FAMILY PHALACROCORACIDAE d'J 



waters), and on Gatun and Madden lakes; seen occasionally on the 

 lakes near El Volcan at 1280 meters elevation and on the Rio Caldera 

 near Boquete at about 1200 meters. Nesting colonies are reported on 

 Pacheca and Saboga islands in the Perlas group. 



The number of cormorants present on the Gulf varies considerably 

 from season to season, governed apparently by the abundance of the 

 schools of fish that form their food. It seems probable that a part 

 of the great bands that are seen occasionally may be wanderers from 

 other regions in the American tropics. In the early morning of April 

 4, 1948, at the mouth of the Rio Chico, below the La Jagua Hunting 

 Club, tens of thousands flew in lines and irregular bands over the 

 open water of the Gulf. These flocks extended as far as I could 

 see through my binoculars, the total number being far beyond that 

 of the two breeding colonies recorded in the Perlas Islands. Earlier, 

 in February and March 1944, I found flocks of hundreds around 

 Isla San Jose and Isla Pedro Gonzalez, which I believed in the main 

 to be the resident population. In contrast to these observations, in 

 the period from January 16 to 31, 1960, when I was working by 

 seagoing launch through the Archipielago de las Perlas fish were 

 not plentiful, and I recorded only one flock of a hundred cormorants 

 near Isla Contadora, and a few other scattered individuals. Robins 

 (Condor, 1958, p. 302) noted only one during a fishing trip in the 

 Gulf that extended from July 15 to 26, 1957. 



Though so grotesque in form that some find them repulsive, 

 cormorants on closer acquaintance show many interesting habits. The 

 great flocks found at times in the Gulf of Panama are attractive for 

 their numbers alone, as they fly in long lines, 100 to 150 meters 

 above the sea, in search of the schools of small fishes that form their 

 food. When these are sighted the birds circle precipitately down to 

 the water where they swim and dive amid a swarm of swooping 

 frigate birds and laughing gulls, and of plunging pelicans and 

 boobies, while mackerel, amber jack, and other great fishes surge and 

 swirl beneath through the close-packed masses of small fry. No 

 bickering is evident among these active predators, though often I 

 have wondered if there were not frequent collisions that might re- 

 sult in injury, so apparently heedless of one another are the several 

 kinds that join voraciously in the attack. 



At a distance the dark forms of cormorants suggest geese by 

 their size and manner of flight. When hunger is satisfied the flocks 

 rest on rocks on the headlands or on sandy beaches where they 

 stand close together in rows, often in the wash of little waves. As 



