Área de vida, padrões de atividade e abundância de Martins-pescadores (Aves: Alcedinidae) no Sul do Brasil

Abstract

Between April 2017 and December 2018, studies were conducted on abundance, home range and activity pattern of Megaceryle torquata, Cloroceryle amazona and Chloroceryle americana, three species of kingfishers. Samples were taken from a stretch of Arroio Cambaizinho, a stream located in Santa Margarida do Sul municipaly, Rio Grande do Sul. This stream is a tributary of the Vacacaí River, belonging to the Laguna dos Patos hydrographic system. The stream has an average width of 15 meters and alternates stretches of small rip tides and somewhat deep low flow locations. 407 activity records, 74 forage records and 269 heights of perches records were obtained. The birds’ activity covered the whole period of daylight and a larger number of records in the summer photoperiod were observed. In this photoperiod, kingfishers decreased their activity during the hours with the highest incidence of sunlight and higher temperatures. Although birds also showed lower activity at these times, they also demonstrated to enjoy warmer periods in the morning during the winter photoperiod. Foraging activity was not completely overlapped, although some activity peaks were at the same time. C. americana uses different food resources from the others and showed no difference in activity hours. On the other hand, C. amazona and M. torquata use similar food resources, and differences in hours of activity may mean a mechanism to avoid competition for interference. The height of the perch used by kingfishers increased positively with the body size. In this study the kingfishers demonstrated a similar overall activity period but also a different foraging activity period between species. Partitioning of food resources using other prey types or sizes, and different foraging strategies were also found. These are important mechanisms that allow species to coexist and, as there are no limited food resources, the species in question exhibited behaviors that reduced competition for interference. The population size estimates for the study area were 3.7 individuals of C. amazona and 4.25 individuals of C. americana. The population density of C. amazona was estimated at 7.1 individuals / km² and 5.4 individuals / km² of C. americana. For C. amazona the estimated home range varied from 0.48 km² to 0.69 km². For C. americana, the estimated minimum home range varied from 0.47 to 0.93 km². For M. torquata, the estimated minimum home range was 0.61 km². This is the first study of kingfisher movement patterns, abundances and living area sizes in Brazil and provides important background information on 11 these species ecology. Based on our results, apparently C. americana occupies a distinct niche while C. amazona and M. torquata show a greater overlap mainly by the type of prey captured.