COMPARAÇÃO DA EFICIÊNCIA DE FORRAGEIO DAS GARÇAS EGRETTA CAERULEA E EGRETTA THULA NO ESTUÁRIO DE PARANAGUÁ, PARANÁ, SUL DO BRASIL
DOI:
https://doi.org/10.4257/oeco.2021.2501.06Keywords:
birds, foraging, mangrove, PelecaniformesAbstract
A eficiência de forrageio das aves, resultado do balanço entre consumo e gasto de energia, pode variar conforme condições locais. A eficiência de forrageio foi comparada entre Egretta thula (adulto N = 11) e Egretta caerulea (adulto N = 62 e jovem N = 17) no estuário da cidade de Paranaguá, Paraná, Brasil. Em 14 h de observações divididas em sessões de 2 minutos por indivíduo, foram registrados locais de forrageio (lodo ou águas rasas), número de passos, bicadas totais e bicadas bem-sucedidas, e calculadas taxas de sucesso, esforço energético e eficiência de captura. Em águas rasas E. thula foi mais eficiente que E. caerulea. Não houve diferença para E. thula entre os ambientes, enquanto adultos de E. caerulea foram mais eficientes que os jovens, com maior eficiência no lodo do que em águas rasas. Diferenças na eficiência de forrageio entre as espécies podem ter relação com o tipo de forrageio entre elas dependendo da localidade.
COMPARISON OF EGRETTA CAERULEA AND EGRETTA THULA FORAGING EFFICIENCY IN ESTUARY OF OF PARANAGUÁ, PARANÁ, SOUTHERN BRAZIL: The foraging efficiency of birds may vary according to local conditions as a result of the balance between energy consumption and expenditure. The foraging efficiency of Egretta thula (adults n=11) and Egretta caerulea (adults n=69 and juveniles n= 17) was compared in Paranaguá city estuary, in Paraná, Brazil. In 14 hours of observation divided into 2 minutes sessions per individual, were recorded foraging site (mud or shallow water), number of steps, total peckings and successful peckings, and were calculated the success rates, energy effort and capture efficiency. In shallow water E.thula was more efficient than E. caerulea. There was no intraspecific differences in E. thula regarding environments. Adults of E. caerulea were more efficient than juveniles, with greater efficiency in mud than in shallow waters environments. Differences in foraging efficiency between species may be related to the type of foraging according to feeding location.
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