Sources of variation in the nesting success of understory tropical birds

Abstract

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=0.91 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.

Tropical montane birds have increased nesting success on small river islands

“…In general, the nests we placed above ground in vegetation (domes and cups) suffered more predation than ground nests, which is consistent with results from previous studies (Loiselle and Hoppes 1983, Auer et al 2007, Brawn et al 2011, Roldán-Clarà et al 2013). These differences may result from differences in predator searching strategy: Nests located in vegetation above the ground, such as cup and dome nests, were located more reliably than ground nests.…”

“…Avian nesting success is principally affected by nest predation (Ricklefs 1969, Skutch 1985, Brawn et al 2011. Behavior before birds start nesting, during incubation, or during the nestling period can decrease nest predation risk (Ricklefs 1969, Skutch 1985, Brawn et al 2011.…”

“…Behavior before birds start nesting, during incubation, or during the nestling period can decrease nest predation risk (Ricklefs 1969, Skutch 1985, Brawn et al 2011. For example, selecting sites inaccessible to nest predators (e.g., islands) is an important nesting strategy to reduce nest predation risk (Robinson 1985, Boag 1987, Martin 1987, 2001, Lloyd 2004.…”

Breeding biology of African grey parrot (<i>Psittacus erithacus</i>) in Kom National Park (South-Cameroon) and implications to the species conservation

“…Yet several studies have shown that the probability of nest survival is also influenced by habitat and nesting sites (Burke and Nol, 2000;Newmark and Stavley, 2011), the types of nests and nesting phases (Brawn et al, 2011). This result also shows that the behaviour of couples (Supervisory degree of nest) regardless of the type of vegetation is of major importance in contributing to the breeding success.…”

“…This breeding success of GP in the study area although high, remains low compared to the results for other African parrots such as the Cape parrot (Poicephalus robustus) in South Africa with 78% of nests success (Wirminghaus et al, 2002), more than 75% for grey-headed parrot (Poicephalus fuscicollis) of Zimbabwe and South Africa (Symes and Perrin, 2004). It has already been shown that nesting success is generally higher for species that nest in tree cavities (Brawn et al, 2011). In fact, benefits of cavity nesting include shelter from external elements, energy conservation, and greater protection from predators (Rhodes et al, 2009).…”