Predation on the southwestern Atlantic fiddler crab (Uca uruguayensis) by migratory shorebirds (Pluvialis dominica, P-squatarola, Arenaria interpres,and Numenius phaeopus)

In Bahia Samborombon (SW Atlantic; 35 degrees 39'-36 degrees 22'S; 56 degre es 45'-57 degrees 23'W) migratory American golden plover (Pluvialis dominic a), black-billed plover (P. squatarola), ruddy turnstone (Arenaria interpre s), and whimbrel (Numenius phaeopus) forage on fiddler crabs (Uca uruguayen sis). These shorebirds have distinct patterns of feeding behavior and captu re different proportions of each sex and size. I dominica made short runs, capturing mostly juvenile crabs, which are eaten whole. P. squatarola use a similar feeding strategy but capture females primarily. A. interpres walks continuously, capturing almost exclusively large male crabs (71%). N. phae opus walk in the Uca patch and probe burrows by inserting the bill; they pr imarily capture females. The feeding rate of A. interpres is higher than th at of P. dominica, I squatarola, and N. phaeopus Handling time shown by P. dominica and A. interpres was greater than the other two species for all ca tegories of crabs. In all cases, handling time of male crabs was greater th an those of either females or juveniles. All the evidences suggest that U. uruguayensis is an important food source for all these species and should b e accounted in any conservation endeavor.