Aves Rapaces De Chile Pdf Free
it is important to note that, despite the high detection frequency for the barn owl, a high percentage of vocalisations (38%) were not detected. the high detection rate of barn owls in this study could be due to the fact that the study was carried out in a temperate rainforest where the activity of most prey species is diurnal, such as rodents, reptiles and amphibians, and these prey species are more active at night than during the day (fernández-juricic & maldonado 2009 ; fernández-juricic, niemela & maldonado 2011 ). for the pygmy owl, the rufous-legged owl and the austral pygmy owl, the vocalisations were commonly detected in the morning, but not in the afternoon. this result was similar to the diurnal habits of the three owl species in temperate rainforests of southern chile (galassi et al. 2006 ; martin 2011 ). the vocalisation rate of the three owl species detected in this study, especially the rufous-legged owl, was higher in the morning than in the afternoon.
some birds of prey are considered key predators of free-ranging predators, such as the barn owl. previous studies on the influence of carnivores on the breeding success of barn owls have shown that the presence of diurnal or nocturnal predators within a home range can have a significant negative effect on the number of young produced by this species (see larsson et al.; neuheiser et al. 2001). however, the outcome of this interaction is likely to be species-specific, with the effect on each predator species being different (see larsson et al. in this study, we examined the effect of the presence of predators on the breeding success of two raptors, the austral pygmy owl and the rufous-legged owl. our results show that the presence of the small diurnal raptor, the black falcon, had no significant effect on the breeding success of the austral pygmy owl or the rufous-legged owl. the vocalisations of the two raptors had a negligible effect on the breeding success of the austral pygmy owl and the rufous-legged owl.
from january 2011 to december 2018, we systematically searched cnm for the franklin’s gull (pato, cahn’s gull, l. cahistla (gmelin, 1790)). we conducted six surveys to each cnm and recorded bird detections by day of year (doy) and month using a standardized protocol (cordoba et al. 2007 ). detection surveys were conducted during the second week of each month (doy 156, 177 and 208), when birds would have been expected to be at their peak song rate (j. moreno 2017 ). we also recorded the occurrence of the otus vittatus species, the closest avian predator. otus vittatus is common in cnm (popoluca & jaffrelot, 1981) but is only present during the breeding season (august – november) and a nocturnal generalist predator that attacks a wide range of birds, insectivores and small rodents. franklin’s gull is an opportunistic winter visitor (veloso-fras 2018 ) to southern chile (popoluca & jaffrelot, 1981).
from february to december 2011, we conducted acoustic surveys at cnm daily during the second week of the month (doy 176) to record vocalisations. we recorded franklin’s gulls singing the two most-often monitored vocalisations, the contact pair call and territorial call (johnson & kiley 1976 ). we used the automatic playback method (solís, aguilar & moreno 2001 ), an open-source software developed by j.m. moreno for aves acoustic recording, classification and playback using a logitech wave x8 usb audio interface (aves website (moreno j., 2014). we conducted playback at each cnm site and broadcast at 08:30hrs, 13:30hrs, 18:30hrs, 23:00hrs and 01:00hrs. using the automatic playback method, we recorded vocalisations from franklin’s gulls for 7 consecutive days for each cnm, totaling 208 days. we recorded the same vocalisation for each cnm every day, except when weather conditions prevented playback. we measured the following variables: number of vocalisations per contact pair; mean call duration; proportion of contact pairs that produced contact pair calls; proportion of territorial calls; proportion of territorial calls produced at distance s and f locations; minimum distance of contact pair calls; minimum distance of territorial calls; proportion of contact pairs that produced territorial calls over 60 seconds; proportion of territorial calls produced at distance s and f locations; and the proportion of contact pairs that produced territorial calls over 60 seconds at location s (we considered the proportion of territorial calls at location s for comparison with studies about more than one site, because the proportion of territorial calls at location s at cnm are very similar to proportion of territorial calls at site f at cnm). we recorded the number of franklin’s gulls on the surveys, but we did not record the sex of franklin’s gulls, its size, or any additional information. franklin’s gulls were assumed to be adult-sized individuals at cnm during the breeding season.