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1.
Joseph Mwangi Henry K. Ndithia Rosemarie Kentie Muchane Muchai B. Irene Tieleman 《Journal of avian biology》2018,49(8)
Nest survival is critical to breeding in birds and plays an important role in life‐history evolution and population dynamics. Studies evaluating the proximate factors involved in explaining nest survival and the resulting temporal patterns are biased in favor of temperate regions. Yet, such studies are especially pertinent to the tropics, where nest predation rates are typically high and environmental conditions often allow for year‐round breeding. To tease apart the effects of calendar month and year, population‐level breeding activity and environmental conditions, we studied nest survival over a 64‐month period in equatorial, year‐round breeding red‐capped larks Calandrella cinerea in Kenya. We show that daily nest survival rates varied with time, but not in a predictable seasonal fashion among months or consistently among years. We found negative influences of flying invertebrate biomass and rain on nest survival and higher survival of nests when nests were more abundant, which suggests that nest predation resulted from incidental predation. Although an increase in nest predation is often attributed to an increase in nest predators, we suggest that in our study, it may be caused by altered predator activity resulting from increased activity of the primary prey, invertebrates, rather than activity of the red‐capped larks. Our results emphasize the need to conduct more studies in Afro‐tropical regions because proximate mechanisms explaining nest predation can be different in the unpredictable and highly variable environments of the tropics compared with the relatively predictable seasonal changes found in temperate regions. Such studies will aid in better understanding of the environmental influences on life‐history variation and population dynamics in birds. 相似文献
2.
Gleidson Ramos da Silva Pedro Diniz Aureo Banhos Charles Duca 《Ecology and evolution》2019,9(13):7402-7409
Road construction is considered to be one of the primary causes of forest fragmentation, and little is known about how roads affect bird reproductive success. The objective of this study was to assess the survival rate of artificial nests along an edge associated with a highway and in the interior of a tabuleiro forest. The study was performed at the Sooretama Biological Reserve, on the margins of federal highway BR‐101, between September and October 2015. A total of 168 artificial nests with a Common quail (Coturnix coturnix) egg in each nest were placed along six sampling transects, at distances of 2, 25, 50, 100, 200, 400, and 800 m from the highway toward the forest interior. We used logistic regression and estimated daily survival rate (DSR) using the “Nest Survival” function in the program MARK to estimate artificial nest survival and assessed the effect of the distance from the highway. The artificial nest survival rate was significantly higher on the highway margins than at other distances. The results show that artificial nests located up to 25 m from the highway have a greater success probability (over 95%) and a significant decrease in success probability more than 50 m from the highway. Although we cannot rule out other nonroad‐specific edge effects on artificial nest predation, our results suggest that the impacts of the highway (e.g., noise, vibration, visual stimuli) cause predators to avoid the road's surroundings (up to 25 m into the forest) when selecting their feeding sites, which partially supports the predation release hypothesis. 相似文献
3.
W. Andrew Cox Frank R. Thompson III Jennifer L. Reidy John Faaborg 《Global Change Biology》2013,19(4):1064-1074
Increased temperatures and more extreme weather patterns associated with global climate change can interact with other factors that regulate animal populations, but many climate change studies do not incorporate other threats to wildlife in their analyses. We used 20 years of nest‐monitoring data from study sites across a gradient of habitat fragmentation in Missouri, USA, to investigate the relative influence of weather variables (temperature and precipitation) and landscape factors (forest cover and edge density) on the number of young produced per nest attempt (i.e., productivity) for three species of songbirds. We detected a strong forest cover × temperature interaction for the Acadian Flycatcher (Empidonax virescens) on productivity. Greater forest cover resulted in greater productivity because of reduced brood parasitism and increased nest survival, whereas greater temperatures reduced productivity in highly forested landscapes because of increased nest predation but had no effect in less forested landscapes. The Indigo Bunting (Passerina cyanea) exhibited a similar pattern, albeit with a marginal forest cover × temperature interaction. By contrast, productivity of the Northern Cardinal (Cardinalis cardinalis) was not influenced by landscape effects or temperature. Our results highlight a potential difficulty of managing wildlife in response to global change such as habitat fragmentation and climate warming, as the habitat associated with the greatest productivity for flycatchers was also that most negatively influenced by high temperatures. The influence of high temperatures on nest predation (and therefore, nest predators) underscores the need to acknowledge the potential complexity of species' responses to climate change by incorporating a more thorough consideration of community ecology in the development of models of climate impacts on wildlife. 相似文献
4.
When a habitat becomes fragmented and surrounded by another habitat this generally causes an increase in predation pressure at habitat transitions, often referred to as an edge effect. Edge effect in the form of enhanced nest predation intensities is one of the most cited explanations for bird population declines in fragmented landscapes. Here, we report results from a nest predation experiment conducted in a tropical montane forest landscape in the Uzungwa Mts., Tanzania. Using artificial nests with chicken eggs, we determined predation rates across a fragmentation gradient. The proportion of indigenous forest in four landscapes used in the study were 0.29, 0.58, 0.75 to 1.0. Nest predation intensities on artificial nests were about 19% higher inside intact forest than at edges in fragmented forest landscapes. Furthermore, predation intensities were relatively constant across a forest fragmentation gradient. Our results thus challenge the applicability and generality of the edge effect, derived from studies almost exclusively conducted in temperate regions rather than tropical forest ecosystems. Nest predation levels differences between tropical montane forest and that reported in other forest ecosystems are discussed. 相似文献
5.
Alison Ke Evaristo Cedeño Jordan Karubian Luis Carrasco Fernando Castillo Nelson Gonzales Daniel S. Karp 《Biotropica》2023,55(5):1045-1057
Most studies comparing biodiversity between natural and human-modified landscapes focus on patterns in species occurrence or abundance, but do not consider how different habitat types meet species' breeding requirements. Organisms that use or nest in tree cavities may be especially threatened by habitat conversion due to the loss of their nesting sites. Although cavity-nesting bird diversity is highest in the tropics, little is known about how tropical birds use cavities, how agriculture affects their reproductive biology, and how effective nest boxes could be as a conservation strategy in tropical agriculture. Here, we explored how habitat conversion from tropical forests to pasture affects the abundance, nesting habitat availability, and nest success of cavity-nesting birds in Northwest Ecuador. We conducted bird surveys and measured natural cavity availability and use in forest and agriculture. We also added artificial nest boxes to forest and agriculture to see whether cavity limitation in agriculture would elicit higher use of artificial nest boxes. We found evidence of cavity limitation in agriculture—there were many more natural cavities in forest than in agriculture, as well as more avian use of nest boxes placed in agriculture as compared to forest. Our results suggest that it is important to retain remnant trees in tropical agriculture to provide critical nesting habitat for birds. In addition, adding nest boxes to tropical agricultural systems could be a good conservation strategy for certain species, including insectivores that could provide pest-control services to farmers. Abstract in Spanish is available with online material. 相似文献
6.
Corey S. Shake Christopher E. Moorman Michael R. Burchell II 《The Journal of wildlife management》2011,75(4):825-835
The effects of habitat edges on nest survival of shrubland birds, many of which have experienced significant declines in the eastern United States, have not been thoroughly studied. In 2007 and 2008, we collected data on nests of 5 shrubland passerine species in 12 early successional forest patches in North Carolina, USA. We used model selection methods to assess the effect of distance to cropland and mature forest edge on nest predation rates and additionally accounted for temporal trends, nest stage, vegetation structure, and landscape context. For nests of all species combined, nest predation decreased with increasing distance to cropland edge, by nearly 50% at 250 m from the cropland edge. Nest predation of all species combined also was higher in patches with taller saplings and less understory vegetation, especially in the second year of our study when trees were 4–6 m tall. Predation of field sparrow (Spizella pusilla) nests was lower in landscapes with higher agricultural landcover. Nest predation risk for shrubland birds appears to be greater near agricultural edges than mature forest edges, and natural forest succession may drive patterns of local extirpation of shrubland birds in early successional forest patches. Thus, we suggest that habitat patches managed for shrubland bird populations should be considerably large or wide (>250 m) when adjacent to crop fields and maintained in structurally diverse early seral stages. © 2011 The Wildlife Society. 相似文献
7.
Using continuous video recording, we identified predation as the main cause of nest failure of understorey‐nesting birds in an intact evergreen forest in northeastern Thailand. Our dataset of 87 predation events is the largest recorded in the tropics. The main predators were macaques (n = 38; 43.7%), nocturnal snakes (n = 19; 21.8%), non‐raptorial birds (n = 12; 13.8%), raptors (n = 6; 6.9%), squirrels (n = 5; 5.7%) and tree shrews (n = 4; 4.6%). The two most important predators, Pig‐tailed Macaque Macaca nemistrina and Green Cat Snake Boiga cinerea, showed no preference for nest type, nest stage or nest height and we found no difference in their relative predation rates among years. Predation was predominantly diurnal (73.6%), suggesting that visual cues may be important for predators at this site. 相似文献
8.
KAREL WEIDINGER 《Ibis》2009,151(2):352-360
I used time-lapse videotaping to identify predators of open songbird nests in fragmented deciduous woodland (nine plots, 2–10 ha each) in the Czech Republic from 2002 to 2006. I documented 22 species of predators at 171 nests of 13 species (mainly Blackcap Sylvia atricapilla , Song Thrush Turdus philomelos , Common Blackbird Turdus merula , Yellowhammer Emberiza citrinella and Chaffinch Fringilla coelebs ). The main predators were Pine Marten Martes martes (37% of 178 predation events), Jay Garrulus glandarius (29%), Buzzard Buteo buteo (7%) and Great Spotted Woodpecker Dendrocopos major (7%); mammals accounted for 48% of total predation. At least 3% of nests were depredated by multiple predators. In spite of their local abundance, Hooded Crows Corvus cornix did not present a serious threat for shrub nesting songbirds (< 1% of total predation). No predation by mice was recorded, suggesting that their importance has been overestimated in artificial nest studies. The proportional species composition of predators depended on which species occupied the monitored nest and location (study plot), but not on the year or the time of season. Corvids and raptors accounted for a relatively larger percentage of total predation of small ('warblers') and large ('thrushes') prey species, respectively, whereas carnivores were important predators of all prey species. Active nests of thrushes were only rarely robbed by Jays (< 4% of 52 events), presumably due to parental nest defence. Predation by woodpeckers was spatially clumped, probably due to individual foraging specialization. Predation by the other major predators was documented on most/all study plots. 相似文献
9.
Catherine M. Young Kristal E. Cain Nina Svedin Patricia R. Y. Backwell Sarah R. Pryke 《Ethology : formerly Zeitschrift fur Tierpsychologie》2017,123(1):41-50
In avian systems, nest predation is one of the most significant influences on reproductive success. Selection for mechanisms and behaviours to minimise predation rates should be favoured. To avoid predation, breeding birds can often deter predators through active nest defence or by modifying behaviours around the nest (e.g. reducing feeding rates and vocalisations). Birds might also benefit from concealing nests or placing them in inaccessible locations. The relative importance of these strategies (behaviour vs. site selection) can be difficult to disentangle and may differ according to life history. Tropical birds are thought to experience higher rates of predation than temperate birds and invest less energy in nest defence. We monitored a population of crimson finches (Neochmia phaeton), in the Australian tropics, over two breeding seasons. We found no relationship between adult nest defence behaviour (towards a model reptile predator) and the likelihood of nest success. However, nest success was strongly related to the visibility of the nest and the structure of the vegetation. We found no evidence that adult nest building decisions were influenced by predation risk; individuals that re‐nested after a predation event did not build their nest in a more concealed location. Therefore, predator avoidance, and hence nest success, appears to be largely due to chance rather than due to the behaviour of the birds or their choice of nesting sites. To escape high predation pressures, multiple nesting attempts both within and between seasons may be necessary to increase reproductive success. Alternatively, birds may be limited in their nest‐site options; that is, high‐quality individuals dominate quality nest sites. 相似文献
10.
Jorge H. Vega Rivera Irais Medina Montaño John Rappole Felipe Campos Cerda 《Journal of Field Ornithology》2009,80(3):303-307
ABSTRACT. Nest concealment by vegetation is considered an important factor affecting predation rates for many passerines and, therefore, is frequently measured in studies examining nest predation. However, the time when concealment measurements are made may affect the results of such studies, particularly in highly seasonal ecosystems where characteristics of the vegetation later in the breeding period may differ considerably from those at the time of nest-site selection. We used artificial nests baited with quail ( Coturnix sp.) eggs in a highly seasonal tropical dry forest in Jalisco, western Mexico, to test the effects of seasonal change in concealment on nest predation. We placed 40 open-cup, artificial nests in shrubs at the end of the dry season and again at the beginning of the rainy season in 2007, and monitored the fate of the nests and the degree of concealment by vegetation during both periods. Nest concealment was significantly greater during the wet season than during the dry season. The percentage of nests predated was marginally higher during the dry (100%) than the wet (72.5%) season, and daily nest survival was lower during the dry than the wet season. Our results suggest that, in highly seasonal environments such as tropical dry forests, delayed measurement of nest concealment after nest completion rather than during nesting may constitute a significant source of error. 相似文献
11.
Land-use change in the Sarapiquí region of Costa Rica has resulted in a fragmented forest landscape with abrupt edges between forest and pasture. Forest responses to edge effects vary widely and can significantly affect ecosystem integrity. Our objective was to examine forest structure at 20+ yr old forest-pasture edges in Sarapiquí. Three transects with 0.095-ha plots at seven distances from forest edges were established in each of six forest patches. Stem density, basal area, and aboveground biomass in trees and palms ≥ 10-cm diameter at breast height were measured in all plots. In addition, hemispherical photographs were taken to determine leaf area index, understory light availability, and percent canopy openness. Linear mixed-effects models showed significantly higher tree stem density at forest edges, relative to interiors, a pattern reflected by increased stem density, basal area, and aboveground biomass in small diameter trees (≤ 20 cm) growing near edges. No differences in total tree basal area, aboveground biomass, or hemispherical photograph-derived parameters were detected across the forest edge to interior gradient. The recruitment of small diameter trees following edge creation has contributed to the development of dense vegetation at the forest edge and has aided in the maintenance of similar tree basal area and aboveground biomass between edge and interior environments. These data reflect on the robustness of forest edges in Sarapiquí, a characteristic that will likely minimize future detrimental edge effects and promote a number of high-value environmental services in these forests. 相似文献
12.
Christine A. Ribic David J. Rugg Kevin Ellison Nicola Koper Pamela J. Pietz 《Ecology and evolution》2021,11(11):6913
Although it is common for nestlings to exhibit a strong bias for fledging in the morning, the mechanisms underlying this behavior are not well understood. Avoiding predation risk has been proposed as a likely mechanism by a number of researchers. We used video surveillance records from studies of grassland birds nesting in North Dakota, Minnesota, and Wisconsin to determine the diel pattern of nest predation and fledging patterns of four ground‐nesting obligate grassland passerines (Grasshopper Sparrow (Ammodramus savannarum), Savannah Sparrow (Passerculus sandwichensis), Bobolink (Dolichonyx oryzivorus), and Eastern Meadowlark (Sturnella magna)). We used the nest predation pattern as a surrogate for predation activity to test whether nestlings minimized predation risk by avoiding fledging when predation activity was high and preferentially fledging when predation risk was low. Predation activity was significantly lower starting 3 hr before sunrise and ending 3 hr after sunrise, followed by a transition to a period of significantly higher activity lasting for 4 hr, before declining to an average activity level for the rest of the diel period. There was little evidence that the four grassland bird species avoided fledging during the high‐risk period and Savannah Sparrow fledged at higher rates during that period. All four species had hours during the low‐risk period where they fledged at higher rates, but only Grasshopper Sparrow fledged preferentially during that period. Bobolink and Eastern Meadowlark had multiple hours with high fledging rates throughout the daytime period, resulting in no relationship between probability of fledging and predation risk. Given the species variability in fledging pattern seen in our study, it is unlikely that there is a universal response to any driver that affects time of fledging. Further study is needed to understand the complex interplay between species ecology and drivers such as physiology, energetics, and predation in affecting grassland bird fledging behavior. 相似文献
13.
Brett A. DeGregorio Patrick J. Weatherhead Jinelle H. Sperry 《Ecology and evolution》2014,4(9):1589-1600
- Anthropogenic alteration of landscapes can affect avian nest success by influencing the abundance, distribution, and behavior of predators. Understanding avian nest predation risk necessitates understanding how landscapes affect predator distribution and behavior.
- From a sample of 463 nests of 17 songbird species, we evaluated how landscape features (distance to forest edge, unpaved roads, and power lines) influenced daily nest survival. We also used video cameras to identify nest predators at 137 nest predation events and evaluated how landscape features influenced predator identity. Finally, we determined the abundance and distribution of several of the principal predators using surveys and radiotelemetry.
- Distance to power lines was the best predictor of predator identity: predation by brown‐headed cowbirds (Molothrus ater), corvids (Corvus sp. and Cyanocitta cristata), racers (Coluber constrictor), and coachwhips (Masticophis flagellum) increased with proximity to power lines, whereas predation by rat snakes (Elaphe obsoleta) and raptors decreased. In some cases, predator density may reliably indicate nest predation risk because racers, corvids, and cowbirds frequently used power line right‐of‐ways.
- Of five bird species with enough nests to analyze individually, daily nest survival of only indigo buntings (Passerina cyanea) decreased with proximity to power lines, despite predation by most predators at our site being positively associated with power lines. For all nesting species combined, distance to unpaved road was the model that most influenced daily nest survival. This pattern is likely a consequence of rat snakes, the locally dominant nest predator (28% of predation events), rarely using power lines and associated areas. Instead, rat snakes were frequently associated with road edges, indicating that not all edges are functionally similar.
- Our results suggest that interactions between predators and landscape features are likely to be specific to both the local predators and landscape. Thus, predicting how anthropogenic changes to landscapes affect nesting birds requires that we know more about how landscape changes affect the behavior of nest predators and which nest predators are locally important.
14.
Gustavo A. Londoño Juan Pablo Gomez Manuel A. Sánchez-Martínez Douglas J. Levey Scott K. Robinson 《Ecology letters》2023,26(4):609-620
Tropical montane communities host the world's highest beta diversity of birds, a phenomenon usually attributed to community turnover caused by changes in biotic and abiotic factors along elevation gradients. Yet, empirical data on most biotic factors are lacking. Nest predation is thought to be especially important because it appears to be common and can change selective pressures underlying life history traits, which can alter competitive interactions. We monitored 2538 nests, 338 of which had known nest predators, to evaluate if nest predation changes along a tropical elevational gradient. We found that nest predation decreased with elevation, reflecting the loss of lowland predators that do not tolerate colder climates. We found different “super” nest predators at each elevation that accounted for a high percentage of events, suggesting that selection pressures exerted by nest predator communities may be less diffuse than has been hypothesized, at least for birds nesting in the understory. 相似文献
15.
J. L. GARDNER 《Austral ecology》1998,23(4):311-321
Abstract This study tested the hypothesis that increased predation of experimental nests occurs close to a forest edge in a fragmented agricultural landscape. Artificial nests and eggs of willie wagtails Rhipidura leucophrys and superb fairy-wrens Malurus cyaneus were used in experiments to assess the extent and nature of predation occurring throughout the known breeding seasons of these species. Predators were identified by the imprints they left in plasticine eggs, and by remote photography. Surveys of avian predators were undertaken to investigate the relationship between predation intensity and predator distribution and abundance. Avian predators accounted for almost all predation for which a predator could be identified (96%). Five of seven predator species photographed attacking wagtail nests were corvids or artamids. Fairy-wren nests suffered relatively low rates of predation (29%) compared to wagtail nests (87%). Increased predation at the habitat edge was recorded for wagtail nests only; predation was correlated with the distribution and abundance of predatory avian species. The different extent and pattern of predation on fairy-wren nests could be explained by problems in detecting predation by mammals, and by possible failure of avian predators to locate the cryptic nests. 相似文献
16.
Laura M. Bolt Amy L. Schreier Kristofor A. Voss Elizabeth A. Sheehan Nancy L. Barrickman 《Biotropica》2020,52(3):541-553
Rivers represent natural edges in forests, serving as transition zones between landscapes. Natural edge effects are important to study to understand how intrinsic habitat variations affect wildlife as well as the impact of human-induced forest fragmentation. We examined the influence of riparian and anthropogenic edge on mantled howler, white-faced capuchin, Central American spider monkeys, and vegetation structure at La Suerte Biological Research Station (abbreviated as LSBRS), Costa Rica. We predicted lower monkey encounter rate, tree species richness, and median dbh at both edge types compared to interior and that monkeys would show species-specific responses to edge based on size and diet. We expected large, folivorous–frugivorous howler monkeys and small, generalist capuchins would be found at increased density in forest edge, while large, frugivorous spider monkeys would be found at decreased density in forest edge. We conducted population and vegetation surveys along interior, riparian, and anthropogenic edge transects at LSBRS and used GLMM to compare vegetation and monkey encounter rate. Tree species richness and median dbh were higher in forest interior than anthropogenic edge zones. Although spider monkey encounter rate did not vary between forest edges and interior, howler monkeys were encountered at highest density in riparian edge, while capuchins were encountered at highest density in anthropogenic edge. Our results indicate that diverse forest edges have varying effects on biota. Vegetation was negatively affected by forest edges, while monkey species showed species-specific edge preferences. Our findings suggest that riparian zones should be prioritized for conservation in Neotropical forests. 相似文献
17.
Artificial nest experiments (ANEs) are widely used to obtain proxies of natural nest predation for testing a variety of hypotheses, from those dealing with variation in life-history strategies to those assessing the effects of habitat fragmentation on the persistence of bird populations. However, their applicability to real-world scenarios has been criticized owing to the many potential biases in comparing predation rates of artificial and natural nests. Here, we aimed to test the validity of estimates of ANEs using a novel approach. We related predation rates on artificial nests to population viability analyses in a songbird metapopulation as a way of predicting the real impact of predation events on the local populations studied. Predation intensity on artificial nests was negatively related to the species' annual population growth rate in small local populations, whereas the viability of large local populations did not seem to be influenced, even by high nest predation rates. The potential of extrapolation from ANEs to real-world scenarios is discussed, as these results suggest that artificial nest predation estimates may predict demographic processes in small structured populations. 相似文献
18.
ABSTRACT. Forest fragmentation can create negative edge effects that reduce the reproductive success of birds nesting near the forest/nonforest interface, and threaten bird populations deeper in remnant forest habitats. Negative edge effects may be more pronounced in landscapes that are moderately fragmented, particularly where agriculture is the primary land-use fragmenting forests. Information about the extent and strength of edge effects at a site can help guide conservation actions, and determine their effectiveness. We examined edge effects for birds breeding in a nearly contiguous forest fragmented by relatively narrow agricultural corridors in Illinois (USA). We measured rates of nest predation and brood parasitism for Acadian Flycatchers ( Empidonax virescens ) over a continuum of distances from the edge of an agricultural inholding. Nest predation and brood parasitism were highest near the edge and decreased with increasing distance from the edge. Given the cumulative effects of nest predation and brood parasitism on reproductive success, we determined that forest within 600 m of the inholding was sink habitat. We found, however, that deeper forest interior areas currently serve as source habitat, and that conversion of the entire 205 ha agricultural corridor to forest would add 1350 ha of source habitat for Acadian Flycatchers. Such results provide support for a local conservation strategy of forest consolidation and establish baseline measures necessary to determine the relative effectiveness of any subsequent reforestation efforts. 相似文献
19.
MARINA MAGAÑA JUAN C. ALONSO CARLOS A. MARTÍN LUIS M. BAUTISTA & BEATRIZ MARTÍN 《Ibis》2010,152(1):77-89
Great Bustards Otis tarda have expanded their habitat range from historical occupancy of natural steppes to arable farmland, where the species initially benefited from favourable feeding conditions. More recently, the species has suffered severe declines due partly to agricultural intensification. Nest losses and juvenile mortality are amongst the factors most seriously affecting survival probabilities of many populations of this endangered species, suggesting that management of nesting habitats would bring conservation benefits. We studied nest-site selection in a Great Bustard population of central Spain by radiotracking 42 females for periods of between 1 and 4 years. Females selected nest-sites in fallows or cereal fields, in areas of low patch-type diversity, far from human infrastructure, and with good horizontal visibility. These results suggest that females look for shelter, but also need to have good visibility while incubating, and they support the hypothesis that nest selection is a trade-off between concealment and visibility. We interpret both preferences as adaptations to reduce predation pressure, one of the main causes of nest failure in this species. Nests were placed on slopes significantly orientated to the southeast, which suggests that females also seek sites protected from the cold north-westerly winds that are prevalent in the study area. To reduce nest destruction, harvesting should be delayed as long as possible and habitat conservation measures should not be restricted to lek sites but also include nesting areas, which are frequently located far from leks. 相似文献
20.
Comparative analyses carried out on two different phylogenies of cooperatively and noncooperatively breeding Australian passerine birds (parvorder Corvida) were unable to detect a significant difference in nest predation rates after controlling for body mass and risk of predation due to location of the nest (nest safety). Nest predation rates, however, decrease as nest safety and body mass increase. We suggest that cooperative breeding does not bring about a current net change in rates of nest predation among Australian passerines. Species breeding cooperatively may have developed antipredator strategies that produce results similar to those adopted by noncooperatively breeding species. The function of cooperative breeding may lie outside of antipredator strategies. 相似文献