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1.
《Ethology, Ecology and Evolution》2012,24(4):361-372
Distinct size dimorphism was found between queens (inseminated egglayers) and workers (uninseminated non egg-layers) sampled from mature colonies of Agelaia pallipes and A. A. multipicta. In both species, among 22 measured body parts queens were larger than workers in 17 characters. The Mahalanobis' distance (D2) between castes was 122.74 in A. pallipes and 110.99 in A. A. multipicta, giving clear-cut evidence of caste separation, a conclusion which is strengthened by the absence of intermediate females. Comparisons with A. vicina and A. flavipennis demonstrated that morphological castes attributes are less developed in A. pallipes and A. A. multipicta. 相似文献
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Oliver Robertson Martine Maron Yvonne Buckley Alan House Clive McAlpine 《Austral ecology》2014,39(3):255-266
Many passerine bird populations, particularly those that have open‐cup nests, are in decline in agricultural landscapes. Current theory suggests that an increase in habitat generalist predators in response to landscape change is partially responsible for these declines. However, empirical tests have failed to reach a consensus on how and through what mechanisms landscape change affects nest predation. We tested one hypothesis, the Additive Predation Model, with an artificial nest experiment in fragmented landscapes in southern Queensland, Australia. We employed structural equation modelling of the influence of the relative density of woodland and habitat generalist predators and landscape features at the nest, site, patch and landscape scales on the probability of nest predation. We found little support for the Additive Predation Model, with no significant influence of the density of woodland predators on the probability of nest predation, although landscape features at different spatial scales were important. Within woodlands fragmented by agriculture in eastern Australia, the presence of noisy miner colonies appears to influence ecological processes important for nest predation such that the Additive Predation Model does not hold. In the absence of colonies of the aggressive native bird, the noisy miner, the influence of woodland predators on the risk of artificial nest predation was low compared with that of habitat generalist predators. Outside noisy miner colonies, we found significant edge effects with greater predation rates for artificial nests within woodland patches located closer to the agricultural matrix. Furthermore, the density of habitat generalist predators increased with the extent of irrigated land‐use, suggesting that in the absence of noisy miner colonies, nest predation increases with land‐use intensity at the landscape scale. 相似文献
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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
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Birds free from nest predators for long periods may either lose the ability to recognize and respond to predators or retain antipredator responses if they are not too costly. How these alternate scenarios play out has rarely been investigated in an avian community whose members have different evolutionary histories. We presented models of two nest predators (rat and snake) and a negative control (tree branch) to birds on Hawai?i Island. Endemic Hawaiian birds evolved in the absence of terrestrial predators until rats were introduced approximately 1,000 years ago. Introduced birds evolved with diverse predator communities including mammals and snakes, but since their introduction onto the island approximately one century ago have been free from snake predation. We found that (a) endemic and introduced birds had higher agitation scores toward the rat model compared with the branch, and (b) none of the endemic birds reacted to the snake model, while one introduced bird, the Red‐billed Leiothrix (Leiothrix lutea), reacted as strongly to the snake as to the rat. Overall, endemic and introduced birds differ in their response to predators, but some endemic birds have the capacity to recognize and respond to introduced rats, and one introduced bird species retained recognition of snake predators from which they had been free for nearly a century, while another apparently lost that ability. Our results indicate that the retention or loss of predator recognition by introduced and endemic island birds is variable, shaped by each species' unique history, ecology, and the potential interplay of genetic drift, and that endemic Hawaiian birds could be especially vulnerable to introduced snake predators. 相似文献
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Nest structures are essential for successful reproduction in most bird species. Nest construction costs time and energy, and most bird species typically build one nest per breeding attempt. Some species, however, build more than one nest, and the reason for this behaviour is often unclear. In the Grey Fantail Rhipidura albiscapa, nest abandonment before egg‐laying is very common. Fantails will build up to seven nests within a breeding season, and pairs abandon up to 71% of their nests before egg‐laying. We describe multiple nest‐building behaviour in the Grey Fantail and test four hypotheses explaining nest abandonment in this species: cryptic depredation, destruction of nests during storm events, and two anti‐predatory responses (construction of decoy nests to confuse predators, and increasing concealment to ‘hide’ nests more effectively). We found support for only one hypothesis – that abandonment is related to nest concealment. Abandoned nests were significantly less concealed than nests that received eggs. Most abandoned nests were not completely built and none received eggs, thus ruling out cryptic predation. Nests were not more likely to be abandoned following storm events. The decoy nest hypothesis was refuted as abandoned nests were constructed at any point during the breeding season and some nests were dismantled and the material used to build the subsequent nest. Thus, Grey Fantails are flexible about nest‐site locations during the nest‐building phase and readily abandon nest locations if they are found to have deficient security. 相似文献
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The population declines of waders in Europe are widely considered to have resulted from habitat loss and degradation due to agricultural changes. However, recent empirical evidence suggests that levels of predation on wader nests are unsustainably high in many cases, even in some situations where breeding habitat is otherwise favourable. We review the published and 'grey' literature on nest predation on waders in Europe and quantify the relative importance of the major predators. Nest cameras offer the least biased method of identifying and quantifying nest predators. A small number of camera studies, in combination with others utilizing nest temperature loggers, indicate that nocturnal/mammalian predators make the largest contribution to wader nest predation. More than half of site-years or studies reviewed reported clutch failure rates of over 50% attributable to predation alone, a rate that is likely to be associated with declining populations, although parameters such as chick and adult survival will also affect population trends. Correlates of wader nest predation are documented, with time of season, field type and management, distance to habitat/field edge, wader nest density, and abundance of mammalian predators being most consistently identified. Future directions of research into wader productivity are discussed, and we suggest that studies quantify additional life-history parameters such as chick survival, as well as examining the predator community, wherever possible. 相似文献
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Among stages of avian ontogeny, the act of nest departure or fledging is an abrupt transition into a new environment and a major leap toward independence for offspring. In altricial birds, the timing (i.e. time of day) of fledging is notable in that many species tend to fledge early in the morning. Past studies have proposed nest predation as a key factor driving birds to fledge earlier in the morning (the ‘survival hypothesis’), whereby offspring avoid peak times of nest predation that occur later in the day. A natural extension of this hypothesis is the predation of offspring post-fledging, whereby offspring are also timing their fledging with future survival prospects outside of the nest. However, few studies have investigated fledging behaviour in the context of both nesting and post-fledging predation. To help fill this knowledge gap, we investigated factors driving the timing and duration of fledging across six songbird species in the context of offspring predation: daily nest mortality, post-fledging mortality and diel patterns of nest predation risk. We found that > 60% of songbirds fledged early in the morning, whereas the peaks in nest predation risk occurred several hours post-fledging. Furthermore, species under greater risk of nest predation fledged earlier in the day and in closer succession to their siblings. Parameters of post-fledging mortality were poor predictors of fledging timing, but individuals from broods of species under higher risk of post-fledging mortality fledged in closer succession to their siblings. These results provide evidence in support of the survival hypothesis, and suggest that songbirds fledge in the morning to avoid peak times of nest predation risk that occur later in the day (~ 8 h after civil dawn). Such results corroborate past research highlighting predation on dependent offspring as a key factor driving variation in life histories across animal taxa; however, estimates of post-fledging mortality suggest that nest predation alone does not fully explain variation in fledging behaviour among species. Future research is therefore needed to investigate the contribution of other factors, such as energetics, parent–offspring conflict and diel patterns of post-fledging survival, which may help to mediate diel patterns of fledging within and among songbird species. 相似文献
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ABSTRACT Improving the conservation status of rare and declining species often requires multiple strategies targeted at several vital rates. We report on one of several ongoing management actions intended to benefit the declining population of Streaked Horned Larks (Eremophila alpestris strigata). To improve Streaked Horned Lark fecundity, we employed predator exclosures (wire cages) around nests (N= 33 exclosed and 32 not exclosed) in 2009 and 2010 at two sites in Oregon and two in Washington with the goal of excluding larger birds, the primary lark nest predators. We found no statistically significant effect of exclosures on nest success. For exclosed nests, lower rates of nest predation (exclosed = 12%, unexclosed = 48%) were offset by higher rates of nest abandonment (exclosed = 27%, unexclosed = 0%). Nest abandonment was likely caused by a variety of factors including American Kestrels (Falco sparverius) perching on exclosures, and predation of adults associated with exclosed nests. Our results suggest that the current exclosure design does not improve Streaked Horned Lark fecundity and may negatively affect adult survival. To improve exclosure effectiveness, we recommend modifications that prevent kestrels from perching on exclosures and deny their access to the nest. We also recommend that modifications be applied in an adaptive management framework that includes close monitoring to assess their effectiveness, and subsequent adaptation that might include continued structural modification of exclosures or discontinued use on some or all sites. 相似文献
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Fire‐maintained Pinus palustris (longleaf pine) ecosystems are species rich and considered a top conservation priority in the southeastern United States. Ground‐nesting species such as Gopherus polyphemus (gopher tortoise) and Colinus virginianus (northern bobwhite) thrive in longleaf ecosystems. However, the generalist carnivore Procyon lotor (raccoon) is a significant predator of these endemic ground nesters. In forested ecosystems, raccoons prefer hardwood‐dominated habitats. Removal of hardwood trees, which is a common longleaf pine ecosystem restoration tool, affects habitat use of this predator. We examined 269 daytime resting sites (DRS) associated with 31 radio‐collared adult raccoons (18 M, 13 F) during 2014–2015 on a longleaf pine‐dominated site in southwestern Georgia. We developed 26 a priori models using an information theoretic approach to evaluate factors affecting use of DRS by raccoons. The top two models (ΔAIC < 2) had combined model weights of 0.75 and contained tree diameter, tree type, presence of nearby hardwood, and distances to pine, hardwood, mixed forest, and agriculture as predictors. However, the only informative variables were tree type and tree diameter. Raccoons used DRS in all available forest types, but were less likely to use pine trees (n = 7) relative to hardwoods (n = 247), and there was a positive relationship with tree diameter. Females used smaller trees farther from agriculture and primary roads, and were closer to wetlands than those used by males. Hardwood removal from within longleaf pine ecosystem affects habitat use of this predator, specifically DRS. 相似文献
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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
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Predation is the main cause of nest failure among birds and, therefore, a strong selective agent. To fully understand patterns of nest predation, determining the identities of nest predators is crucial. Information about nest predators in the Neotropics, however, is largely anecdotal and not easily accessible in the literature. Our objective was to search the literature and compile a list of the known predators of nests in the Neotropics. We identified 256 species belonging to 67 families of birds, reptiles, mammals, and arthropods as nest predators. Families with at least 10 species of identified nest predators included Colubridae, Accipitridae, Corvidae, Ramphastidae, Falconidae, Furnariidae, Icteridae, and Didelphidae. Species in the first five of these families, plus the family Cebidae, predated nests of at least 30 species of birds. Many species not included on our list are also likely nest predators, e.g., 79 species identified as nest predators in the Nearctic that also occur in the Neotropics, but have not yet been confirmed as predators there. Increased use of video technology in the future should lead to an increase in the numbers of nest predators identified, particularly those that are nocturnal. By determining which species on our list occur in a given study area, researchers can now consider the likely nest predators in their study areas when designing hypotheses and conservation plans. 相似文献
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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
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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
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A simple and effective marking technique is an invaluable tool for tracking the movement of invertebrates in the field. In order to do this, the technique must be validated in a controlled setting. In the first study, two soft bodied herbivores with different feeding strategies and two of their insect predators, also with different feeding strategies, were marked with rubidium (Rb), an elemental marker previously shown to be effective in marking herbivorous invertebrates. The naturally occurring concentration of Rb was determined for both the herbivores and their predators. Rb concentrations were determined in (1) the herbivore species over several days of feeding on rubidium chloride (RbCl) marked plants; (2) in the predatory species immediately after consuming prey marked at different rates with Rb; and (3) in the predatory species for several days after consuming a single meal of Rb marked prey. The concentration of Rb within the marked herbivores was found to be significantly higher than the naturally occurring concentration after eating RbCl marked plants for to up 8 days. A significantly higher concentration of Rb was found in both predators when fed prey that had been on the RbCl sprayed plants for 2 or 8 days compared with naturally occurring concentrations. There was also a significant difference between the Rb concentrations in the controls and each of days 5, 10 and 15 since feeding in both predators. A second smaller study was carried out to examine the effect of feeding Rb marked prey to spiders. The concentration of Rb in the spiders fed marked prey was significantly higher than that of the controls. This suggests that Rb is an effective way of marking both herbivores and their insect and arachnid predators enabling them to be tracked in the field and to determine their movements across habitats. 相似文献
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Capsule Dummy birds placed on artificial nests increase nest survival, and their use should be considered in future studies of nest predation. 相似文献
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Summary Breeding habitats in Mediterranean France consist in open, dry grasslands with a low and discontinuous grass layer and scattered bushes and trees. The choice of nest supports was largely opportunistic, the most abundant suitable nest support type (bush or tree) and the most abundant species being present at each study site have been used. About 75% of the nests were placed at heights between 1 and 3 m. Laying period lasted from 9 May until 6 July (peak of first clutches: 21–30 May). Mean clutch size was 5.14±0.82 eggs (n=114). Breeding success was independent from the site, the height and the concealment of nests. Mean survival rate of nests from laying to fledgling was 0.365. The main cause of low breeding success was high nest predation exerted by a rich guild of predators. The species is mainly threatened through dramatic habitat shrinkage due to pastoralism reduction leading to closures of lightly bushed grasslands in Mediterranean France.
Nistplatzwahl, Legeperiode und Bruterfolg des Rotkopfwürgers (Lanius senator) in Südfrankreich
Zusammenfassung Als Bruthabitat bevorzugt der Rotkopfwürgers im mediterranen Südfrankreich offene und trockene Graslandlandschaften mit niedrigem oder lückigem Grasbewuchs und einzelstehenden Büschen und/oder Bäumen. Häufigster Nestträger ist die jeweils im Brutterritorium häufigste Baum- oder Buschart. Ungefähr 75% der Nester standen zwischen 1 und 3 m über Boden. Die Legeperiode reichte vom 9. Mai bis 6. Juli (Gipfel der Erstgelege am 21.–30. Mai und der Ersatzgelege am 20.–24. Juni). Die Gelegegröße bestand aus 3 bis 7, meist 5 Eier (Erstgelege im Mittel 5,35±0,71 Eier, Ersatzgelege: 4,68±0,85). Der Bruterfolg war unabhängig von der Lage, der Höhe und der Verborgenheit des Nestes. Die mittlere Überlebensrate eines Nestes zwischen Bebrütung des Geleges und Ausfliegen der Jungen betrug 0,365. Dieser niedrige Bruterfolg wurde hauptsächlich durch Nesträuber verursacht. In Südfrankreich ist die Art aber vor allem durch die zunehmende Verschließung der Bruthabitate infolge des Rückgangs des extensiven Weidebetriebs gefährdet.相似文献
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