02468naa a2200277 a 450000100080000000500110000800800410001910000150006024500710007526000090014652017840015565000110193965000090195065000130195965000130197265000100198565000120199565000120200765000120201965300290203165300090206065300260206965300210209565300120211677300620212818108582017-03-27       2003    bl ---       0--  u    #d1 aCAMPOS, Z.  aCaiman crocodilus yacare (Pantanal Caiman). Food related movement.  c2003  aCrocodilians move for many reasons (Lang 1987. In Webb, Manolis and Whitehead [Ed.], Wildlife Management: Crocodiles and Alligators, pp. 273-294. Surrey Beatty & Sons, Chipping Norton, New South Wales). Caiman crocodilus yacare occur in high densities in seasonally flooded habitats in the Brazilian Pantanal (Coutinho and Campo 1996. J. Trop. Ecol. 12:741-747), and food shortages during the dry season have the potential to influence movement. As Santos et al. (1966. Herpetol. J. 6:111-117) mentioned large number adults and tadpoles of Pseudis paradoxa (or soaps) in diet of caiman in the brackish ponds, here I report changes in caimans density potentially linked to changes in soap density in a lake in the Brazilian Pantanal. Observations were made on the Nhumirim Ranch (18 59'S, 56 40'W), Mato Grosso do Sul, Brazil over the period 1989-1999. During night surveys, caiman were counted and soap densities were estimated. One alkaline lake (pH of 9.0-9.9) generally had relatively few (10-34) caiman during each of 20 times it was surveyed. Only two surveys recorded high densities of caiman (&gt500), but each coincided with high densities of P. paradoxa. In each case, I estimated soap densities on the edge of the lake to be &gt 100 adults and large tadpoles/m2. On 10 April 1999, we marked 20 caimans of the several hundred present in the lake during the soap eruption. After 150 days, one marked female was recaptured in a river area 5 km away and the total number of caiman we detected in the lake was reduced to 20. These observations suggest that caiman move in response to change in prey density. I thank Sandra Santos and Max Pinheiro for help with surveys in 1989 and Henrique de Jesus, Jose Augusto Silva and Vandir Silva for assistance with capture of caiman.  aBrazil  adiet  aPantanal  aAlimento  aDieta  aHabitat  aJacaré  aRéptil  aCaiman crocodilus yacare  aFood  aMovimento relacionado  aRelated movement  aReptile  tHerpetological Reviewsgv.34, n.2, p.140-141, June, 2003.