Habitat Use and Survival of Preflight Wild Turkey Broods

Abstract: Wild turkey (Meleagris gallopavo) broods spend the first several days of life on the ground until poult flight capabilities are attained. This is a critical period of wild turkey life history, with poult survival ranging from 12% to 52%. We measured vegetation in plots used by Rio Grande wild turkey (M. g. intermedia) preflight broods at 4 sites in southwest Kansas and the Texas Panhandle, USA, to determine microhabitat selection for ground roosting and to determine if microhabitat was related to poult survival. Hens selected ground-roost locations with more visual obstruction from multiple observation heights than random sites. Plots surrounding ground roosts had 1) greater visual obstruction; 2) increased tree decay; 3) higher percent grass, shrub, litter, and forb cover; and 4) lower percent bare ground cover than random sites. Grass, shrubs, and downed trees appeared to provide desired cover for ground-roosting broods. Poult survival increased with age of poult, size of brood, and density of shrubs 1–2 m tall. Plots used by broods <10 days old with above average survival contained more visual obstruction and shrubs than plots used by broods 10–16 days old with above average survival, signifying a shift in habitat use by successful broods as poults attain flight abilities. Density of shrubs 1–2 m tall in brood-use areas appears to be important for poult survival to 16 days of age on southern Great Plains rangeland habitats. Ground-level vegetative cover appears to be a significant factor in preflight poult survival. Provisions of ground-level vegetative cover should be considered during wild turkey brooding periods where increased poult survival is desired.     

Merriam's Turkey Nest Survival and Factors Affecting Nest Predation by Mammals

Abstract: Nest success is an important parameter affecting population fluctuations of wild turkeys (Meleagris gallopavo). Factors influencing mammalian predation on turkey nests are complicated and not well understood. Therefore, we assessed nest hazard risk by testing competing hypotheses of Merriam's turkey (M. g. merriami) nest survival in a ponderosa pine (Pinus ponderosa) ecosystem during 2001–2003. We collected nesting information on 83 female Merriam's turkeys; annual nest success averaged 50% for adult females (range = 45–59%) and 83% for yearling females (range = 75–100%). Proportional hazard modeling indicated that precipitation increased the hazard of nest mortality. However, estimated hazard of nest predation was lowered when incubating females had greater shrub cover and visual obstruction around nests. Coyotes (Canis latrans) were the primary predator on turkey nests. We hypothesize that precipitation is the best predictor of nest survival for first nests because coyotes use olfaction effectively to find nesting females during wet periods. Temporally, as the nesting season progressed, precipitation declined and vegetation cover increased and coyotes may have more difficulty detecting nests under these conditions later in the nesting period. The interaction of concealment cover with precipitation indicated that nest hazard risk from daily precipitation was reduced with greater shrub cover. Management activities that promote greater shrub cover may partially offset the negative effects of greater precipitation events.     

Rio Grande Wild Turkey Habitat Selection in the Southern Great Plains

ABSTRACT We recorded telemetry locations from 1,129 radiotagged turkeys (Meleagris gallopavo intermedia) on 4 study areas in the Texas Panhandle and southwestern Kansas, USA, from 2000 to 2004. Analyses of telemetry locations indicated both sexes selected riparian vegetative zones. Females did not select grazed or nongrazed pastures for daily movements. However, females did select nongrazed pastures for nest sites on 2 study areas and males selected for grazed pastures at one study area during the breeding season. We compared nest sites (n = 351) to random sites using logistic regression, which indicated height of visual obstruction, percent canopy cover, and percent bare ground provided the highest predictive power (P ≤ 0.003) for characteristics describing nest-site selection. Nest-site vegetative characteristics between vegetative zones differed primarily in composition: upland zone nest sites had more (P ≤ 0.001) shrubs and riparian zone nest sites had more (P ≤ 0.001) grass. There were no differences in measured nest site vegetative characteristics between pasture types, but there were differences between available nesting cover in grazed and nongrazed pastures. Random plots in grazed pastures had less grass cover (P ≤ 0.001) and more bare ground (P = 0.002). Because of cattle impacts on average grass height and availability, grazing would likely have the highest impact on nesting in riparian zones due to turkey use of grass as nesting cover. An appropriate grazing plan to promote Rio Grande turkey nesting habitat would include grazing upland zones in the spring, when it likely has little impact on nesting-site selection, and grazing riparian zones following breeding season completion. Grazing at light to moderate intensities with periods of rest did not affect male turkey pasture use and may have continued to maintain open areas used by male turkeys for displaying purposes.     

Hunting Activity Effects on Roost Selection by Male Wild Turkeys

Roosting is an important component of wild turkey (Meleagris gallopavo; turkey) ecology as roosts provide security from predators and inclement weather. Males call (gobble) from roosts during the reproductive season, and roost locations are important for maximizing access to females and transmission of calls across the landscape, while also minimizing predation risk. Spring hunting of male turkeys occurs during the reproductive season, and hunting activity influences male behaviors and calling. Because roost sites are important for wild turkey ecology, we evaluated roost site selection and fidelity of male turkeys relative to land cover types, vegetative characteristics, and the presence of hunting activity during 2017–2018 in Georgia, USA. Prior to onset of hunting, males selected roosts nearest to hardwood and pine (Pinus spp.) forests. Roost site fidelity was low and distances between roosts were large. After onset of hunting, males selected pine forests less and exhibited greater plasticity in roost selection while fidelity remained minimal, suggesting that males may have altered selection to mitigate risk from hunting while maintaining the strategy of moving about their ranges and roosting at different sites on consecutive nights. Future research should examine potential effects of hunting-induced shifts in resource selection on other aspects of male turkey behavior and ecology. © 2019 The Wildlife Society.     

Behavior and Movement of Wild Turkey Broods

Behavioral and movement ecology of broods are among the most poorly understood aspects of wild turkey (Meleagris gallopavo) reproductive ecology. Recent declines in wild turkey productivity throughout the southeastern United States necessitate comprehensive evaluations of brood ecology across multiple spatial scales. We captured and marked 408 female wild turkeys with global positioning system (GPS)-transmitters across 9 pine (Pinus spp.)-dominated study sites in the southeastern United States during 2014–2019. We evaluated various aspects of the behavioral and movement ecology of 94 brood-rearing females until brood failure or 28 days after hatch (i.e., when poults are classified as juveniles). We found that 34 (36.2%) females had broods (≥1 poult) survive to 28 days after hatch. Broods moved >500 m away from nest sites the day after hatching, and then moved progressively farther away from nest sites over time. Daily movements increased markedly the first 3 days after hatching, and broods moved >1,000 m/day on average thereafter. Females roosted broods an average of 202 m away from nest sites the first night after hatching, but distances between consecutive ground or tree roosts were variable thereafter. Daily core areas increased from 0.8 ha the day of hatch to 4.6 ha by day 28, and range sizes increased from 6.9 ha to 27.9 ha by day 28. Broods tended to consistently select open land cover types, whereas selection for other land cover types varied temporally after hatch day. Broods spent 89% of their time foraging. Predicted daily survival for broods decreased rapidly with increasing distance moved during the initial 3 days after hatching and showed less variation during the subsequent 2 weeks post-hatch. Our findings parallel previous researchers noting that the most critical period for brood survival is the first week after hatch day. Previous researchers have attempted to identify vegetative communities used by broods under the assumption that these communities are a primary factor influencing brood success; however, our results suggest that brood survival is influenced by behavioral decisions related to movements during early brooding periods. © 2020 The Wildlife Society.     

Influence of olfactory and visual cover on nest site selection and nest success for grassland‐nesting birds

Habitat selection by animals is influenced by and mitigates the effects of predation and environmental extremes. For birds, nest site selection is crucial to offspring production because nests are exposed to extreme weather and predation pressure. Predators that forage using olfaction often dominate nest predator communities; therefore, factors that influence olfactory detection (e.g., airflow and weather variables, including turbulence and moisture) should influence nest site selection and survival. However, few studies have assessed the importance of olfactory cover for habitat selection and survival. We assessed whether ground‐nesting birds select nest sites based on visual and/or olfactory cover. Additionally, we assessed the importance of visual cover and airflow and weather variables associated with olfactory cover in influencing nest survival. In managed grasslands in Oklahoma, USA, we monitored nests of Northern Bobwhite (Colinus virginianus), Eastern Meadowlark (Sturnella magna), and Grasshopper Sparrow (Ammodramus savannarum) during 2015 and 2016. To assess nest site selection, we compared cover variables between nests and random points. To assess factors influencing nest survival, we used visual cover and olfactory‐related measurements (i.e., airflow and weather variables) to model daily nest survival. For nest site selection, nest sites had greater overhead visual cover than random points, but no other significant differences were found. Weather variables hypothesized to influence olfactory detection, specifically precipitation and relative humidity, were the best predictors of and were positively related to daily nest survival. Selection for overhead cover likely contributed to mitigation of thermal extremes and possibly reduced detectability of nests. For daily nest survival, we hypothesize that major nest predators focused on prey other than the monitored species’ nests during high moisture conditions, thus increasing nest survival on these days. Our study highlights how mechanistic approaches to studying cover informs which dimensions are perceived and selected by animals and which dimensions confer fitness‐related benefits.     

Timing of vegetation sampling does not influence associations between visual obstruction and turkey nest survival in a montane forest

Evaluating relationships between ecological processes that occur concurrently is complicated by the potential for such processes to covary. Ground‐nesting birds rely on habitat characteristics that provide visual and olfactory concealment from predators; this protection often is provided by vegetation at the nest site. Recently, researchers have raised concern that measuring vegetation characteristics at nest fate (success or failure) introduces a bias, as vegetation at successful nests is measured later in the growing season (and has more time to grow) compared with failed nests. In some systems, this bias can lead to an erroneous conclusion that plant height is positively associated with nest survival. However, if the features that provide concealment are invariant during the incubation period, no bias should be expected, and the timing of measurement is less influential. We used data collected from 98 nests to evaluate whether there is evidence that such a bias exists in a study of wild turkey (Meleagris gallopavo) nesting in a montane forest ecosystem. We modeled nest survival as a function of visual obstruction and other covariates of interest. At unsuccessful nests, we collected visual obstruction readings at both the date of nest failure and the projected hatch date and compared survival estimates generated using both sets of vegetation data. In contrast to studies in grassland and shrubland systems, we found little evidence that the timing of vegetation sampling influenced conclusions regarding the association between visual obstruction and nest survival; model selection and estimates of nest survival were similar regardless of when vegetation data were collected. The dominant hiding cover at most of our nests was provided by evergreen shrubs; retention of leaves and slow growth of these plants likely prevent appreciable changes in visual obstruction during the incubation period. When considered in aggregate with a growing body of literature, our results suggest that the influence of timing of vegetation sampling depends on the study system. When designing future studies, investigators should carefully consider the type of structures that provide nest concealment and whether plant phenology is confounded with nest survival.     

Nest‐site selection and productivity of Vesper Sparrows breeding in grazed habitats

ABSTRACT Livestock grazing in the shortgrass steppe of the Intermountain region of British Columbia may have a negative impact on ground‐nesting birds, but evidence of such an impact is lacking. We examined nest‐site selection and productivity of ground‐nesting Vesper Sparrows (Pooecetes gramineus) across sites with different grazing histories. From 2006 to 2008, we monitored Vesper Sparrow nests and measured vegetation characteristics known to be affected by grazing within nest patches. We used an information‐theoretic approach to test the relative importance of grazing‐affected vegetation variables as predictors of nest‐site selection, nest survival, and nestling condition. Vesper Sparrows selected nest sites with greater cover of late‐seral grass species that decrease in occurrence in response to grazing (i.e., “decreasers”) than was available in random patches in the same territories. Daily nest survival was also lower for nests surrounded by shorter vegetation (odds ratio = 1.12). However, “decreaser” cover was not associated with either of the two indices of productivity measured (daily nest survival probability and nestling condition). In addition, vegetation height, although an important driver of success, was not linked with nest‐site selection, and no vegetation‐cover variable was positively associated with productivity, despite nest concealment being central to our predictions. This suggests that predation risk for nests in areas with shorter vegetation was being elevated through some factor unrelated to concealment. Our results show that grazing reduced both the availability of suitable habitat for and nesting success of Vesper Sparrows, indicating that grazing could pose a threat to population persistence at a broader scale and could potentially contribute to observed declines. Additional research is needed to determine if grazing guidelines in the Intermountain region of British Columbia should be amended, better enforced, or both to prevent regional declines in populations of ground‐nesting grassland birds.     

Nest Site Selection by Greater Sage-Grouse in Mono County,California

ABSTRACT Loss of nesting habitat is believed to be a factor in the decline of greater sage-grouse (Centrocercus urophasianus) throughout its range. Few data are available for sage-grouse in Mono County, California, USA, in the most southwestern portion of the species’ range. We studied habitat selection of nesting sage-grouse in Mono County, California, from 2003 to 2005 by capturing and radiotracking females to identify nesting locations. We sampled vegetation at nest sites and randomly selected sites within 200 m of nests and within each of 5 subareas within Mono County. Nest sites were characterized by 42.4 ± 1.3% (x̄ ± SE) shrub canopy cover, 10.5 ± 1.0 cm residual grass height, and 2.7 ± 1.0% residual grass cover. Shrub cover was the only variable found to differentiate nest sites from randomly selected sites. Unlike some other studies, we did not find understory vegetation to be important for selecting nest sites. Mean shrub cover was 38.7 ± 1.5% at random sites within 200 m of nests and 33.6 ± 1.6% at random sites at the approximate scale of home ranges, indicating that nesting females selected nesting areas that contained denser shrubs than their home range, and nest sites that contained greater shrub cover than the vicinity immediately surrounding nests. Our results suggest that managers should consider managing for greater shrub cover in Mono County than what is currently called for in other parts of sage-grouse range and that management for sage-grouse habitat may need to be tied more closely to local conditions.     

Long-billed curlew nest site selection and success in the Intermountain West

Grassland birds have experienced steeper population declines between 1966 and 2015 than any other bird group on the North American continent, and migratory grassland birds may face threats in all stages of their annual cycle. The grassland-associated long-billed curlew (Numenius americanus) is experiencing population declines in regional and local portions of their North American breeding range. The nesting period is an important portion of the annual cycle when curlews may face demographic rate limitations from a suite of threats including predators and anthropogenic disturbance. We compared nest sites to random sites within breeding territories to examine nest site selection, and modeled correlates of nesting success for 128 curlew nests at 5 Intermountain West sites. Nest sites were 6 times more likely than random sites to be situated adjacent to existing cowpies. Additionally, curlews selected nest sites with shorter vegetation, and less bare ground, grass, and shrub cover than at random sites within their territories. Nest success varied widely among sites and ranged from 12% to 40% in a season with a mean of 27% for all nests during the 2015 and 2016 seasons. Higher nest success probability was associated with higher curlew densities in the area, greater percent cover of conspicuous objects (cowpies, rocks) near the nest, and higher densities of black-billed magpies (Pica hudsonia) and American crows (Corvus brachyrhynchos) at the site. We also found increased probability of nesting success with increased distance from a nest to the nearest potential perch in that territory. Given the central role of working lands to curlews in much of the Intermountain West, understanding limitations to nesting success in these diverse landscapes is necessary to guide adaptive management strategies in increasingly human-modified habitats. We suggest some grazing and irrigation practices already provide suitable nesting conditions for curlews, and others may require only minor temporal shifts to improve compatibility. © 2019 The Wildlife Society.     

Strategies for Nest-Site Selection by King Eiders

ABSTRACT Nest site selection is a critical component of reproduction and has presumably evolved in relation to predation, local resources, and microclimate. We investigated nest-site choice by king eiders (Somateria spectabilis) on the coastal plain of northern Alaska, USA, 2003–2005. We hypothesized that nest-site selection is driven by predator avoidance and that a variety of strategies including concealment, seclusion, and conspecific or inter-specific nest defense might lead to improved nesting success. We systematically searched wetland basins for king eider nests and measured habitat and social variables at nests (n = 212) and random locations (n = 493). King eiders made use of both secluded and concealed breeding strategies; logistic regression models revealed that females selected nests close to water, on islands, and in areas with high willow (Salix spp.) cover but did not select sites near conspecific or glaucous gull (Larus hyperboreus) nests. The most effective nest-placement strategy may vary depending on density and types of nest predators; seclusion is likely a mammalian-predator avoidance tactic whereas concealment may provide protection from avian predators. We recommend that managers in northern Alaska attempt to maintain wetland basins with islands and complex shorelines to provide potential nest sites in the vicinity of water.     

Microhabitat nest‐site selection by ducks in the boreal forest

The boreal forest is one of the North America’s most important breeding areas for ducks, but information about the nesting ecology of ducks in the region is limited. We collected microhabitat data related to vegetation structure and composition at 157 duck nests and paired random locations in Alberta’s boreal forest region from 2016 to 2018. We identified fine‐scale vegetation features selected by ducks for all nests, between nesting guilds, and among five species using conditional logistic regression. Ducks in the boreal forest selected nest sites with greater overhead and graminoid cover, but less forb cover than random sites. Characteristics of the nest sites of upland‐ and overwater‐nesting guilds differed, with species nesting in upland habitat selecting nests that provided greater shrub cover and less lateral concealment and species nesting over water selecting nests with less shrub cover. We examined the characteristics of nest sites of American Wigeon (Mareca americana), Blue‐winged Teal (Spatula discors), Green‐winged Teal (Anas crecca), Mallards (Anas platyrhynchos), and Ring‐necked Ducks (Aythya collaris), and found differences among species that may facilitate species coexistence at a regional scale. Our results suggest that females of species nesting in upland habitat selected nest sites that optimized concealment from aerial predators while also allowing detection of and escape from terrestrial predators. Consequently, alteration in the composition and heterogeneity of vegetation and predator communities caused by climate change and industrial development in the boreal forest of Canada may affect the nest‐site selection strategies of boreal ducks.     

Plasticity of nest-site selection in the trumpeter finch: A comparison between two different habitats

In habitats with more predators, a species is expected to breed in safer sites and be less successful than in predator-impoverished habitats. We tested this hypothesis by studying nest-habitat selection and nest predation in two populations of Trumpeter finch (Bucanetes githagineus). One breeds in a predator-rich habitat (Tabernas, Iberian Peninsula), and the other is found on an island with fewer predators (La Oliva, Canary Islands). In both localities, we studied the features of nests in two different substrates, on the ground and in cliffs, including visibility and position in the cliff. We measured the habitat characteristics in a series of plots around the ground nests and compared them to random points. We also studied the influence of nest features and habitat selection on predation of both nest types. Trumpeter finches built more nests in cliffs in Tabernas, probably because there are more cliffs available there. In this locality, the patches selected for ground nesting had below-average vegetation cover, lower vegetation height, and were on steeper slopes. In La Oliva, they selected above-average vegetation height and steeper slopes. Cliff nests were less predated than ground nests in La Oliva, but not in Tabernas. The only variable that affected survival rates in Tabernas was the height of vegetation around ground nests, with nests in lower vegetation having higher survival rates. These results suggest that locality-related differences in habitat selection by vegetation height could be related to the different predator assemblages present in any given area, though we cannot rule out confounding influences of other differences between the two sites.     

Multiscale Nest-Site Selection by Black-Capped Vireos

Abstract: We used an information-theoretic approach to investigate nest-site selection by black-capped vireos (Vireo atricapilla) at the landscape and habitat-patch scales on Fort Hood Military Reservation in central Texas, USA, during 2003 and 2004. We used a use-availability sampling design and logistic regression to compare woody cover characteristics at nests to random points in the landscape to determine habitat selection at the landscape scale. At the habitat-patch scale, we used matched case-control logistic regression to compare habitat measures at nests and random non-nest points to evaluate support for hypotheses concerning the influence of woody cover, nest-patch, and nest-site characteristics on black-capped vireo nest-site selection. At the landscape scale, we found strong support (Akaike wt [w_j] = 1.0) for a model with a cubic effect of percent woody cover and woody cover edge density. Sites with the greatest predicted probabilities of use had woody cover values between 30% and 60% and increasing amounts of edge. We found strong support (w_i = 0.93) for the global model at the habitat-patch scale that included characteristics of the nest site, nest patch, and woody cover within 25 m. Based on odds ratios and confidence limits, percent woody cover, cover below 2 m, cover type, and substrate height had the greatest effect on nest-site selection. The predicted probability a site was selected for a nest site increased with foliage cover below 2 m, taller substrates, deciduous cover, and decreased at high levels of percent woody cover (especially >80%). Texas red oak (Quercus buckleyi) was the most used nest substrate (100 of 358 nests), followed by shin oak (Q. sinuata var. breviloba; 86 of 358 nests) and Ashe juniper (Juniperus ashei; 44 of 358 nests). Black-capped vireos used Texas red oak and shin oak in greater proportion to their availability, whereas Ashe juniper was used less in proportion to its availability, suggesting vireos avoided this species. We suggest that managers promote dense deciduous cover for nesting habitat and maximize edge-to-area ratios to maintain spatial and structural heterogeneity.     

Roost Structure,Modification, and Availability in the White‐throated Round‐eared Bat,Lophostoma silvicolum (Phyllostomidae) Living in Active Termite Nests1

We studied roost structure, modification, and availability in Lophostoma silvicolum (Phyllostomidae), an insectivorous gleaning bat, on Barro Colorado Island (BCI), Panamá. Collection of nest material beneath termitaria and infrared video filming indicated that males of L. silvicolum excavate and maintain cavities inside active termite nests. A binary logistic regression analysis showed that to be suitable as roosts, termite nests have to be larger than 30 cm in diameter and taller than 30 cm, well shaded, with few transecting branches, and freely accessible from below. Use of active termite nests as roosts may provide several benefits to L. silvicolum, including reduction of competition for roost sites with sympatric bat species, reduced parasite load and a suitable microclimate. A comparison of number of all termite nests in selected forest plots with number of termite nests that are potentially suited as bat roosts and number of termite nests that are actually used by bats suggests that L. silvicolum may not be roost‐limited on BCI in spite of its highly specialized roost choice.     

Nest site fidelity and dispersal of Rio Grande wild turkey hens in Texas

Rio Grande wild turkey (Meleagris gallopavo intermedia) nests suffer high predation rates exceeding 65%, which may limit recruitment. We evaluated post-nesting movements of reproductively active female Rio Grande wild turkeys. We monitored 194 nesting attempts between 2005 and 2010 and documented 17% and 32% overall apparent nest success for the Edwards Plateau and Central Rio Grande Plains study regions, respectively. Rio Grande wild turkey hens move approximately 1.2 km (SD = 0.7) between nesting attempts within a nesting season and approximately 1.4 km (SD = 1.6) between initial nesting attempts among years. Rio Grande wild turkey hens selected open areas with moderate woody cover for nesting ( = 37.7%; range = 3.0–88.2%). Patchiness of vegetation in the nesting landscape also was borne out by typically low edge-to-area ratios ( = 0.20; range = 0.040–0.732). We found no clear pattern in movement distance and either landscape composition or edge-to-area ratio for within or between breeding season nest site selection for either the Edwards Plateau or Central Rio Grande Plains study region. Based on our results, movement distances post-nest failure do not seem to influence habitat selection. © 2012 The Wildlife Society.     

Compounding effects of habitat fragmentation and predation on bird nests

Habitat fragmentation and invasive species are two of the greatest threats to species diversity worldwide. This is particularly relevant for oceanic islands with vulnerable endemics. Here, we examine how habitat fragmentation influences nest predation by Rattus spp. on cup‐nesting birds in Samoan forests. We determined models for predicting predation rates by Rattus on artificial nests at two scales: (i) the position of the bird's nest within the landscape (e.g. proximity to mixed crop plantations, distance to forest edge); and (ii) the microhabitat in the immediate vicinity of the nest (e.g. nest height, ground cover, slope). Nest cameras showed only one mammal predator, the black rat (Rattus rattus), predating artificial nests. The optimal model predicting nest predation rates by black rats included a landscape variable, proximity to plantations and a local nest site variable, the percentage of low (<15 cm) ground cover surrounding the nest tree. Predation rates were 22 ± 13% higher for nests in forest edges near mixed crop plantations than in edges without plantations. In contrast, predation rates did not vary significantly between edge habitat where the matrix did not contain plantations, and interior forest sites (>1 km from the edge). As ground cover reduced, nest predation rates increased. Waxtags containing either coconut or peanut butter were used as a second method for assessing nest predation. The rates at which these were chewed followed patterns similar to the predation of the artificial nests. Rural development in Samoa will increase the proportion of forest edge near plantations. Our results suggest that this will increase the proportion of forest birds that experience nest predation from black rats. Further research is required to determine if rat control is needed to maintain even interior forest sites populations of predator‐sensitive bird species on South Pacific islands.     

Herbaceous ground cover reduces nest predation in olive groves

Capsule Bare ground increases artificial nest predation in olive groves.

Aims To assess the effect of different soil management regimes on nest predation rates in olive groves.

Methods We performed nest predation experiments with artificial nests during the breeding season in 2013, in two areas of southern Spain. Each artificial nest (n?=?300) contained three quail Coturnix eggs, two of which were unmanipulated and the third one was emptied and injected with plaster. Predators were identified by marks on eggs filled with plaster.

Results Ground nests were significantly more depredated, irrespective of the presence of ground cover; tree nests were less depredated in fields with ground cover. There was a clear difference in nest predators of ground and tree nests. Rodents were the most frequent predators of tree nests.

Conclusion Lower predation rates of tree nests in orchards with ground cover are probably linked to a change in the foraging behaviour of rodents, which in these more complex habitats might be restricted by rodents' own risk of predation. This study underscores the important role of agricultural practices in preserving farmland bird communities, particularly tree-nesting species, suggesting that for this group, implementation of ground cover in olive groves might enhance breeding success by reducing nest predation rates.     

Opportunistic Predation of Wild Turkey Nests by Wild Pigs

Wild pigs (Sus scrofa; i.e., feral hogs, feral swine) are considered an invasive species in the United States. Where they occur, they damage agricultural crops and wildlife habitat. Wild pigs also depredate native wildlife, particularly ground-nesting bird species during nesting season. In areas inhabited by wild turkeys (Meleagris gallopavo), nest destruction caused by wild pigs may affect recruitment. There is debate whether wild pigs actively seek ground-nesting bird nests or depredate them opportunistically. To address this debate, in 2016 we examined the movements of wild pigs relative to artificial wild turkey nests (i.e., control [no artificial nests], moderate density [12.5–25 nests/km²], and high density [25–50 nests/km²]) throughout the nesting season (i.e., early, peak, and late) in south-central Texas, USA. We found no evidence that wild pigs learned to seek and depredate wild turkey nests relative to nest density or nesting periods. Despite wild pigs being important nest predators, depredation was not a functional response to a pulsed food resource and can only be associated with overlapping densities of wild pigs and nests. Protecting reproductive success of wild turkeys will require reducing wild pig densities in nesting habitat prior to nesting season. © 2019 The Wildlife Society.     

Precipitation and Reproduction are Negatively Associated with Female Turkey Survival

Understanding how reproductive tradeoffs act in concert with abiotic elements to affect survival is important for effective management and conservation of wildlife populations, particularly for at-risk or harvested species. Wild turkeys (Meleagris gallopavo) are a high-interest species for consumptive and non-consumptive uses, and female survival is a primary factor influencing turkey population dynamics. We radio-tracked and collected survival data on 140 female Merriam's wild turkeys (M. g. merriami) in the northern Black Hills, South Dakota, USA, 2016–2018. We developed and compared a set of candidate models to evaluate how nest incubation, brood rearing, and precipitation could be associated with female survival. Increased time spent incubating was associated with reduced female survival. Additionally, daily precipitation was associated with reduced survival of incubating females. Seasonal survival was lowest during spring and winter. A female that did not incubate a nest was predicted to have a higher rate of annual survival (0.53, 85% CI = 0.48–0.59) than a female that incubated a single nest (0.47, 85% CI = 0.42–0.53). Despite the relative proximity of population segments, we estimated that annual survival for nesting and non-nesting females was lower in the northern Black Hills compared to annual female survival in the southern Black Hills, underscoring the need for region-specific data when possible. © 2020 The Wildlife Society.