliminate Iceland Gull (Kumlien's form). The smaller size, smaller, more delicate bill, more rounded head, silvery white underwing pattern, more uniform body color, and more uniform upperwing pattern eliminate first winter Herring Gull. \| The original documentation form event lasted from 10:50:00/11:55:00 and 15:50:00/16:05:00 on November 23, 1986 and 14:50:00/15:35:00 on November 24, 1986.	Iowa Ornithologists' Union \| MS 166	11	3
Records Committee review for rare bird sighting of a Thayer's Gull at Red Rock Reservoir Dam, 1985	Administrative records Clippings (information artifacts) Field notes	Bird watching Ornithology Ornithology--Societies, etc	1985-12-10	1993-09-03	Rare birds documentation form	Records Committee review for a Thayer's Gull at Red Rock Reservoir Dam in Marion County, IA on December 10, 1985. Includes a record review document with votes, an article in Iowa Bird Life, and six documentation forms submitted to the committee.	Bendorf, Carl J.	Thayer's Gull	Red Rock Dam	Red Rock Res. Tailwater		The documentation form by Carl J. Bendorf forms the basis of this record. Other documentation forms by Thomas H. Kent, Francis L. Moore, Bob Myers, Beth Proescholdt and Mark Proescholdt, and Dennis Thompson were submitted. Other observers include Joe Schaufenbuel, Darwin Koenig, Steve Dinsmore, Eugene Armstrong, Eloise Armstrong, and many unidentified observers. \| Elimination of similar species: Thayer's Gull is a difficult bird to identify. In researching this problem, I have found several helpful sources in addition to the standard field guides and I have tried to understand what it takes to know a Thayer's Gull when you see one. Nearly every reference makes it clear that Thayer's cannot be identified on the basis of one or two positive field marks. It takes a combination of characters to come to a conclusion of any certainty. In discussing this particular observation, I will examine each of the fieldmarks and compare and contrast to similar species with liberal reference to the literature, especially Lehman (1980). The most likely similar gulls in this case are 1st winter Herring and 1st winter Iceland (Kumlien's). The Kumlien's form is the darker form of the Iceland Gull and is the form that breeds in the Baffin Island area and winters mainly on the Atlantic coast. Lehman's article deals mainly with Kumlien's. Several similarly sized and possible but unlikely candidates can be eliminated rather quickly. A 1st winter California should not have an all dark bill and would show much darkening in the primaries in flight. Lesser Black-backed Gull could be about the right size, but in flight a 1st winter bird should show darker primary and secondary coverts, more extensively dark primaries, even compared to Herring Gull. A 1st summer Slaty-backed Gull is also light uniform brown with an all dark bill, but it should exhibit extensive darkening in the primaries on the upper wing. A 1st winter Glaucous-winged Gull would be very similar to Thayer's but should be larger, with a larger bill, and less mottling to the body color. Except for the first two, one would probably not consider the likelihood of their occurrence in Iowa to be very great. One hybrid, Glaucous-winged X Western, might be similar but should have a quite heavy bill. [...] Summary: Of the most likely similar species, 1st winter Herring Gull and 1st winter Kumlien's Iceland Gull, each is eliminated by one or more of the features discussed above. The wing pattern is especially damaging to the possibility of Herring, along with the bill shape and size. Iceland is ruled out by the presence of the noticeable tail band and by the darker secondaries on the upper wing. To identify a Thayer's Gull, one must see a combination of field marks. I feel that the bird I saw at Red Rock is consistent on every point.\| The original documentation form event lasted from 14:15:00/14:45:00.	Iowa Ornithologists' Union \| MS 166	11	3
Records Committee review for rare bird sighting of Thayer's Gull at Saylorville Dam, 1981	Administrative records Correspondence Field notes	Bird watching Ornithology Ornithology--Societies, etc	1981-12-10	1993-08-26	Rare birds documentation form	Records Committee review for a Thayer's Gull at Saylorville Dam in Polk County, IA on December 10, 1981 recorded incorrectly as 1982 on the documentation form. Includes a record review document with votes, correspondence and commentary about the sighting, and a documentation form submitted to the committee.	Schaufenbuel, Joseph P.	Thayer's Gull	Saylorville Dam	Above and below Saylorville Dam	Open water, rocky shore and ice covered pond.	The documentation form by Joe Schaufenbuel is the only one submitted and forms the basis of this record. \| Elimination of similar species: [...] Nearly the same size as an immature Herring Gull, but neck seemed thinner, head smaller. Bill was same length as a Herring Gull's but was blunter, not as strongly hooked. [...] The primaries were not nearly as dark as immature (1st year) or 2nd year Herring Gulls and was of a much different color than the black color of that species. Primaries and tail were nearly the same color. [...] In flight this bird could be easily picked out from the immature Herring Gulls at considerable distances. Using 7x35 binoculars the beige color of the upper surface of wings and translucent underwing could be detected as far as three-quarters of a mile. There were also three other birds that resembled this particular bird though they appeared darker on the upperparts. However I was unable to get close observations of these birds. The bird I observed closely and documented had one primary feather missing and aided in tracking the bird from day to day.	Iowa Ornithologists' Union \| MS 166	11	3
Records Committee review for rare bird sighting of Thayer's Gull at Coralville Dam, 1981	Administrative records Correspondence Field notes	Bird watching Ornithology Ornithology--Societies, etc	1981-12-06	1993-08-26	Rare birds documentation form	Records Committee review for a Thayer's Gull at Coralville Dam in Johnson County, IA on December 6, 1981. Includes a record review document with votes, correspondence and commentary about the sighting, field notes, and a documentation form submitted to the committee.	Kent, Thomas H. (Thomas Hugh), 1934-	Thayer's Gull	Coralville Dam	Coralville Res. Dam, Johnson Co., Iowa	Reservoir just above dam on ice	The documentation form by Thomas H. Kent as dictated to Carl Bendorf is the only one submitted and forms the basis of this record. Another observer was Carl Bendorf. \| Elimination of similar species: imm. Herring Gull. The second year Herring has a light bill with black tip and more contrasting black and white pattern to wings and tail. The first year Herring is much darker, has a more bulbous, hooked bill, and lacks the definitewhite [sic] window in flight. \| The original documentation form event lasted from 08:15:00/08:30:00.	Iowa Ornithologists' Union \| MS 166	11	3
Records Committee review for rare bird sighting of Thayer's Gull at Lake Manawa, 1981	Administrative records Correspondence Field notes	Bird watching Ornithology Ornithology--Societies, etc	1981-12-05	1993-08-26	Rare birds documentation form	Records Committee review for a Thayer's Gull at Lake Manawa in Pottawattamie County, IA on December 5, 1981. Includes a record review document with votes, correspondence and commentary about the sighting, and a documentation form submitted to the committee.	Silcock, W. Ross	Thayer's Gull	Lake Manawa	Lake Manawa		The documentation form by W. Ross Silcock is the only one submitted and forms the basis of this record. \| Elimination of similar species: [...] Smaller than adult Herring Gull (winter plumage, red spot end of lower mandible) beside it, legs a little pinker. Larger than Ring-billed Gulls- flock of 14 adjacent. [...] Headmuch [sic] smaller relative to body than in the Herring Gull- also flatter-appearing. [...] 1. Bill was black (or very dark); this , combined with the rather pale underparts relative to the rest of the (also rather pale) plumage tends to rule out a first year Herring Gull. 2. Bill and head size and shape were not as heavy-appearing as in Herring Gull. Direct comparison with adjacent adult Herring Gull was very useful in deciding this. [...] 5. Size and pinker legs than Herring Gull are not sure characters, but lend support to identification as Thayer's Gull.	Iowa Ornithologists' Union \| MS 166	11	3
Records Committee review for rare bird sighting of Thayer's Gull at Coralville Dam, 1981	Administrative records Correspondence Field notes	Bird watching Ornithology Ornithology--Societies, etc	1981-11-08	1993-08-26	Rare birds documentation form	Records Committee review for three Thayer's Gulls at Coralville Dam in Johnson County, IA on November 8, 1981. Includes a record review document with votes, correspondence and commentary about the sighting, summary of the review, and a documentation form submitted to the committee.	Moore, Francis L.	Thayer's Gull	Coralville Dam	Coralville Reservoir	Open wate [sic] near small sandy beach near the Dam area, Johnson County	The documentation form by Francis L. Moore is the only one submitted and forms the basis of this record. Other observers include Russell Hays, Tom Kent, Tom Shires, Tom Staudt, and many unidentified other observers. \| Elimination of similar species: Ring-billed Gull and Herring Gull, see above. The Ring-billed Gulls were seen in direct contrast to these three birds and were definitely much smaller birds. The Herring Gulls (first year birds) that I have seen have more of a contrast between the rump and back and upper wing surfaces and none that I remember showed the whitish trailing edge on the tail. [...] The three birds seen were about the size of Herring Gulls in typical first year plumage. They were obviously large gulls of the genus Larus with a noticeably larger size than the Ring-billed Gulls and one Bonaparte's Gull that were next to the three larger birds. [...] There were no Herring Gulls nearby with which to make a comparison of size and coloration. The bills of all three gulls were black did not seem as heavy or bulky as the bill of a Herring Gull. \| The original documentation form event lasted from 08:10:00/09:30:00.	Iowa Ornithologists' Union \| MS 166	11	3
Records Committee review for rare bird sighting of Thayer's Gull at Coralville Dam, 1981	Administrative records Correspondence Field notes	Bird watching Ornithology Ornithology--Societies, etc	1981-11-07	1993-08-26	Rare birds documentation form	Records Committee review for two Thayer's Gulls at Coralville Dam in Johnson County, IA on November 7, 1981. Includes a record review document with votes, correspondence and commentary about the sighting, and a documentation form submitted to the committee.	Kent, Thomas H. (Thomas Hugh), 1934-	Thayer's Gull	Coralville Dam	Coralville Res. Dam, west overlook, Johnson Co. Iowa	Reservoir, just above dam, in water and on swimming beach	The documentation form by Thomas H. Kent is the only one submitted and forms the basis of this record. Other observers include Carl Bendorf, Mike Newlon, and many unidentified other observers. \| Elimination of similar species: Photographs taken at the first encounter with a Celestron 750 mm lens demonstrate the size difference, the bill and head shape difference, the lighter overall color, and the window in the wing. An adult Herring was in the photo with the Thayer's on 7 Nov and imm Herring were photographed on 10 Nov for comparison. \| The original documentation form event lasted from 09:25:00/09:50:00 and 11:00:00/11:20:00 on November 7, 1981 and 07:30:00/08:30:00 on November 8, 1981.	Iowa Ornithologists' Union \| MS 166	11	3
Records Committee review for rare bird sighting of Thayer's Gull at Lake Manawa, 1981	Administrative records Clippings (information artifacts) Correspondence Field notes	Bird watching Ornithology Ornithology--Societies, etc	1981-03-19	1993-08-26	Rare birds documentation form	Records Committee review for two Thayer's Gulls at Lake Manawa in Pottawattamie County, IA on March 19, 1981. Includes a record review document with votes, correspondence and comments about the sighting, an article in Iowa Bird Life, and four documentation forms submitted to the committee.	Silcock, W. Ross	Thayer's Gull	Lake Manawa	Lake Manawa, Pottawattamie County, Iowa.		The documentation form by Ross Silcock is the earliest and the one that forms the basis of this record. Other documentation forms by Thomas H. Kent, Peter C. Petersen, and Robert K. Myers were submitted later. Other observers include Tom Shires, James Kovanda, Sandra Kovanda, Tanya Bray, Babs Padelford, Loren Padelford, B.J. Rose, and four unidentified other observers. \| Elimination of similar species: The above description separates by direct comparison first-year Thayer's and Herring Gulls, the most similar species present. Thayer's may be confused in first year plumage with Kumlien's form of Iceland Gull, but the Thayer's had primaries slightly darker than the mantle (from above), whereas the opposite occurs in Iceland Gull (Lehman). Lehman also notes that some first-year Western Gulls may show translucent primaries from below in certain light, but these observations took place in excellent light at fairly close range. \| The original documentation form event lasted from approximately 09:30:00/11:00:00.	Iowa Ornithologists' Union \| MS 166	11	3