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Thomas E Martin - One of the best experts on this subject based on the ideXlab platform.
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Nest Predation risk and growth strategies of passerine species grow fast or develop traits to escape risk
The American Naturalist, 2012Co-Authors: Yiru Cheng, Thomas E MartinAbstract:AbstractDifferent body components are thought to trade off in their growth and development rates, but the causes for relative prioritization of any trait remains a critical question. Offspring of species at higher risk of Predation might prioritize development of locomotor traits that facilitate escaping risky environments over growth of mass. We tested this possibility in 12 altricial passerine species that differed in their risk of Nest Predation. We found that rates of growth and development of mass, wings, and endothermy increased with Nest Predation risk across species. In particular, species with higher Nest Predation risk exhibited relatively faster growth of wings than of mass, fledged with relatively larger wing sizes and smaller mass, and developed endothermy earlier at relatively smaller mass. This differential development can facilitate both escape from predators and survival outside of the Nest environment. Tarsus growth was not differentially prioritized with respect to Nest Predation risk, ...
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Nest Predation and circulating corticosterone levels within and among species
The Condor, 2011Co-Authors: Joseph J Fontaine, Elena Arriero, Hubert Schwabl, Thomas E MartinAbstract:Variation in the risk of Predation to offspring can influence the expression of reproductive strategies both within and among species. Appropriate expression of reproductive strategies in environments that differ in Predation risk can have clear advantages for fitness. Although adult-Predation risk appears to influence glucocor - ticosteroid levels, leading to changes in behavioral and life-history strategies, the influence of offspring-Predation risk on adult glucocorticosteroid levels remains unclear. We compared total baseline corticosterone concentrations in Gray-headed Juncos (Junco hyemalis dorsalis) Nesting on plots with and without experimentally reduced risk of Nest Predation. Despite differences in risk between treatments, we failed to find differences in total baseline cor - ticosterone concentrations. When we examined corticosterone concentrations across a suite of sympatric species, however, higher risk of Nest Predation correlated with higher total baseline corticosterone levels. As found previ- ously, total baseline corticosterone was negatively correlated with body condition and positively correlated with date of sampling. However, we also found that corticosterone levels increased seasonally, independent of stage of breeding. Nest Predation can alter the expression of birds' reproductive strategies, but our findings suggest that total baseline corticosterone is not the physiological mechanism regulating these responses.
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PARENTAL INVESTMENT DECISIONS IN RESPONSE TO AMBIENT Nest-Predation RISK VERSUS ACTUAL Predation ON THE PRIOR Nest
The Condor, 2010Co-Authors: Anna D. Chalfoun, Thomas E MartinAbstract:Abstract. Theory predicts that parents should invest less in dependent offspring with lower reproductive value, such as those with a high risk of Predation. Moreover, high Predation risk can favor reduced parental activity when such activity attracts Nest predators. Yet, the ability of parents to assess ambient Nest-Predation risk and respond adaptively remains unclear, especially where Nest-predator assemblages are diverse and potentially difficult to assess. We tested whether variation in parental investment by a multi-brooded songbird (Brewer's Sparrow, Spizella breweri) in an environment (sagebrush steppe) with diverse predators was predicted by ambient Nest-Predation risk or direct experience with Nest Predation. Variation among eight sites in ambient Nest-Predation risk, assayed by daily probabilities of Nest Predation, was largely uncorrelated across four years. In this system risk may therefore be unpredictable, and aspects of parental investment (clutch size, egg mass, incubation rhythms, Nestlin...
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Can selection on Nest size from Nest Predation explain the latitudinal gradient in clutch size
Journal of Animal Ecology, 2010Co-Authors: Luis Biancucci, Thomas E MartinAbstract:1. Latitudinal variation in clutch sizes of birds is a well described, but poorly understood pattern. Many hypotheses have been proposed, but few have been experimentally tested, and none have been universally accepted by researchers. 2. The Nest size hypothesis posits that higher Nest Predation in the tropics favours selection for smaller Nests and thereby constrains clutch size by shrinking available space for eggs and/or Nestlings in the Nest. We tested this hypothesis with an experiment in a tropical forest and a comparative study between temperate and tropical field sites. 3. Specifically, we tested if: (i) Predation increased with Nest size; (ii) tropical birds had smaller Nests controlled for body size; and (iii) clutch size was explained by Nest size controlled for body size. 4. Experimental swapping of Nests of different sizes showed that Nest Predation increased with Nest size in the tropical site. Moreover, Nest Predation rates were higher in species with larger Nests in both sites. However, Nest size, corrected for body mass and phylogeny, did not differ between sites and was not related to clutch size between sites. 5. Hence, Nest Predation can exert selection on Nest size as predicted by the hypothesis. Nest size increased with adult body mass, such that adult size might indirectly influence reproductive success through effects on Nest size and Nest Predation risk. Ultimately, however, selection from Nest Predation on Nest size does not explain the smaller clutch sizes typical of the tropics.
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Testing ecological and behavioral correlates of Nest Predation
Oikos, 2007Co-Authors: Joseph J Fontaine, Mireille Martel, Helen M. Markland, Alina M. Niklison, Karie L. Decker, Thomas E MartinAbstract:Variation in Nest Predation rates among bird species are assumed to reflect differences in risk that are specific to particular Nest sites. Theoretical and empirical studies suggest that parental care behaviors can evolve in response to Nest Predation risk and thereby differ among ecological conditions that vary in inherent risk. However, parental care also can influence Predation risk. Separating the effects of Nest Predation risk inherent to a Nest site from the risk imposed by parental strategies is needed to understand the evolution of parental care. Here we identify correlations between risks inherent to Nest sites, and risk associated with parental care behaviors, and use an artificial Nest experiment to assess site-specific differences in Nest Predation risk across Nesting guilds and between habitats that differed in Nest predator abundance. We found a strong correlation between parental care behaviors and inherent differences in Nest Predation risk, but despite the absence of parental care at artificial Nests, patterns of Nest Predation risk were similar for real and artificial Nests both across Nesting guilds and between predator treatments. Thus, we show for the first time that inherent risk of Nest Predation varies with Nesting guild and predator abundance independent of parental care.
Christopher J. Whelan - One of the best experts on this subject based on the ideXlab platform.
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DOES VERTICAL PARTITIONING OF Nest SITES DECREASE Nest Predation
The Auk, 2000Co-Authors: Leonard R. Reitsma, Christopher J. WhelanAbstract:Abstract Partitioning of Nest heights among co-occurring species in response to Nest Predation has been proposed as a process that helps to structure avian species assemblages. In the experiment reported here, we used artificial Nests baited with Japanese Quail (Coturnix japonica) eggs to test (1) whether both rate and final level of Nest Predation differed among Nests placed at ground, shrub, and tree strata; and (2) whether vertical partitioning of Nest sites among the three strata decreased Nest Predation. Although rates of Nest Predation increased from ground, to partitioned, to shrub, to tree strata, the only significant pairwise differences were between Predation on ground Nests versus all other treatments. The proportion of Nests depredated at the conclusion of the experiment was lowest for the ground treatment, intermediate for the partitioned treatment, and highest for the shrub and tree treatments. Predation was significantly higher in 1988 than in 1989, and significant variation in Predation oc...
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Does Vertical Partitioning of Nest Sites Decrease Nest Predation?
The Auk, 2000Co-Authors: Leonard R. Reitsma, Christopher J. WhelanAbstract:Abstract Partitioning of Nest heights among co-occurring species in response to Nest Predation has been proposed as a process that helps to structure avian species assemblages. In the experiment reported here, we used artificial Nests baited with Japanese Quail (Coturnix japonica) eggs to test (1) whether both rate and final level of Nest Predation differed among Nests placed at ground, shrub, and tree strata; and (2) whether vertical partitioning of Nest sites among the three strata decreased Nest Predation. Although rates of Nest Predation increased from ground, to partitioned, to shrub, to tree strata, the only significant pairwise differences were between Predation on ground Nests versus all other treatments. The proportion of Nests depredated at the conclusion of the experiment was lowest for the ground treatment, intermediate for the partitioned treatment, and highest for the shrub and tree treatments. Predation was significantly higher in 1988 than in 1989, and significant variation in Predation occurred among five spatial replicates of the experimental treatments. Although the results show different susceptibilities to Nest Predation according to vegetative stratum, they show only a slight and nonsignificant reduction in Nest Predation as a consequence of vertical Nest-site partitioning.
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Nest Predation on woodland songbirds: When is Nest Predation density dependent?
Oikos, 1999Co-Authors: Kenneth A Schmidt, Christopher J. WhelanAbstract:Nest Predation. if density dependent, may structure avian communities by selecting for Nest-site characteristics that dilute the predators' perception of Nest density (e.g., by increasing the number and types of potential Nest sites) thereby reducing losses to predators. We tested for density dependent Nest Predation at a site dominated by Predation from raccoons, Procyon lotor. and blue jays. Cyanocitta cristata. We used cohorts of 20 artificial ground Nests placed on experimental grids at four densities (1.7, 7, 65, and 167 Nests/ha). Predation was density dependent for one of two temporal replicates. In a second experiment, we tested for density dependent Predation on both ground and shrub Nests using more realistic Nest densities (3.5 and 8.9 Nests/ha) and excluding avian and small mammal predators by placing nylon screening over the Nests. Predation was density dependent on artificial ground Nests and density independent on shrub Nests. Finally, we analyzed Predation on natural shrub Nests separating out avian (i.e., jays) and large mammalian Predation based on disturbance to the depredated Nest. In each of three years there was no evidence for density dependent Predation. An outbreak of periodic cicadas in the first experiment and the maturation of a large mulberry crop during the second experiment demonstrated the importance of the distribution and abundance of alternative foods on the response of predators toward heterogeneity in Nest abundance.
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The Relative Impacts of Nest Predation and Brood Parasitism on Seasonal Fecundity in Songbirds
Conservation Biology, 1999Co-Authors: Kenneth A Schmidt, Christopher J. WhelanAbstract:The impacts of Nest Predation and brood parasitism on the seasonal fecundity of birds are strongly dependent on the number of Nesting attempts, and thus seasonal fecundity is responsive to behavioral traits that increase the number of opportunities to Nest. We developed simple models to investigate the relative im- pacts of Nest Predation and brood parasitism on seasonal fecundity in songbirds. In particular, we asked to what extent songbirds can ameliorate the negative effects of high Nest Predation and brood parasitism often typical of fragmented, urbanized, and agricultural landscapes through (1) reNesting following Predation, (2) abandoning and reNesting following parasitism, and (3) double brooding—reNesting following a successful brood. Our model assigned probabilities to all possible fates of breeding females and calculated seasonal fe- cundity by summing up the individual probabilities. We analyzed the model through the use of fecundity isopleths, which allow one to visually determine the impact of Predation and parasitism simultaneously over the entire range of probabilities. Our analysis indicates that (1) Nest Predation has a greater impact on sea- sonal fecundity over a larger range of parameter space than does parasitism, especially when brood loss due to parasitism is low; (2) songbird populations experiencing Nest Predation probabilities typical of fragmented landscapes ( . 0.65) are unlikely to be self-sustaining; and (3) amelioration of Nest Predation through fre- quent reNesting or double brooding may be insufficient to establish self-sustaining populations. These results suggest that predator control should be at least as high a priority as parasitism control, particularly for spe- cies that suffer moderate to low brood reduction due to parasitism and that are single-brooded. Programs aimed solely at managing cowbirds likely will be of limited success.
Jean Clobert - One of the best experts on this subject based on the ideXlab platform.
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CLUTCH SIZE REDUCTION AS A RESPONSE TO INCREASED Nest Predation RATE IN THE COLLARED FLYCATCHER
Ecology, 2003Co-Authors: Blandine Doligez, Jean ClobertAbstract:Nest Predation has been hypothesized as a major factor influencing clutch size in birds. Indirect and correlative evidence for clutch size reduction under high Nest Predation risk is accumulating, but such a reduction has never been shown experimentally. We experimentally tested this “Nest Predation hypothesis” by manipulating Nest Predation rate in the Collared Flycatcher, Ficedula albicollis. As predicted, clutch size decreased in the year following the experiment in “depredated” areas (in which 20–35% of the Nests were totally depredated) compared to control ones (no Predation). This could result from (1) phenotypic plasticity in clutch size, or (2) differential breeding habitat selection, with dominant individuals or individuals laying large clutches preferentially leaving depredated areas and settling in control ones. There was no evidence for differential dispersal from areas of the two treatments, nor differential competitive abilities of breeders in areas of the two treatments. Conversely, all ind...
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PHENOTYPIC ADJUSTMENT OF CLUTCH SIZE DUE TO Nest Predation IN THE GREAT TIT
Ecology, 1997Co-Authors: Romain Julliard, Robin H. Mccleery, Jean Clobert, Christopher M. PerrinsAbstract:Nest Predation may decrease the optimal clutch size for many reasons. In particular, a smaller clutch size may permit more investment in re-laying or in survival to the next reproductive event. The response to Nest Predation may be either genetic, as shown by comparative studies on birds, or phenotypic, as found in several aquatic species (in- vertebrates and fish). We have studied the effects of several years of high Nest Predation on clutch size variation in a Great Tit (Parus major) population. We tested whether Nest Predation was associated with selection on clutch size or with any phenotypic changes. In the year following peak Nest Predation, mean clutch size was reduced by about one egg. For Nest Predation, adult survival, and local recruitment, we failed to detect any dependence on clutch size; the reduction in clutch size was mostly phenotypic. Similarly, the return of clutch size to pre-Predation values was explained as a phenotypic change. Surprisingly, individuals that did not experience Nest Predation themselves also modified their clutch size. This suggests that information on past Predation persisted in the population for several years. In years with reduced clutch size, adult survival at the population level was higher, suggesting that a reduction in clutch size would be adaptive in case of Nest Predation, and that females adjusted their clutch size toward the optimum.
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Nest Predation and avian life history evolution in europe versus north america a possible role of humans
The American Naturalist, 1996Co-Authors: Thomas E Martin, Jean ClobertAbstract:Life-history theory predicts that decreased mortality in early life can favor increased fecundity and reduced iteroparity. Similar to other causes of environmental variation, modification of the environment by humans potentially can change age-specific mortality and, hence, affect life-history evolution. Forests were removed throughout western Europe long ago, and Nest Predation (early mortality) is reduced in human-settled environments there, whereas Nest Predation is generally increased in areas settled by humans in North America. We controlled statistically for effects of body size and phylogeny and compared songbirds (Passeriformes) of Europe to those of North America and found that Nest Predation was lower in Europe. Associated with this decrease in early mortality in Europe, fecundity was increased and iteroparity was reduced via decreased adult survival rates, as predicted by theory. Moreover, continental differences were greater for species that were more vulnerable to Nest Predation (open-Nesting...
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Nest Predation and delayed cost of reproduction in the great tit
Journal of Animal Ecology, 1996Co-Authors: Robin H. Mccleery, Romain Julliard, Jean Clobert, Christopher M. PerrinsAbstract:1. During a study on the great tit at Wytham Wood, Oxfordshire, Nest Predation by weasels was as high as 50% in some years prior to 1976. In 1976, Nest-boxes were made virtually predator proof. 2. The change in Nest-box type increased local recruitment rate and total population size of great and blue tits. We examined here the consequences of reduced Nest Predation on the survival rate of the great tit late in life. 3. Prior to 1976 (during the Nest Predation period), survival rate after the age of 5 years showed no decline and no relationship to the number of successful breeding attempts in either sex. 4. After 1976 (predator-proof period), both sexes showed increased mortality rates after the age of 5. However, only female survival was related to the number of successful breeding attempts, with a negative correlation. 5. This enhanced mortality late in life is likely to result from an increased cost of reproduction due to the combined effects of increased competition (higher adult density) and increased investment in reproduction (more young to raise because of reduced Nest Predation). These results fit predictions from life history theory, where increased effort early in life is predicted to trade with survival late in life.
Alice W Boyle - One of the best experts on this subject based on the ideXlab platform.
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can variation in risk of Nest Predation explain altitudinal migration in tropical birds
Oecologia, 2008Co-Authors: Alice W BoyleAbstract:Migration is among the best studied of animal behaviors, yet few empirical studies have tested hypotheses explaining the ultimate causes of these cyclical annual movements. Fretwell’s (1980) hypothesis predicts that if Nest Predation explains why many tropical birds migrate uphill to breed, then Predation risk must be negatively associated with elevation. Data from 385 artificial Nests spanning 2,740 m of elevation on the Atlantic slope of Costa Rica show an overall decline in Predation with increasing elevation. However, Nest Predation risk was highest at intermediate elevations (500–650 m), not at lowest elevations. The proportion of Nests depredated by different types of predators differed among elevations. These results imply that over half of the altitudinal migrant bird species in this region migrate to safer breeding areas than their non-breeding areas, suggesting that variation in Nest Predation risk could be an important benefit of uphill migrations of many species.
Ido Izhaki - One of the best experts on this subject based on the ideXlab platform.
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Vegetation structure governs Nest Predation in three types of conifer forest habitats
European Journal of Forest Research, 2020Co-Authors: Uzi Dagan, Ido IzhakiAbstract:The primary hazard for open-cup Nesting birds is Nest Predation. Vegetation structure and coverage may affect Nest Predation through various mechanisms such as the ability of a predator to locate the Nests, which may vary between breeding habitats. We examined the association between vegetation structure and Nest Predation in three different types of pine plantations using artificial Nests of the Sardinian warbler, Sylvia melanocephala, which were located 30 cm above ground in low bushes. We also assessed the relationship between bird abundance and Nest Predation in each type of forest. Finally, we identified predators through their bite marks on 3D-printed plaster eggs that were placed in the Nests. The percentage of Nests predated in pine forests with high understory coverage was significantly higher than in pine forests with only sparse understory. We also found that the Nest Predation rate positively correlated with total bird abundance and the abundance of S. melanocephala . The species of Nest predators varied between different forest types, although rodents and birds were the most and second-most abundant predators, respectively, in each forest type. These results show that patches with only sparse understory vegetation within the forests generate Nesting sites for birds with less risk of Predation. But because bird abundance in this habitat type was relatively low, the net effect of preserving such habitat on the number of hatched birds should be further studied.