Nest-site selection and breeding success of two neotropical austral migrant birds in a semiarid forest: A comparison of sites with and without livestock (original) (raw)
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Nest-site selection and breeding success of passerines in the world’s southernmost forests
PeerJ, 2020
Background Birds can maximize their reproductive success through careful selection of nest-sites. The ‘total-foliage’ hypothesis predicts that nests concealed in vegetation should have higher survival. We propose an additional hypothesis, the ‘predator proximity’ hypothesis, which states that nests placed farther from predators would have higher survival. We examined these hypotheses in the world’s southernmost forests of Navarino Island, in the Cape Horn Biosphere reserve, Chile (55°S). This island has been free of mammalian ground predators until recently, and forest passerines have been subject to depredation only by diurnal and nocturnal raptors. Methods During three breeding seasons (2014–2017), we monitored 104 nests for the five most abundant open-cup forest-dwelling passerines (Elaenia albiceps, Zonotrichia capensis, Phrygilus patagonicus, Turdus falcklandii, and Anairetes parulus). We identified nest predators using camera traps and assessed whether habitat characteristics ...
Breeding Biology of Passerines in a Subtropical Montane Forest in Northwestern Argentina
The Condor, 2007
The breeding ecology of south temperate bird species is less widely known than that of north temperate species, yet because they comprise a large portion of the world's avian diversity, knowledge of their breeding ecology can contribute to a more comprehensive understanding of the geographic diversity of avian reproductive traits and life history strategies. We provide the first detailed examination of the reproductive strategies of 18 forest passerines of subtropical, northwestern Argentina. Mean clutch sizes were smaller and egg mass was greater than for north temperate birds, but differed among species and nest types, with cavity-nesters having larger clutches than species with opencup and enclosed nests. Across all species, the average breeding season duration was 50 days; thus, the common perception that southern species have smaller clutch sizes because of longer breeding seasons is not supported in this community. Daily nest predation rates were influenced by nest type, cavity nests suffering the least from predation, as found in north temperate systems. Only females incubated eggs in all but one species, whereas both parents fed and cared for nestlings in all species. Mean nest attentiveness was low compared to north temperate passerines. Mean hourly nestling feeding rates differed among species and were negatively related to nest predation risk. In short, coexisting species in this subtropical forest varied in their life history strategies, in part correlated with variation in nest predation risk, but also differing from north temperate species.
Article, 2018
We present novel data on breeding ecology and nest survival of the Cinereous (Circus cinereus) and Long-winged (C. buffoni) Harriers in modified grasslands of southern Argentina and weevaluate variations in daily nest survival rates (DSR) in relation to temporal and habitat variables. We studied three mixed nesting colonies embedded in agricultural landscapes along a road. We found that DSR decreased linearly with time of breeding and increased with vegetation height above the nest and the distance to the road. This is the first and most complete reproductive study concerning two species of conservation concern, namely the Cinereous and Long-winged Harriers in Patagonia. Our study provides valuable and novel insights into the population dynamics of these little-known species.
Emu - Austral Ornithology, 2014
Many species of birds exhibit a latitudinal gradient in annual reproductive investment, laying more eggs and producing more nestlings at higher latitudes. However, few studies have evaluated the mechanisms that underlie such patterns and such differences in grassland birds specifically. We monitored nests of Fork-tailed Flycatchers (Tyrannus savana) over two breeding seasons at a tropical site in Bolivia (in 2010-11 and 2011-12) and three breeding seasons at a southern temperate site in Argentina (2010-11, 2011-12 and 2012-13), testing two hypotheses explaining variation in clutch-size among populations: the food-limitation hypothesis and the nest-predation hypothesis. Mean clutch-size and mean brood-size were significantly larger at the temperate study site than at the tropical site. Availability of arthropod food per individual bird was significantly higher at the temperate site. There was no relationship, positive or negative, between rates of nest predation and either clutch-or brood-size, and thus no support for the nest-predation hypothesis. We conclude that food availability explains much of the latitudinal variation in clutch-size in this species. We discuss avenues for future research on the mechanisms underlying geographical variation in the life histories of Neotropical birds.
Brazilian Journal of Biology, 2007
Nest and or nest site reuse within and between breeding seasons was reported by the Euler's Flycatcher (Lathrotriccus euleri), the Sepia-capped Flycatcher (Leptopogon amaurocephalus) and the Gray-hooded Flycatcher (Mionectes -rufiventris) in forest fragments from southeastern Brazil. Nest and or nest site reuse between some years was frequent within a single breeding season by the Sepia-capped Flycatcher. Nest reuse, however, was not related to nesting success in the previous breeding attempt. Nest turnover rates (movement to a new site between years) were low for L. amaurocephalus, intermediate for L. euleri and high for M. rufiventris.
Ibis, 2009
The frequency of cavity reoccupation in secondary cavity nesters depends on several factors including quality of cavities, degree of nest-site fidelity, competition with other cavity nesters and availability of new cavities. Blue-fronted Parrots Amazona aestiva are secondary cavity nesters that live in subtropical forests and savannas of central South America. We examined the characteristics of the trees and cavities used by this species in a protected area of the dry Chaco of Argentina and estimated nest-site fidelity and cavity reoccupation. We also assessed whether the probability of cavity reoccupation was associated with cavity characteristics and nesting success during the previous year. Nest-site fidelity of banded females was 68% and cavity reoccupation by banded and unbanded individuals 62%. Probability of reoccupation was associated with wall thickness and depth of the cavity, and was lower if the nest failed the previous year than if it was successful. The high rate of cavity reoccupation in Blue-fronted Parrots is largely attributable to strong nest-site fidelity and may reflect preferences for cavities whose characteristics are associated with higher nesting success.
The Auk, 2015
Avian reproductive strategies have been hypothesized to vary with elevation. Shorter breeding seasons due to harsh environmental conditions, and potentially higher predation risks, may reduce clutch sizes at higher elevations, which in some species leads to increased parental care and offspring survival. However, this phenotypically plastic and potentially adaptive response has been documented only in a handful of species in the Northern Hemisphere. For the first time in a southern temperate ecosystem, we studied whether the breeding strategy of a secondary cavity-nester varied along an elevational gradient in Andean temperate forests, Chile. We installed 240 nest-boxes at 260–1,115 m elevation and monitored the breeding activity of 162 nests of Thorn-tailed Rayaditos (Aphrastura spinicauda) over 2 seasons (2010–2012). We included 50 nests from a third season only for recording clutch size and nestlings per clutch. As predicted, the breeding season was shorter in highland forests than in lower elevations, by 28% and 55% over the 2 successive seasons. Although timing of egg laying (1 egg every second day) and incubation period (average¼15 days) did not vary with elevation, we found smaller clutch sizes (average ¼ 4.1 vs. 4.5) and fewer nestlings per clutch (average ¼ 3.5 vs. 4.2) at higher elevations. The extent of parental care, expressed as the duration of the nestling period, was slightly but significantly greater in highland than in lowland forests (22.2 vs. 21.6 days). Despite the longer nestling period at higher elevations, nesting success was lower at high elevations, mainly because of nest predation. Our findings suggest that Thorn-tailed Rayaditos may change to a slower reproductive strategy along elevational gradients. Yet these changes do not appear to compensate for the increased predation rates at higher elevations, calling into question the potential adaptive significance of this strategy.
Sources of variation in the nesting success of understory tropical birds
Journal of Avian Biology, 2011
Survival of offspring is a key fitness component and, for birds, the threat of predation on nests is especially influential. Data on rates of nest success from tropical regions are comparatively few, conservation-relevant, and essential for assessing the validity of models comparing the life histories and behavior or birds across latitudinal gradients. We monitored over 2 000 nests in the lowland forests of central Panama and, using the logistic exposure to model the fate of nests, explored the importance of variation in rate of nest success according to type of nest, height of nests, among years, in early versus late nests, and at different stages of the nest cycle. Analyses of over 1 400 nests for 18 species revealed considerable variation among species in the daily survival rate of nests (range among 18 species 00.91 to 0.98), but nest type and stage of the nesting cycle were generally influential on the probability of nest success. Cavity or enclosed nesters experienced greater nest success than open cup nesters and rates of nest loss were generally greatest in the nestling stage. We found limited evidence that height of nests affected probability of success, but no indication that timing of nesting effort was influential. Despite the occurrence of a severe ENSO event during our sampling, annual variation in nest success was not consistent among species. Interspecific variation in the rates and patterns of nest predation in our study, coupled with reports of high rates of nest loss at temperate latitudes, lead us to question long standing assumptions about latitudinal trends in rates of nest loss. We urge further work to understand the implications of nest predation on the evolutionary ecology of tropical birds.
Ibis, 2018
Human activities impact upon natural habitats used by birds for breeding and foraging, and lead to changes in the composition and spatial distribution of predator communities, mainly through loss, fragmentation and disturbance of formerly pristine habitat. Yet possible fitness consequences of such changes through impacts on bird nest‐site selection remain poorly known. Here we study nest‐site selection and reproductive success of Placid Greenbuls Phyllastrephus placidus in the Taita Hills, southeast Kenya. We show that habitat features associated with nest‐site selection by this insectivorous, open‐cup‐nesting bird species vary among forest fragments that are exposed to different levels of habitat disturbance. Such differences in sites selected for breeding result from a plastic response to fragment‐specific conditions or may be driven by fragment‐specific variation in the distribution and availability of certain habitat features. Given the overall high nest predation rates in our s...