Nest Failure Research Articles

Effects of forest management practices, weather, and indices of nest predator abundance on nest predation: A 12-year artificial nest study

Nest predation is often the primary cause of avian nest failure, and factors influencing nest predation are diverse. To better understand how forest management practices, weather, and indices of nest predator abundance influence nest predation, we set artificial ground nests at 100 sites for 2weeks each summer from 2002 to 2013 in a longleaf pine/wiregrass ecosystem. We modeled effects of prescribed fire, hardwood removal, rainfall, temperature, indices of mammalian and avian nest predator abundance, and proximity to wildlife food plots and agriculture, edges, and roads on nest predation. Annual nest predation rates ranged from 30% to 74% and averaged 53%. Occurrence of prescribed fire at a nest site <2months prior to nest placement had a strong, positive association with nest predation but prescribed fires carried out >2months prior to nest placement had little effect. Hardwood removal was also associated with increased rates of nest predation, but this effect appeared most prevalent 4–9years following removals. Nest predation rates also increased when food plots or agricultural fields were within 50m of nest sites. Higher temperatures were associated with greater rates of predation, but rainfall did not have a significant influence. There was a general lack of support for effects of predator indices on nest predation rates, except for a weak, negative association with raccoon relative abundance. This study shows the wide range of factors which may influence nest predation and importance of viewing effects of forest management practices on nest predation over the long term.

NESTING OF THE SCRUB TANAGER (TANGARA VITRIOLINA) IN ANDEAN ECUADOR

The Scrub Tanager (Tangara vitriolina) occurs in dry inter-Andean valleys of Colombia and northern Ecuador. Even though it thrives in human-made habitats, knowledge about its breeding biology is scarce, with no complete description of its nest. In this paper, I present a detailed description of its nest, eggs, and nestlings, including notes on its breeding behavior. The nest is an open cup constructed with grass fibers, dry sticks, rootlets, plastic fibers, dry leaf litter and other vegetal material, spider web, and mammal hair. It was built near the tip of a hanging vine, supported below by three intertwined twigs, 2 m above ground. The female incubated whitish blue eggs speckled brown for 14–15 days. The male attended closely and brought food to the female several times. Nestlings were fed mostly by the female. The nesting pair did not attempt a second brood at this nest after failure; instead, they collected nesting material from this nest up to three days after nest failure.

Helper effects in the azure‐winged magpie Cyanopica cyana in relation to highly‐clumped nesting pattern and high frequency of conspecific nest‐raiding

In avian cooperative breeding systems, many benefits obtained by social pairs from the presence of helpers have been uncovered. However, until now, the factors that determine the type of assistance helpers provide and the responses of social pairs have not been well illustrated. We examined the contribution of helpers to cooperative groups and the relevant responses of dominant pairs in the azure‐winged magpie Cyanapica cyana which breeds on the Tibetan Plateau. We used the capture–mark–recapture method to identify helpers. Results showed that helpers were mostly the yearling sons of dominant pairs. They mainly contributed to the cooperative group in three ways, courtship‐feeding the incubation female, provisioning the brood, and defending the nest. For responses of dominant pairs, we unexpectedly found that clutch size was not influenced by the presence of helpers at the nest. However, cooperative groups had higher brood feeding rates than biparental nests and their feeding pattern also differed to that of the latter. Consequently, nestlings in cooperative groups had larger fledging body mass than that in biparental nests. By examining reasons for nest failure, we revealed that conspecific nest‐raiding contributed to more nest failure than any other natural predators. Because of the contribution of helpers in defending against both predators and conspecific nest‐raiders, cooperative groups had higher survival rate than biparental nests. Thus, our findings suggest that in a highly‐clumped nesting pattern, factors concerning the risk of nest predation, rather than that influencing food supply, play an important role in determining helper effects and responses of aided dominant pairs.

Molecular forensics in avian conservation: a DNA-based approach for identifying mammalian predators of ground-nesting birds and eggs.

BackgroundThe greater sage-grouse (Centrocercus urophasianus) is a ground-nesting bird from the Northern Rocky Mountains and a species at risk of extinction in in multiple U.S. states and Canada. Herein we report results from a proof of concept that mitochondrial and nuclear DNAs from mammalian predator saliva could be non-invasively collected from depredated greater sage-grouse eggshells and carcasses and used for predator species identification. Molecular forensic approaches have been applied to identify predators from depredated remains as one strategy to better understand predator–prey dynamics and guide management strategies. This can aid conservation efforts by correctly identifying predators most likely to impact threatened and endangered species. DNA isolated from non-invasive samples around nesting sites (e.g. fecal or hair samples) is one method that can increase the success and accuracy of predator species identification when compared to relying on nest remains alone.ResultsPredator saliva DNA was collected from depredated eggshells and carcasses using swabs. We sequenced two partial fragments of two mitochondrial genes and obtained microsatellite genotypes using canid specific primers for species and individual identification, respectively. Using this multilocus approach we were able to identify predators, at least down to family, from 11 out of 14 nests (79 %) and three out of seven carcasses (47 %). Predators detected most frequently were canids (86 %), while other taxa included rodents, a striped skunk, and cattle. We attempted to match the genotypes of individual coyotes obtained from eggshells and carcasses with those obtained from fecal samples and coyotes collected in the areas, but no genotype matches were found.ConclusionPredation is a main cause of nest failure in ground-nesting birds and can impact reproduction and recruitment. To inform predator management for ground-nesting bird conservation, accurate identification of predator species is necessary. Considering predation can have a high impact on recruitment, predation events are very difficult to observe, and predator species are difficult to identify visually from nest remains, molecular approaches that reduce the need to observe or handle animals offer an additional tool to better understand predator–prey dynamics at nesting sites.Electronic supplementary materialThe online version of this article (doi:10.1186/s13104-015-1797-1) contains supplementary material, which is available to authorized users.

Effect of supplementary feeding on reproductive success of hihi (stitchbird, Notiomystis cincta) at a mature forest reintroduction site

Supplementary feeding has proven to be a successful conservation tool for many species, including New Zealand’s hihi (stitchbird, Notiomystis cincta). Previous research has shown supplementary feeding to substantially increase hihi reproductive success at regenerating forest sites, but suggested that it would have reduced benefit in mature forest habitat. Here we report the first direct test of the effect of supplementary feeding on hihi reproductive success in mature forest, using data from the recently reintroduced population at Maungatautari Ecological Island. Eight feeder-using females and nine non-feeder-using females were monitored during the 2012/13 breeding season at Maungatautari to determine how feeder use affected reproductive success (nest success, number of first-clutch fledglings per female and total number of fledglings per female). Feeder-using females fledged 3.7 times as many fledglings as non-feeder-using females in their first-clutch attempts (95% CI 1.6–8.8), and 1.8 times as many fledglings in total (95% CI 1.0–3.5). No feeder-using female experienced nest failure, whereas 7 of the 16 nest attempts of non-feeder-using females failed to fledge any young. The results suggest that, counter to expectations, supplementary feeder use has a significant impact on reproductive success in mature forest habitat. At least for Maungatautari, providing supplementary food in mature forest habitat appears to greatly reduce the probability of hihi nest failure, and increases the number of young a female can fledge.

Breeding biology of the red-backed shrike, Lanius collurio, in the Kızılırmak Delta in the north of Turkey

The population trend of the red-backed shrike, Lanius collurio, is declining in its range. We studied the breeding biology of this species in the 2011 and 2012 breeding seasons in the north of Turkey. Our study site was an area of approximately 650 ha in the Kizilirmak Delta. Population density was 2.4 breeding pairs (bp)/10 ha and 2.7 bp/10 ha in 2011 and 2012, respectively. Blackberry bushes were used most frequently as nest sites (66%). The mean height of the nests from the ground was 125 ± 39 cm. The mean height of nest plants was 224 cm ± 76 cm. Nest height and nest plant height were positively correlated. We present an inequality of breeding parameters in the two successive breeding seasons. In 2011, the red-backed shrikes arrived at their breeding sites later, began to breed later, laid smaller clutches, and were less productive than in 2012. The main factor of the nest failures was nest predation in the study area. We detected normal second broods (six pairs) and it seems that this case was not exceptional. The Kizilirmak Delta is an important breeding area of the red-backed shrike population and more comprehensive studies are required.

A Low-Disturbance Capture Technique for Ground-Nesting Double-Crested Cormorants (Phalacrocorax auritus)

Abstract. Capturing breeding adults of colonially nesting species can entail risks of nest failure and even colony abandonment, especially in species that react strongly to human disturbance. A low-disturbance technique for capturing specific adult Double-crested Cormorants (Phalacrocorax auritus) at a ground-nesting colony was developed to reduce these risks and is described here. Nesting habitat enhancement was used to attract Doublecrested Cormorants to nest adjacent to above-ground tunnels constructed so that researchers could capture birds by hand. Using this technique, Double-crested Cormorants (n = 87) were captured during the incubation and chick-rearing stages of the nesting cycle. Unlike alternative capture techniques, this approach allowed targeting of specific individuals for capture and recapture, minimized local disturbance, and eliminated colony-wide disturbances. The tunnel-based system presented here could be adapted to capture adults or to access the nest contents of other ground-nesting...

Nesting success of native and introduced forest birds on the island of Kaua‘i

Forests of the Hawaiian archipelago are a global hotspot for conserving avian diversity and contain among the world's most imperiled species. Demographic studies are necessary to determine primary causes of Hawaiian forest bird population declines. We conducted research on the nesting success of multiple bird families on the island of Kaua‘i, allowing us to investigate the importance of factors related to breeding biology on forest bird declines at a community scale. Our study included two Hawaiian honeycreepers, ‘anianiau Magumma parva and ‘apapane Himatione sanguinea, a native monarch flycatcher, Kaua‘i ‘elepaio Chasiempis sclateri, and one introduced species, Japanese white‐eye Zosterops japonicus. Data from 123 nests showed that nesting success ± SE, estimated using program MARK, was low for ‘apapane (0.23 ± 0.10), but did not vary substantially among our other study species (‘anianiau = 0.56 ± 0.09, Kaua‘i ‘elepaio = 0.63 ± 0.08, Japanese white‐eye = 0.52 ± 0.11). Causes of nest loss for 51 nest failures included nest predation (43%), unknown (25%), empty after termination with no signs of nest predation (e.g. eggshell or chick remains in nest, disheveled nest) (24%), and abandoned clutch or brood (4% each). Kaua‘i ‘elepaio suffered more than twice as many nest losses to predation compared to our other study species, but also had the highest nesting success; and, ‘apapane suffered least to nest predation, but had the lowest nesting success. Further, rates of nesting success derived in our study were relatively high compared to multi‐species studies in mainland tropics. Therefore, although nest predation accounted for the greatest proportion of nest failures, it may not be a cause of forest bird population declines in our system. We suggest that future demographic studies focus on post‐fledgling, juvenile, and adult survival, in addition to the importance of double‐brooding and renesting attempts on annual reproductive success.

Breeding biology of the European Blackbird Turdus merula in orange orchards

During two successive years (2013–2014), we studied the breeding ecology of the European Blackbird Turdus merula in Guelma province, north-east of Algeria. The study was carried out in orange orchards of the region. We investigated nest placement in the orange trees and determined the factors of reproductive failure at this study area. Nests were placed at low height (mean±SD=1.42±0.04m) and located near the trunk (mean±SD=0.61±0.04m). The breeding season occurred between mid-May and mid-June and the peak of egg laying took place during the first half of May. The mean clutch size was 2.96±0.05, density of breeding pairs was 0.83±0.30p/ha. The breeding success reported in the present study was higher than that recorded in other studies. Predation was the leading cause of nest failure of the population under investigation. The present study shows that the orange orchards appear to be the preferred breeding area for Blackbird population.

Nesting ecology of Ferruginous Duck Aythya nyroca in north-eastern Algeria

The status of waterbirds breeding in protected areas in North Africa needs constant monitoring because of a naturally fluctuating environment and permissive attitudes towards illegal activities likely to negatively affect population dynamics of threatened species. We present the results of a study conducted at a protected site, Lake Tonga, north-eastern Algeria, on a breeding population of Ferruginous Duck Aythya nyroca, a Near-Threatened duck subjected to considerable pressure from egg-pilfering and illegal hunting. Two distinct habitats within the lake were used by Ferruginous Duck: an Alder carr (Alnus glutinosa) and floating islets across the lake. The mean clutch size was 9.51±1.84 eggs (N = 51 clutches) with hatching rate of 80.7% for successful clutches. Breeding success was low (37%) with predation (33%) and clutch desertion (17%) accounting for the majority of failed nests. The probabilities of nest failure and nest desertion increased with a delayed onset of egg laying. Predation was not significantly associated with egg laying date and vegetation cover, but late breeders nesting in dense vegetation seemed to suffer less predation. Conspecific brood parasitism was positively associated with nest size, whereas interspecific brood parasitism was marginally associated with water depth. We discuss different hypotheses concerning nest desertion, and argue that illegal hunting and disturbance may best explain why birds desert their nests.

Breeding success of the Great Tit Parus major in relation to attributes of natural nest cavities in a primeval forest

An overlap in attributes of nest cavities used by Great Tit Parus major across Eurasia suggests similar nest site preferences within the geographical range, although the drivers of these preferences are unclear. To determine whether preferred cavities provide conditions enhancing successful reproduction, we investigated the breeding performance of Great Tits in relation to tree cavity characteristics using data collected during 2008–2011 in primeval conditions (Bialowieza National Park, Poland). Here, tree cavities are diverse and superabundant but nesting birds are at risk from a variety of predators. According to expectations, nest losses were high (60 % of Great Tit nests failed), mostly due to predation (69 % of nest failures). The risk of nest failure varied with nest cavity attributes. Compared to successful nests, failures were situated higher above the ground and placed closer to the cavity entrance. Very deep cavities with narrow entrances and strong livings walls provided effective protection against larger predators (e.g., martens, woodpeckers), unable to enter the cavity or pull out the contents. Yet, such holes were no barrier for the smallest predators (e.g., Forest Dormouse Dryomys nitedula), which were able to enter any Great Tit nest cavity and destroyed most of the nests. Avoiding small predators would give a selective advantage to the birds, but this seems hardly possible to achieve. We conclude that tree cavities preferred by the tits show a combination of properties which are a compromise for avoiding predation (the strongest selective pressure) and providing the minimum requirements (sufficient nest illumination, microclimate, protection against nest soaking) for development and growth of young.

Predator identity influences the effect of habitat management on nest predation.

Predation is the leading cause of nest failure for many passerines and considerable effort is devoted to identifying the habitat characteristics and management practices that influence nest loss. The habitat components associated with nest loss are strongly influenced by the ecology of nest predators and differ among predator species as a result. Nevertheless, there is a tendency to generalize about the effects of habitat features and management on nest failure without considering how resulting patterns are influenced by nest predators. We examined how predator-specific patterns of nest loss differed among predators and in response to grassland management with fire and grazing by cattle (Bos taurus). We used video cameras to monitor and identify predators at nests of the Grasshopper Sparrow (Ammodramus savannarum), a species of conservation concern throughout its range. We observed predation by 15 different species that differed in their response to management and the habitat characteristics associated with nests they preyed on. Losses to mammals and snakes were more likely at nests with greater amounts of litter cover and tall fescue (Schedonorus phoenix). Mammals were less likely to prey on nests surrounded by greater forb cover. Nest predation by snakes was lower in burned areas, whereas predation by mammals and Brown-headed Cowbirds (Molothrus ater) was unaffected by the use of fire. Neither vegetation density at the nest, nor landscape context was related to nest loss by any predator taxon. Although there were many similarities, we identified important differences in the species composing the nest predator community between our. study and other published research. These differences are likely to be responsible for geographic variation in the influence of habitat features and management actions on nest success. Our results demonstrate the need for natural resource managers to incorporate knowledge of local nest predators and their ecology when developing management prescriptions aimed at enhancing the reproductive success of songbirds.

Breeding biology and nest survival in Tropical Screech-Owls (Megascops choliba) in the Brazilian Cerrado

Different ecological parameters are associated with the selection of nests and breeding sites in birds. Understanding nest-site selection and the subsequent consequences for reproductive success are critical to a full understanding of how natural selection shapes birds’ nesting behavior. Between 2007 and 2008, we evaluated nest-site characteristics and nesting success of Tropical Screech-Owls (Megascops choliba) in an area of Cerrado interspersed with cultivated areas in central Brazil. We compared the characteristics of cavities used for nesting by owls and unused nesting cavities and modeled nest survival in MARK. Models were assessed using Akaike’s Information Criterion for small sample sizes (AICc) and model averaging was used to infer model parameters. Tropical Screech-Owls nested in tree and termite-mound cavities. Nest success was 44.4%, with predation being the main cause of nest failure. We found that Tropical Screech-Owls nested in cavities with different orientations, and closer to the ground than unused cavities. Although the top-ranked models included nest height and nest concealment, multimodel inference showed that these variables had no clear effect on nest survival. Despite the lack of effect of these variables on nest survival, nest-site characteristics commonly associated with a cavity’s microclimate (i.e., orientation of cavity entrance) may still have a stronger influence on nest-site selection.

Do fluctuating water levels alter nest survivorship in reservoir shrubs?

Reservoirs often have highly fluctuating water levels. The perimeters of these impoundments, which alternate between being exposed or inundated by water (drawdown zone), are used by nesting birds, but at the risk of nest submergence when water levels rise. For species that nest above the ground in shrubs, foraging and predation may also be affected by flooded habitat. Our objective was to clarify the net impact that habitat flooding has on nest survivorship at Arrow Lakes Reservoir, British Columbia, Canada. This reservoir typically shows a pattern of water management where water is stored during the spring snowmelt (increasing water levels) and released later in the year. Yellow Warblers (Setophaga petechia; n = 272 nests) and Willow Flycatchers (Empidonax traillii; n = 81 nests) nested in similar parts of the drawdown zone, but differences in their nesting behaviors, particularly timing of nesting, caused the flycatchers to experience more nest submergence. Flycatchers also nested on a floating island of bog habitat, offering them some protection from nest submergence. We found little evidence that drawdown zone shrubs functioned as ecological traps. In flooded conditions, 28% of warbler nests failed due to submergence. Warbler nest daily survival rate (DSR) declined with advancing ordinal date, and we concluded that their DSR was not influenced by habitat flooding. For flycatchers, 50% of nest failures were caused by submergence under flooded conditions, but DSR did not differ between flooded (0.960 ± 0.009) and unflooded conditions (0.958 ± 0.012). We speculate that these counterintuitive results may be explained by a reduction in predation levels during flooded conditions, which may compensate for nest submergence. Finally, we found that nest DSR was enhanced in the floating island habitat (0.986 ± 0.005), indicating that floating habitat islands can be highly productive and may hold potential as a management tool for enhancing productivity of reservoir drawdown zones.

Factors affecting nesting success in the Great-crested Grebe Podiceps cristatus at Lake Tonga, north-east Algeria

The breeding ecology of the Great-crested Grebe Podiceps cristatus was investigated over four consecutive years (2009-2012) at Lake Tonga, north-east Algeria. In all four years, the egg-laying period was relatively short, spanning two months (end of March to end of May), and bimodal. Nests were mainly located in Phragmites australis, over water of substantial depth (178 ± 43 cm, N=209), far from the shore and in habitat with low vegetation cover (12.37 ± 7.67%, N=209). The overall clutch size was 3.73 ± 0.92 eggs (N=127) and it decreased marginally over time. The overall nesting success was 70.4% (N=209), with nest failure caused mainly by predation (65%) and flooding (23%). Breeding outcome was significantly and positively related to nest size, with bigger nests conferring better survival to eggs and young probably through affording better protection during spells of adverse weather. However, the benefits of bigger nests may be confounded by the age or intrinsic quality of birds. The location of nests in P. australis, rather than other vegetation types, increased nesting success marginally but significantly. Two cases of interspecific mixed clutches involving the Great-crested Grebe were recorded.

Reproductive Performance of a Declining Forest Passerine in Relation to Environmental and Social Factors: Implications for Species Conservation.

Identifying factors influencing a species' ecological niche and demography is a prerequisite for species conservation. However, our understanding of the interplay between demographic rates and biotic/abiotic factors is still poor for most species of conservation concern. We evaluated relevance of eight hypotheses relating to timing of breeding, temporal nest exposure, nest concealment, topography, tree structure, predation risk and disturbance, density dependence and weather for explaining variation in reproductive performance of the declining wood warbler Phylloscopus sibilatrix in northern Switzerland. Reproductive performance was monitored with cameras at 136 nests from 2010 to 2012 and was associated to temporal exposure, timing of breeding and concealment of nests. Daily nest survival was positively related to the number of grass and sedge tussocks, nest concealment and nest age. Clutch size and number of fledglings decreased, the later in the season a nest was initiated. Nest survival over an average nesting period of 31 days was 46.9 ± 0.07% (mean ± SE), daily nest survival rate was 0.976 ± 0.002. As for many ground-breeding birds, nest predation was the principal cause of nest failure, accounting for 79% of all nest losses. Conservation measures should aim at increasing the area of relatively homogenous forest stands featuring suitable habitats characterized by abundant and accessible grass and sedge tussocks. In managed forests, such conditions can be found in stands of middle age (i.e. pole wood) with little to no shrub layer.

Nest Failure Owing to Intraspecific Agonistic Behaviour in Dupont's LarkChersophilus duponti

Abstract Intraspecific nest aggression in a diverse array of passerine species is usually explained in the context of competition for nesting sites among cavity nesters, or as parental investment among polygynous species, but has been reported only rarely in monogamous, open ground-nesting species such as larks. We video-monitored ten Dupont's Lark nests. This declining species has a patchy and restricted distribution in Iberia and northern Africa. We detected aggression toward one nest, during which a female deserted her clutch after being attacked by another Dupont's Lark. This is the first record of nest abandonment resulting from intraspecific agonistic behaviour in the Alaudidae family. The high density and proximity of territories of Dupont’s Lark in the study area seems a likely explanation for such agonistic behaviour, which may be a neglected cause of nest failure in shrinking Dupont’s Lark populations living in small habitat patches.

Reproductive Success of Colonial Tree-nesting Waterbirds in Prairie Pothole Wetlands and Rivers throughout Northeastern South Dakota

The northern Great Plains of North America provides critical breeding habitat for many colonial tree-nesting waterbirds, but reproductive success and population parameters for these species are largely unknown within the Prairie Pothole Region, specifically in South Dakota. The objective of this study was to evaluate reproductive success of colonial tree-nesting waterbirds on selected wetlands and rivers in northeast South Dakota. During the 2008 and 2009 breeding seasons, nesting and fledging success of Black-crowned Night-Heron (Nycticorax nycticorax), Great Blue Heron (Ardea herodias), Cattle Egret (Bubulcus ibis), Great Egret (A. alba), Snowy Egret (Egretta thula), and Double-crested Cormorant (Phalacrocorax auritus) were estimated in 39 individual colonies. A total of 2551 individual nests were monitored from 15 Apr. - 15 Aug. in 2008 and 2009. Overall apparent nest and fledge success (respectively) were: Black-crowned Night-Heron (52.1%, 47.9%), Great Blue Heron (58.2%, 35.9%), Cattle Egret (73.1%, 69.2%), Great Egret (61.5%, 50.7%), Snowy Egret (83.6%, 81.7%), and Double-crested Cormorant (70.4%, 54.2%). Nest abandonment accounted for an average of 47.6% of nest failures for all species combined. Nest structure failure and young dying within nests accounted for most failures to fledge. Nesting success increased with the area of wetland habitat in the landscape for all species analyzed. Lower reproductive success of Black-crowned Night-Heron and Great Blue Heron, compared to other findings across the U.S. and Canada, suggests that these breeding populations in northeast South Dakota may be declining. Cattle Egret, Great Egret, Snowy Egret, and Double-crested Cormorant reproductive success is relatively high in northeast South Dakota compared to other North American populations. Preserving and restoring wetland habitat surrounding waterbird colonies will provide successful nesting habitat as well as foraging areas and opportunities for new colony site locations.

Indirect effect of climate change: Shifts in ratsnake behavior alter intensity and timing of avian nest predation

Understanding how climate change will affect the abundance, distribution, and behavior of wildlife has garnered substantial attention, but predicting how climate change may alter interspecific relationships is more challenging and has received less attention. Here, we use agent-based modeling to explore how climate warming may alter activity patterns and habitat use of ratsnakes and how this will change their interactions with nesting birds. Overall nest predation by ratsnakes increased with warming environmental temperatures, with a 7% increase in daily nest predation as temperatures warmed by 2°C. Modest increases in ambient temperature (0.5°C) caused nocturnal predation by ratsnakes to increase by 15%, particularly in the early spring (200% increase in nocturnal nest predation in March) when nocturnal snake activity is currently limited. Increased nocturnal nest predation can have important demographic consequences beyond nest failure when adult birds on the nest are vulnerable to snakes. Increased temperatures also caused nest predation to increase substantially in forest and forest edge habitats. In a warming world ratsnakes are predicted to use forested habitats more because the thermal heterogeneity of forests buffers snakes against potentially lethal environmental temperatures. If ratsnakes become more concentrated in small forest patches and edges, nest survival in these patches may fall below a sustainable level. Conversely, as temperatures increase, ratsnakes will be less likely to prey on nests in open habitats such as shrublands, which may provide refuges for some nesting birds. Species conservation in a warming world requires understanding how the behavior of both the focal species and its predators are affected.

Breeding biology of sympatric LaughingStreptopelia senegalensisand TurtleStreptopelia turturDove: a comparative study in northeast Algeria

The Turtle Dove and Laughing Dove display distinct behavior and are morphologically and genetically different. However, microhabitat selection and reproductive success details of the two species are still poorly studied. The geographic distribution of the Laughing Dove in North Africa has clearly expanded nowadays. The breeding ecology and nest placement of this species have been studied previously, but little is currently known about its life history in Algeria. This study aimed to provide the basic information on the breeding biology of the Laughing Dove in Algeria. During two consecutive breeding seasons (2013–2014), the clutch size, brood size, chick survival, timing of breeding, densities of breeding pairs, nest placement, and the main causes of nest failure of the sympatric Laughing Dove and Turtle Dove were studied in an olive orchard in Guelma region, northeast Algeria. Clutch size, brood size, chick survival, the estimated productivity, and nest placement of the two species were similar but timin...