[302.] BIRDS OF OREGON 



on the back, where these markings are confluent into great blotches or longitudinal 

 bands." (Bent) Si%e: "Length 14-15, wing 9.50-10.30, bill 1.50-1.65, tail 5.00- 

 7.70, forked for 2.. 30-5.00." (Bailey) Nest: In Oregon and other western States, a 

 floating mass of decaying cattails or tules, the eggs being deposited in a neat depres- 

 sion above the water (Plate 49, B). Eggs: 2. to 6, usually 3 or 4. Ground color 

 olive to buff, marked and spotted with dark browns. 



DISTRIBUTION. General: Breeds throughout temperate North America, from Alberta 

 and Manitoba south to Gulf coast and west to central Oregon and California. 

 Winters from southern California and Gulf coast southward. In Oregon: Breeds in 

 Klamath (Klamath Lake), Lake (Warner and Summer Lakes), and Harney (Mal- 

 heur Lake) Counties in great shallow alkaline lakes and marshes. Arrives in April 

 and remains until October. 



FORSTER'S TERN is the most common Oregon representative of the medium- 

 sized terns of swallowlike flight, black cap, and forked tail. It unques- 

 tionably ranks with the most beautiful and graceful of all birds in flight, 

 during \vhich it displays not only beauty of action but beauty of form 

 and color as well. The soft pearl gray of its back and the jet black of 

 its head in the breeding plumage contrast beautifully with the snowy 

 whiteness of the remainder of its body (Plate 49, 5). To observe these 

 beautiful birds at their best, one must again go to the great alkaline 

 marshes of interior Oregon, where they may be seen winging their way 

 over the marshes or waterways, wheeling, turning, darting, or hovering 

 a moment before diving headlong into the water after some luckless 

 minnow. They are fairly common summer resident and breeding birds of 

 Harney, Lake, and Klamath Counties from the middle of April (April 

 14, Klamath County) until some time in October (latest date, October 14, 

 Harney County), but are seen in other parts of the State only as stragglers 

 or in migration. When their nesting colonies are invaded, they will dart 

 and dive at the intruder, uttering raucous cries as they fly, displaying 

 great bravery and determination in their attempts to drive the intruder 

 away. Eggs are laid in May or early June. Our earliest date is May 6; 

 our latest, June n. 



The food of this tern consists almost entirely of small fish, principally 

 of the top-minnow type, and water insects. Two stomachs taken in May 

 192.3 from Warner Lakes were examined. One contained two Leuciscus, a 

 small minnow; and the other, one Mylocheilus caurinus. A September 

 stomach from Klamath Falls contained only fragments of fish bones. As 

 do most fish-eating birds, this tern almost invariably swallows a fish 

 head first to facilitate its passage down the throat. Digestion is extremely 

 rapid, as it is in many other water birds, and the fish's head may be 

 entirely dissolved in the tern's stomach while the tail is still intact in 

 the throat. The birds certainly do no harm to any economic interests in 

 the State by their food habits, and they add a most attractive feature to 

 central Oregon landscape. 



