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1.
《Ostrich》2013,84(1):93-96
Nest predation is the leading cause of reproductive failure in birds and thus it shapes their life history strategies. Intensities of nest predation appear to differ among nest locations and types in both temperate and tropical regions. However, there is limited knowledge of factors influencing susceptibility of avian nests to predation in Africa. The aim of our study was to investigate artificial nest predation rates of different ground and shrub nests located at different heights in the rainforest undergrowth. We placed artificial avian nests within a homogeneous lowland forest interior with sparse forest undergrowth in the Mount Cameroon National Park, Cameroon. We exposed three sets of nests: 50 bare-ground, 50 cup-ground and 50 cup-shrub nests, for 10 d. Predation was higher for cup-ground nests compared to cup-shrub nests, and bare-ground nests were more depredated than cup-ground nests. We concluded that the presence of a cup as well as higher nest position significantly increased probability of artificial nest survival. The results of this study suggest a potential selection pressure on nest type and placement in lowland forest birds for a poorly known tropical region.  相似文献   

2.
    
Nest predation is the leading cause of nesting failure. Thus it is a crucial area of research needed to inform conservation management and to understand the life history of birds. I surveyed the literature to review the identity of nest predators and the factors affecting nest predation, in Australia using 177 studies. Overall, 94 nest predators were identified when incorporating artificial nests, 69 without. Using only natural nests, the Pied Currawong Strepera graculina was the most frequently reported nest predator. Five nest predators, including Pied Currawong, depredated 40% of the prey measured by the number of prey species taken. Yet, 60% of predation was carried out by the other 64 species, which included by the order of importance birds, mammals, reptiles, frogs and ants. Predation at cup and dome nests was more frequently reported than at burrow, ground and hollow nests. Only 28% of predators were observed at both artificial and natural nests suggesting artificial nests have limited, but not negligible, ability as tools for identifying predators. There was a highly significant and positive correlation between predator and prey masses. The predator prey mass ratio was calculated with a mean 0.25 and a median 0.22, a result closely matching with the proportional size of prey taken by raptors. The finding that predator size is proportional to prey opens a pathway for more life history and conservation research.  相似文献   

3.
    
Nest predation is assumed to be an important factor driving avian life histories. Altitudinal gradients offer valuable study systems to investigate how avian nest predation risk varies between bird populations. In this study, a hypothesis postulating an increase in avian nest survival rate with elevation as a result of decreasing predation pressure was experimentally tested along an altitudinal gradient (300‐2250 m) in West‐Central Africa. Three types of artificial nests (cup‐shrub, cup‐ground and bare‐ground) were used along the altitudinal gradient. Overall, elevation had no effect on the daily survival rate (DSR) of the artificial nests. However, there was a significant elevation‐nest type interaction. Daily survival rate for cup‐shrub nests decreased significantly with elevation, but for cup‐ground and bare‐ground nests, elevation had no significant effect. We tested the effects of the same vegetation parameters (tree density, herb and shrub layer coverage, and canopy openness) on the DSR of different nest types to understand how different vegetation layers or combinations of them affect DSR. Daily survival rate for bare‐ground nests significantly decreased with increasing canopy openness, and was positively influenced by coverage of herb layer and tree density. For cup‐shrub nests, DSR increased significantly with increasing shrub layer coverage. Finally, for cup‐ground nests, we found a positive effect of shrub coverage and canopy openness on DSR. In summary, we found that different forest vegetation layers affect predation risk of different nest types along elevations on Mt. Cameroon.  相似文献   

4.
    
ABSTRACT Nest‐site selection and nest defense are strategies for reducing the costs of brood parasitism and nest predation, two selective forces that can influence avian nesting success and fitness. During 2001–2002, we analyzed the effect of nest‐site characteristics, nesting pattern, and parental activity on nest predation and brood parasitism by cowbirds (Molothrus spp.) in a population of Brown‐and‐yellow Marshbirds (Pseudoleistes virescens) in the Buenos Aires province, Argentina. We examined the possible effects of nest detectability, nest accessibility, and nest defense on rates of parasitism and nest predation. We also compared rates of parasitism and nest predation and nest survival time of marshbird nests during the egg stage (active nests) with those of the same nests artificially baited with passerine eggs after young fledged or nests failed (experimental nests). Most nests (45 of 48, or 94%) found during the building or laying stages were parasitized, and 79% suffered at least one egg‐predation event. Cowbirds were responsible for most egg predation, with 82 of 107 (77%) egg‐predation events corresponding to eggs punctured by cowbirds. Nests built in thistles had higher rates of parasitism and egg predation than nests in other plant, probably because cowbirds were most active in the area where thistles were almost the only available nesting substrate. Parasitism rates also tended to increase as the distance to conspecific nests increased, possibly due to cooperative mobbing and parental defense by marshbirds. The proportion of nests discovered by cowbirds was higher for active (95%) than for experimental (29%) nests, suggesting that cowbirds used host parental activity to locate nests. Despite active nest defense, parental activity did not affect either predation rates or nest‐survival time. Thus, although nest defense by Brown‐and‐yellow Marshbirds appears to be based on cooperative group defense, such behavior did not reduce the impact of brood parasites and predators.  相似文献   

5.
    
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   

6.
    
Ground-nesting species are vulnerable to a wide range of predators and often experience very high levels of nest predation. Strategies to reduce nest vulnerability can include concealing nests in vegetation and/or nesting in locations in which nests and eggs are camouflaged and less easy for predators to locate. These strategies could have important implications for the distribution of ground-nesting species and the success rates of nests in areas with differing vegetation structure. However, the factors influencing the success of nest concealment and camouflage strategies in ground-nesting species are complex. Here we explore the effects of local vegetation structure and extent of nest concealment on nest predation rates in a range of ground-nesting, sympatric wader species with differing nest concealment strategies (open-nest species: Oystercatcher Haematopus ostralegus, Golden Plover Pluvialis apricaria and Whimbrel Numenius phaeopus; concealed-nest species: Black-tailed Godwit Limosa limosa, Redshank Tringa totanus and Snipe Gallinago gallinago) in south Iceland, in landscapes that comprise substantial variability in vegetation structure at a range of scales. We monitored 469 nests of these six wader species in 2015 and 2016 and ~40% of these nests were predated. Nest predation rates were similar for open-nest and concealed-nest species and did not vary with vegetation structure in the surrounding landscape, but nest-concealing species were ~10% more likely to have nests predated when they were poorly concealed, and the frequency of poorly concealed nests was higher in colder conditions at the start of the breeding season. For concealed-nest species, the reduced capacity to hide nests in colder conditions is likely to reflect low rates of vegetation growth in such conditions. The ongoing trend for warmer springs at subarctic latitudes could result in more rapid vegetation growth, with consequent increases in the success rates of early nests of concealed-nest species. Temperature-related effects on nest concealment from predators could thus be an important mechanism through which climate change affecting vegetation could have population-level impacts on breeding birds at higher latitudes.  相似文献   

7.
魏颐凊  崔国发 《生态学杂志》2014,25(12):3451-3457
人工巢能提高鸟类繁殖成功率,在濒危鸟类保护中已取得显著成效.本文对黑龙江洪河自然保护区东方白鹳天然巢结构特征和人工巢利用情况进行了调查,应用单因素方差分析比较未利用的人工巢、已利用的人工巢和天然巢的结构差异.结果表明: 3种巢穴的支架直径、支架夹角、支架交点高及巢位高等结构因子均存在显著差异.结合天然巢结构特征,东方白鹳人工巢架立柱直径应在15.0~25.0 cm,高度5.0~12.0 m,使用水泥等抗酸性腐蚀材料建造.支架数量应为3~4个,直径9.0~12.0 cm,夹角45°~60°,长度90.0~140.0 cm.  相似文献   

8.
    
Grass Wrens Cistothorus platensis build two types of non-breeding nest structures: platforms and dummy nests. Platforms are rudimentary accumulations of grasses concealed between vegetation. Dummy and breeding nests are dome-shaped with a similar structural layer. We used a nest-removal experiment and observational data to evaluate several hypotheses regarding the adaptive significance of building multiple nests in a south temperate population of Grass Wrens. Building non-breeding nests was not a strategy of males to attract additional females, as most of these nests were built after pair formation and both sexes collaborated during building. Building non-breeding nests was not a post-pairing display as the presence of multiple nests did not increase female investment in the breeding attempt: clutch size and female provisioning to nestlings did not differ between experimental and control territories where no non-breeding nests were removed. Similarly, in non-manipulated territories, clutch size and female provisioning were not correlated with the number of non-breeding nests or with males’ nest-building effort. Contrary to this hypothesis, the number of non-breeding nests was associated with delayed clutch initiation and reduced hatching success. The presence of non-breeding nests did not reduce nest predation and brood parasitism, which did not differ between experimental and control territories. We did not detect differences in concealment between non-breeding and breeding nests, suggesting that non-breeding nests were not the result of abandonment before egg-laying to reduce subsequent nest predation. Dummy nests did not provide shelter; they were not used frequently for roosting over the breeding season and were not maintained during the non-breeding season. We suggest that building non-breeding nests may be an attempt by males to manipulate the decision of females to breed with a mate they might otherwise reject or to start reproduction earlier than optimal for the females.  相似文献   

9.
Summary Birds show much interspecific variation in the coloration and brightness of their plumage. I examine the hypothesis that selection due to predation on incubating birds and their nest contents can explain part of this diversity. First, I argue that rather than using absolute rates of nest predation to make predictions about the costs of conspicuous colours, we should measure experimentally whether increases in plumage conspicuousness elevate rates of nest predation. Second, I present experimental data investigating the cost of red and brown colour at ground and tree nests. These data provide the first evidence that bright colours do attract predators to nests and that, in addition, this cost varies according to the nesting site. Natural selection seems to most strongly oppose the evolution of conspicuous colours in ground-nesting birds.  相似文献   

10.
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   

11.
为了了解保护区内外的白冠长尾雉繁殖生态,2014年3—7月在河南董寨国家级自然保护区和保护区外湖北平靖关村利用人工巢试验(以鸡蛋为诱饵)、红外相机技术和栖息地样方调查搜集巢捕食信息,对其巢捕食率、巢潜在捕食者和影响巢捕食的栖息地因子进行研究.两轮试验分别为繁殖期前期3—4月和繁殖期中期5—6月.试验共放置巢149个,其中红外相机监测62个,累计相机日1315个,拍摄照片7776张,视频6950个.结果表明: 保护区外(平靖关)巢捕食率高于保护区内(董寨),繁殖期前期和繁殖期中期保护区内外差异均极显著.平靖关捕食者种类数(11和6种)在繁殖期前期和中期均高于董寨(7和5种),平靖关捕食者比例较高的是啮齿类和鸦科鸟类,董寨捕食比例较高的是貉.平靖关坡度和乔木盖度对巢捕食影响显著,而董寨的落叶盖度对其影响显著.在红外监测的人工巢中共发现野生白冠长尾雉访问人工巢13巢18次.  相似文献   

12.
13.
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   

14.
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   

15.
    
Mistletoes are preferred nesting sites for many bird species in a range of habitats. However, no studies have examined the use of mistletoes by nesting birds in the semi‐arid savannah. We studied nesting in mistletoe and its role in determining nesting success in the Grey Go‐away‐bird in south‐west Zimbabwe. We modelled the effects of mistletoe, mistletoe abundance, nest microclimate, concealment and nest height on daily survival rates (DSR) using program MARK. A constant survival model was best fitted for the Grey Go‐away‐bird suggesting a constant nest survival rate across the nesting period. Mistletoe nests had lower DSR than nests placed elsewhere in the canopy. Mistletoe abundance and nest height had a positive association with DSR whereas visibility distance, microclimate and concealment were negatively associated with DSR. Overall, survival for nests in mistletoe was 22.1% compared with 90.5% for nests in other substrates over the 50‐day nesting period. In conclusion, the low nest survival in mistletoe suggests either that the factors used to select mistletoe as nest sites by these birds are poor predictors of nest success or that nesting in mistletoe may be maladaptive.  相似文献   

16.
17.
    
ABSTRACT.   Monitoring bird nests with cameras provides an opportunity to identify the cause of nest failure and record the behavior of individuals. However, leaving an object continuously within sight of a nest could have potential negative effects on nesting success. We compared daily survival rates of nests monitored using cameras and human visitation to nests tracked via human visitation only to test for potential additional effects of camera monitoring on predation rates. From 2006 to 2008, experiments were conducted on Bylot Island (Nunavut) using 80 artificial nests and 53 real nests of Baird's Sandpipers ( Calidris bairdii ) and White-rumped Sandpipers ( Calidris fuscicollis ). Rates of predation on real and artificial nests varied considerably among years. However, survival rates of camera-monitored nests did not differ from those of nests monitored without cameras. Predators of artificial nests included Arctic foxes ( Vulpes lagopus ), Glaucous Gulls ( Larus hyperboreus ), and Long-tailed Jaegers ( Stercorarius longicaudus ), whereas Arctic foxes were responsible for all camera-recorded predation events at real nests. Camera monitoring should be promoted as a viable method for monitoring nests of Arctic shorebirds because our results indicate that placing cameras at nests does not bias estimates of nest survival obtained via nest visits.  相似文献   

18.
Åke Berg 《Oecologia》1996,107(3):343-346
Predation rates on artificial wader nests, solitary curlew (Numenius arquata) and lapwing (Vanellus vanellus) nests and lapwing nests in colonies were studied on a farmland site in central Sweden. Predation rates were highest on artificial wader nests, intermediate on solitary curlew and lapwing nests and lowest on lapwing nests in colonies, probably because of active defence of adults at real nests and/or because of selection of nest sites with lower predation risk by breeding birds. A comparison of nests close to (50 m) and far away from (200 m) forest edges revealed no increased predation risk close to edges for any of the studied nest types. Predation risk changed during the season for artificial nests (highest in the middle of May), while predation rates on lapwing and curlew nests were more stable. Artificial nests seem to be inappropriate for measuring actual predation rates and temporal differences in predation rates on real nests, but they might be suitable for use as an index of spatial differences.  相似文献   

19.
For many animals, nest construction is a prerequisite for successfulbreeding. The choice of nesting materials is an important componentof nest construction, because material properties can influencenest design and, potentially, reproductive success. Common waxbillsare small African finches that select carnivore scat as a materialto include in, on, and around their nests. I investigated thehypothesis that scat functions to reduce predation risk by documentingits use in a wild population of common waxbills and by conductingan artificial nest experiment. Among natural nests, scat waspresent in every nest that hatched young, and parents continuedto add scat to nests throughout the nestling period. Among artificialnests, those that received experimental additions of carnivorescat survived at a significantly higher rate than did untreatednests, suggesting that scat functions to reduce predation risk.The mechanism by which nests are protected remains unclear,although it is likely that scat acts as an olfactory deterrentand/or camouflage. Researchers have long focused on the implicationsof nest site characteristics for avian life-history evolution.Results of the present study suggest that nest materials, similarto nest sites, may influence life histories of nest-buildinganimals by affecting predation risk.  相似文献   

20.
  总被引:2,自引:0,他引:2  
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