The Forster Tern 



FORSTERI, and not hirundo, is really 

 the "common," middle-sized tern of Cali- 

 fornia. Whether upon the interior lakes, 

 where it reigns supreme, or upon the bars 

 and beaches of southern California, it is 

 the only member of the forsteri — hirundo- 

 paradiscea group which the casual observer 

 is likely to encounter. In migrations this 

 species appears freely along the coasts, and 

 it undoubtedly mingles more or less with 

 migrating hirundo, for specimens of both 

 species have been taken at a single dis- 

 charge. 1 And yet we judge that forsteri 

 does not occur so often nor so abundantly 

 in the great off-shore movement, and that 

 it exhibits a greater proprietary attachment 

 than do the other species for the brackish 

 lagoons and harbor bars. 



As in the case of so many other shore- 

 bird species, the migratory movement of 

 forsteri is rapid and business-like in spring 

 but more leisurely and diffused in the fall. 

 Forster's Tern is preeminently a marsh- 

 loving species, and its summer range in- 

 cludes such of our larger lakes as have 

 shallow borders, and the great overflow areas 

 tributary to the San Joaquin and Sacramento 

 rivers. The birds arrive in late April or early May, but they take only 

 a languid interest in local affairs until late May or early June, or until 

 such time as the water levels for that season are fairly established. The 

 Forster Tern is one of those species which is peculiarly at the mercy of 

 the elements. Normally, it constructs a well ordered cone (a shallow 

 frustum, to be exact) of green herbage, water-weeds, and half-laced 

 sedges, with contents lifted well above the moist earth ; but frequent exper- 

 ience of disastrous flood has driven the birds to adopt various expedients. 

 Chief among them is the seizure of other nests more fortunately conceived, 

 as for example, those of the Western Grebe (sEchmophorus occidentalis) . 

 Although the grebe has a cruel beak, she seems unable, or unwilling, to use it 

 in self-defense, and will not contest possession with the saucy tern, even 

 though her own eggs be half incubated. The nest shown in the illustra- 

 tion on page 1446 happened to be a fresh one, upon which the tern had 



1 Notably at Hyperion in Los Angeles County. See Condor, Vol. XVI., p. 41. 



Taken in Merced County Photo by the Author 



A SYLPH-LIKE CREATURE 



1444 



