The Willet breeds from Nova Scotia to California and has two distinct subspecies. The Eastern Willet breeds on the coasts of the Atlantic Ocean and Gulf of Mexico and is known as Tringa semipalmata semipalmata (nominate subspecies). The Western Willet breeds from southern Manitoba to northern California (the Great Plains) and bears the binomial name Tringa semipalmata inornata. Some have argued that these two populations should be considered separate species [Birding - May/June 2006].
The Eastern Willet winters in South American while the Western Willet spends the non-breeding season on both the Pacific and Altantic coasts. The northern extreme of the Western's wintering range on the Atlantic Coast is New Jersey. Willets sighted in Nova Scotia after early September are found to be mostly of the Western subspecies as most of our breeding birds have already left. [All the Birds of Nova Scotia, Ian McLaren]
I found my first Western Willet on October 4, 2014 on the flats in Pubnico Harbour. The following is a distant photo of this bird. If they do ever decide to split this species I'll have another NS lifer up my sleeve.
Western Willets are usually noticeably larger (10% larger) than Easterns but there is overlap due to the size variability in the Westerns. Some male Westerns overlap with Easterns in size. Westerns are lighter and less brown in all plumages and have a heavy chest. Easterns have a shorter, heavier and thicker tipped bill. [The Shorebird Guide, O'Brien, Crossley & Karlson]
The difference in bills can be compared in the next two photos where the Westerns looks much thinner with a pointed tip. Structural differences can still be compared even if the Western (L) is in basic plumage while the Eastern (R) is in alternate plumage.
The following photo is of an Eastern Willet in breeding plumage. Eastern Willets in full non-breeding plumage are undocumented in North America as they complete their pre-basic moults in South America.
Westerns are less angular, longer bodied and heavier chested. At rest Westerns look more rounded compared to the more oval shape of the Easterns. Westerns are said to have a more godwit-like structure. [Birding - May/June 2006]
Below is a comparison of silhouettes created by Michael O'Brien taken from Birding - May/June 2006.
The white wing stripe both above and below are usually more extensive in Westerns. As with size differences, there is also overlap in this wing characteristic as well. This along with other traits such as size, structure and overall colour should be combined to identify to subspecies. [Birding - May/June 2006]
See the following links for additional information plus many comparison photos.
Michael O'Brien's Article in Birding May/June 2006
The Eastern Willet winters in South American while the Western Willet spends the non-breeding season on both the Pacific and Altantic coasts. The northern extreme of the Western's wintering range on the Atlantic Coast is New Jersey. Willets sighted in Nova Scotia after early September are found to be mostly of the Western subspecies as most of our breeding birds have already left. [All the Birds of Nova Scotia, Ian McLaren]
I found my first Western Willet on October 4, 2014 on the flats in Pubnico Harbour. The following is a distant photo of this bird. If they do ever decide to split this species I'll have another NS lifer up my sleeve.
 |
| Western Willet - October 4, 2014 - Pubnico, Yarmouth County |
Western Willets are usually noticeably larger (10% larger) than Easterns but there is overlap due to the size variability in the Westerns. Some male Westerns overlap with Easterns in size. Westerns are lighter and less brown in all plumages and have a heavy chest. Easterns have a shorter, heavier and thicker tipped bill. [The Shorebird Guide, O'Brien, Crossley & Karlson]
The difference in bills can be compared in the next two photos where the Westerns looks much thinner with a pointed tip. Structural differences can still be compared even if the Western (L) is in basic plumage while the Eastern (R) is in alternate plumage.
 |
| Western (L) vs Eastern Willet (R) |
The following photo is of an Eastern Willet in breeding plumage. Eastern Willets in full non-breeding plumage are undocumented in North America as they complete their pre-basic moults in South America.
 |
| Eastern Willet - July 7, 2013 - Pubnico, Yarmouth County |
Westerns are less angular, longer bodied and heavier chested. At rest Westerns look more rounded compared to the more oval shape of the Easterns. Westerns are said to have a more godwit-like structure. [Birding - May/June 2006]
 |
| Western (L) vs. Eastern (R) |
Below is a comparison of silhouettes created by Michael O'Brien taken from Birding - May/June 2006.
 |
| Western (L) vs. Eastern (R) from Birds May/June 2006 |
The white wing stripe both above and below are usually more extensive in Westerns. As with size differences, there is also overlap in this wing characteristic as well. This along with other traits such as size, structure and overall colour should be combined to identify to subspecies. [Birding - May/June 2006]
Below is a comparison photo from Michael O'Brien's article in Birds May/June 2006.
 |
| Western (R) vs. Eastern (L) from Birds May/June 2006 |
Ian McLaren has provided me with some head/bill ratios comparing both Western and Eastern Willets. Once I review my old statistics notes and if I can make sense of the numbers I'll share them.
See the following links for additional information plus many comparison photos.
Michael O'Brien's Article in Birding May/June 2006
This is great Alix, love the comparison and learning a little bit more.
ReplyDeleteGreat article
ReplyDeleteExcellent info, thanks very much Alix.
ReplyDeleteThanks so much for this Alix. It is very clear. Jane
ReplyDelete