Foam Lake Birding No. 31

No. 31
One thing about being on the coast is that one is inundated with a wide variety of water loving birds – especially gulls. Overall, their numbers are not that great because large quantities of food are simply not available to them nearby. Local ordinances and state and federal laws prohibit dumping of refuse on beaches, thus keeping populations under control However, with heavy human use of beaches, there are always some accidentally dropped or discarded tidbits from picnic lunches and so on. In addition, there is always something dead or dying washing up on shore. When the tides recede, sea life such as clams, crabs, starfish and worms top off the menu. Whatever the food source, gulls, which are not discriminating eaters, do a very thorough job of keeping the beaches clean. Their feeding habits provide a sanitation service far beyond what man could hope to do.
Some gulls can be found both on sea coasts and fresh water lakes; some only on fresh water; the majority only along sea coasts. Today’s featured bird, the Western Gull, belongs to the latter group.
The Western Gull is very similar to many other white headed gulls. Distinctions among the various species are quite subtle. They all have white heads and undersides, and dark wings and back. All, more or less, sound the same. Different species do vary quite considerably in size, but unless they are in mixed flocks this is of little use. An observer has to focus on the colours and markings of the eyes, bills, feet, backs and wings. Only when all field marks fall into place can a positive identification be made.
Above all else, a serious birder should acquire a current bird book with accurate colour pictures and range maps. Poor colour rendition, especially in older bird books, often results in birds being misidentified. Range maps are very helpful, but often under utilized. Through the process of elimination, a birder can use range maps to zero in only on birds that exist in that particular area. For example, the Greater Black Backed Gull is found only on the east coast; whereas the very similar Western Gull is found only on the west coast from southern British Columbia to northern Mexico. A birder in Halifax, upon seeing a white gull with very dark wings and back, would be quite confident that the bird in question is a Greater Black Backed; similarly, with the Western in Victoria. In neither case would one have to differentiate between the two because they do not coexist in the same area.
As mentioned in a previous article, any bird seen far outside its normal range must be identified with great caution and corroborated by credible witnesses. Good quality photographs are a great help, but are not considered proof. For example, it is impossible to determine with any reasonable certainty that the gulls in this week’s picture are Western Gulls. With poor quality photographs, the task becomes almost impossible. Only when the location is known can the birds be safely identified.
This week’s photo was taken in Oceanside, California. In typical gull fashion, the two are sitting on a street light surveying the area and watching for somebody to discard something to eat. It certainly does remind one of gulls sitting on light poles at fast food restaurants back home.