14 BULLETIN 113, UNITED STATES NATIONAL MUSEUM. 



Egg dates.— Point Barrow, Alaska: Twenty-four records June 12 

 to 27 ; twelve records June 17 to 20. Iceland : Three records May 21, 

 June 1 and 28. 



STERCOKARIUS PARASITICUS (Linnaeus). 



PARASITIC JAEGER. 



HABITS. 



Contributed by Charles Wendell Towntend. 



As one watches a flock of terns whirling like driven snow, now 

 here, now there, and ever and anon plunging for fish, one may some-, 

 times see a dark, hawk-like bird suddenly appear on the scene and 

 spread devastation in the ranks. With relentless energy he singles 

 out and pursues some hapless individual until it drops its prey. This 

 is a jaeger, a gull-like bird, with hawk-like characteristics. A more 

 appropriate name for him would be robber rather than jaeger or 

 hunter, for he obtains his food by robbing other birds. He has, 

 however, all the grace and agility of the true hunting birds — the 

 hawks— but his actions rarely end in bloodshed. After all robbery 

 is a less serious crime than murder, but the term robber is oppro- 

 brious, while that of hunter is not, so it is perhaps well that the name 

 remains as it is. 



The parasitic jaeger is circumpolar in its distribution and breeds 

 throughout the barren arctic grounds in North America, Greenland, 

 Europe, and Asia. In Europe it nests as far south as the Shetlands. 

 It winters from the southern part of its summer range along the 

 coast even as far as Brazil, Australia, and the Cape of Good Hope^ 

 but in the interior of the continents it is only of casual occurence. 



/Spring. — In the brief arctic spring, when the ice is breaking up and 

 the snowdrifts are dwindling, the parasitic jaeger arrives on the 

 breeding grounds on the tundra near the shores of the Arctic Ocean, 

 or at a distance from the sea on the shores of ponds or lakes. It 

 generally nests apart, not in communities. Of its courtship nothing 

 is known. It is possible that the " wailing cries " described by Nelson 

 and mentioned later may be in the nature of the love song. When 

 surprised near the nest, Nelson (1887) says, "it creeps along the 

 ground with flapping wings to decoy away the intruder." 



Nesting. — The nest is a mere depression in the soil. Macfarlane 

 (1908) says it is "scantily lined with a few withered leaves and 

 grasses." Grinnell (1900) in the region of Kotzebue Sound, Alaska, 

 says " the nest was a slight saucer-shaped depression on a low mossy 

 hummock on the tundra. This depression was scatteringly lined 

 with bits of white lichen, such as grow immediately around the 

 nest." Thayer and Bangs (1914) report that Koren found it in 



