Predation Rates Of Artificial Nests Research Articles

Nesting success and potential nest predators of the red Junglefowl (Gallus gallus jabouillei) based on camera traps and artificial nest experiments

Breeding success is an important factor determining fecundity with nest predation being the main factor limiting avian breeding success. Understanding of nest predation and its influencing factors are highly significant to explore the dynamics of bird populations and developing appropriate conservation strategies. In two breeding seasons of the year 2020 and 2021, natural nests of the red junglefowl (Gallus gallus jabouillei) were systematically searched and monitored using infrared camera, in two nature reserves (Datian and Bangxi) of tropical Hainan island, China. Results showed that breeding season of the red junglefowl is mainly from March to July, with April being the breeding peak. The clutch size was 5.15 ± 1.28 (n = 13), and nesting success of natural nests was 31.2%, with nest predation accounting for 45.4% of nest failure. Artificial nest experiments showed that predation rates of artificial nests were 25% (Datian, 2020), 6.67% (Datian, 2021), and 0% (Bangxi, 2020). Rodents, reptiles, and coucals are the main nest predators of red junglefowls, while activities of Hainan Eld’s deers (Panolia siamensis) may interfere with the reproduction of red junglefowls. We suggest that the conservation management policies should consider the impacts on junglefowls’ breeding success when reconstructing the suitable habitat of the Hainan Eld’s deer.

Bird eggs or wheat: Assessing the impact of an overabundant crow species in a landscape mosaic in the Negev desert of Israel

The intensification of land alterations promotes the spread of invasive and overabundant species. Yet, controlling such species is not always derived from extensive impact assessments. We explored the consequences of the Hooded Crow (Corvus cornix) expansion into the arid region of Israel on the local biota. Crow activities and their potential effects were examined in a nature reserve and its surrounding agricultural lands. We used line transect counts and Global Positioning System (GPS) tagging to assess crow habitat utilization patterns. To measure crow impact on the local community, we compared artificial nest predation rates between agrarian and natural land types. Compositional analysis of the GPS-tagged crows' home range indicated a preference for arable lands, with low utilization of natural areas, limited to the vicinity of the nature reserve edges. Accordingly, Hooded Crows were among the dominant nest predators, mainly in agricultural lands or near their borders. These findings suggest that crow impact on natural habitats is low and limited to highly exploratory individuals. As crow abundance is expected to continue increasing, we call for short and long-term management actions, including establishing agri-environmental schemes to boost the local community's resistance to overabundant and invasive species.

What habitat parameters are important for the survival of ground nests in mountain forests? Recommendations for protection of Hazel Grouse Tetrastes bonasia based on an experiment with artificial nests

ABSTRACT Capsule Predation risk of artificial nests resembling Hazel Grouse Tetrastes bonasia nests was reduced in more diverse habitats and when roads and trails were closer. Aims To determine the importance of habitat structure and the presence of roads and hiking trails for the predation risk of artificial ground nests. Methods We investigated predation on artificial nests in mountain spruce forests with high tourist numbers in the Tatra Mountains, Southern Poland, in 2012–2014. Some 174 artificial ground nests resembling those of Hazel Grouse were set up and monitored. For 98 artificial nests, we compared environmental variables at two area scales, and the forest structure between predated and surviving nests. Results At the local scale (within 5 m) artificial nests were more likely to be predated at sites with lower occurrence of ferns and lying dead wood. At the wider spatial scale (within 100 m), nests were more likely to survive if near to roads and tourist trails. The occurrence of different tree species in the forest stand did not significantly influence predation rate of artificial nests. The mean daily nest predation rate was not high and varied between years (0.003–0.009). Conclusion Greater habitat diversity and the presence of roads and trails increased the survival of ground nests. These results are potentially important for conservation planning for threatened ground-nesting birds, such as the Tetraonidae.

Testing Whether Camera Presence Influences Habitat Specific Predation Pressure on Artificial Shorebird Nests in the Arctic

When monitoring the breeding ecology of birds, the causes and times of nest failure can be difficult to determine. Cameras placed near nests allow for accurate monitoring of nest fate, but their presence may increase the risk of predation by attracting predators, leading to biased results. The relative influence of cameras on nest predation risk may also depend on habitat because predator numbers or behaviour can change in response to the availability or accessibility of nests. We evaluated the impact of camera presence on the predation rate of artificial nests placed within mesic tundra habitats used by Arctic-breeding shorebirds. We deployed 94 artificial nests, half with cameras and half without, during the shorebird-nesting season of 2015 in the East Bay Migratory Bird Sanctuary, Nunavut. Artificial nests were distributed evenly across sedge meadow and supratidal habitats typically used by nesting shorebirds. We used the Cox proportional hazards model to assess differential nest survival in relation to camera presence, habitat type, placement date, and all potential interactions. Artificial nests with cameras did not experience higher predation risk than those without cameras. Predation risk of artificial nests was related to an interaction between habitat type and placement date. Nests deployed in sedge meadows and in supratidal habitats later in the season were subject to a higher risk of predation than those deployed in supratidal habitats early in the season. These differences in predation risk are likely driven by the foraging behaviour of Arctic fox (Vulpes lagopus), a species that accounted for 81% of observed predation events in this study. Arctic fox prey primarily on Arvicoline prey and goose eggs at this site and take shorebird nests opportunistically, perhaps more often later in the season when their preferred prey becomes scarcer. This study demonstrates that, at this site, cameras used for nest monitoring do not influence predation risk. Evaluating the impact of cameras on predation risk is critical prior to their use, as individual study areas may differ in terms of predator species and behaviour.

Evaluation of Spatio-Temporal Patterns of Predation Risk to Forest Grouse Nests in the Central European Mountain Regions.

Simple SummaryForest grouses are among the most endangered ground-nesting birds in Central Europe. Their rapid population decline was associated with habitat loss and increasing predation risk leading to low breeding success. The aim of this study was to describe black grouse nest predators and potential predation risk in a study area with a small, extant population of black grouse (Ore Mts.) and in a study area with an already extinct grouse population (Jeseníky Mts.) in the Czech Republic. In order to determine the predation intensity to black grouse nests, 50 artificial nests (28 in Ore Mts., 22 in Jeseníky Mts.) were monitored using camera traps. The results showed that 56% of nests were predated. Within the time needed for successful incubation of the eggs (25 days), the nest survival probability was on average 45.5%. The proportion of depredated nests did not differ between habitat types (i.e., open forest interior, clearing, forest edge). The stone marten was the main potential nest predator in both study areas (39% in total), followed by common raven (25%) and red fox (22%). In conclusion, our study revealed the high predation pressure on black grouse nests which corresponds with increasing population trends of mesopredators and wild boars in Central Europe.We evaluated the spatiotemporal patterns of predation risk on black grouse nests using artificial nests that were monitored by camera traps in mountain areas with a small extant (Ore Mts.) and already extinct (Jeseníky Mts.) black grouse population. The overall predation rate of artificial nests was 56% and we found significant differences in survival rate courses over time between both study areas (68% Ore Mts. vs. 41%, Jeseníky Mts.). Within the time required for successful egg incubation (25 days), nest survival probability was 0.32 in the Ore Mts. and 0.59 in Jeseníky Mts. The stone marten (Martes foina) was the primary nest predator in both study areas (39% in total), followed by common raven (Corvus corax, 25%) and red fox (Vulpes vulpes, 22%). The proportion of depredated nests did not differ between habitat types (i.e., open forest interior, clearing, forest edge), but we recorded the effect of interaction of study area and habitat. In Ore Mts., the main nest predator was common raven with seven records (37%). The Eurasian jay (Garrulus glandarius) was responsible for most predation attempts in Jeseníky Mts. (five records, i.e., 83%), while in the Ore Mts., most predation attempts were done by red fox (six records, i.e., 38%).

Revisiting an old question: Which predators eat eggs of ground-nesting birds in farmland landscapes?

Nest predation is a major cause of reproductive failure in birds, but predator identity often remains unknown. Additionally, although corvids are considered major nest predators in farmland landscapes, whether breeders or floaters are involved remains contentious. In this study, we aimed to identify nest predators using artificial nests, and test whether territorial or non-breeders carrion crow (Corvus corone) and Eurasian magpie (Pica pica) were most likely involved. We set up an experiment with artificial ground nests (n = 1429) in farmland landscapes of western France, and assessed how different combinations of egg size and egg material (small plasticine egg, large plasticine egg, quail and natural hen eggs) might influence predation rates and predator species involved. Nest predators were identified using remotely triggered cameras and marks left in plasticine eggs. Corvids were by far the predators most involved (almost 80% of all predation events), independent of egg type. Carrion crows alone were involved in 60% of cases. Probability of predation increased with egg size, and predation rate was higher for natural than for artificial eggs, suggesting that, in addition to egg size, predators might perceive plasticine and natural eggs differently. Predation rates of artificial nests by corvids were related significantly to corvid abundance, and far more to breeder than floater abundances, for both carrion crows and magpies. This study emphasizes the importance of identifying predators at species level, and considering their social status when assessing corvid abundance impact on prey population dynamics. Combining camera traps and plasticine eggs can achieve this objective. Given the high predation rate by carrion crows, a better understanding of landscape-mediated changes in predator diet seems mandatory to design mitigation schemes able to confront ecological challenges raised by generalist predators.

High tourism activity alters the spatial distribution of Hazel Grouse (Tetrastes bonasia) and predation on artificial nests in a high-mountain habitat

Human presence can significantly reduce habitat availability for wildlife. We investigated the impact of the distance from hiking trails and number of tourists on the number of sites occupied by Hazel Grouse (Tetrastes bonasia) and on the predation rate of artificial nests in two forest types (spruce and beech) in the Tatra Mountains (Poland). The study was carried out in the Tatra National Park from 2009 to 2014. Presence of Hazel Grouse males was detected in spring by playing territorial calls of this species from an electronic device. A total of 79 sites occupied by Hazel Grouse were found, and 174 artificial ground nests were monitored. Data on the number of tourists gathered at entry points and at trail crossings in the Tatra National Park were used to estimate levels of tourism activity. Sites occupied by Hazel Grouse were mostly located farther from hiking trails and in places with low tourist numbers. Artificial nests were mainly predated by mammals (85%) in both spruce and beech forests.

An experimental test of a compensatory nest predation model following lethal control of an overabundant native species

Culling of overabundant and invasive species to manage their ecological impacts on target species is widely practised but outcomes are unpredictable and monitoring of effectiveness often poor. Culling must improve ecosystem function, so clear, measurable goals, such as improved breeding potential of target species, are necessary. Many overabundant and invasive species are also nest predators and nest predation is the principal cause of breeding failure of many birds of conservation concern. It is important for managers to know the likely effects on nest predation when culling one species among a suite of nest predatory species.We tested the effect of culling a hyperaggressive, overabundant bird and known nesting disruptor, the noisy miner (Manorina melanocephala), on artificial nest predation rates in remnant eucalypt woodlands in a highly fragmented agricultural landscape of eastern Australia. Culling of noisy miners is already practised to manage this key threatening process, but evidence of improved breeding outcomes for target species is lacking.We found no significant change in artificial nest predation rates following the treatment, despite a 28% reduction in noisy miner abundance in treatment compared to control sites. We identified five other nest predatory bird species, the noisy miner being responsible for 18.3% of total predation.Our findings suggest a compensatory nest predation model, which is problematic for management. It means that, where culling is done with a view to improving breeding potential of target species by reducing nest predation, removing one nest predatory species may not result in a commensurate reduction in nest predation.

Agroforestry system as a buffer zone in a Brazilian Atlantic Forest conservation unit: an artificial nest predation perspective

Abstract Here we inferred about the effectiveness of a buffer zone composed by an Agroforestry System (AS) for providing reproductive conditions for Atlantic Forest birds by comparing artificial nest predation rates between a buffer zone, a primary forest area, and a set of small and isolated Atlantic Forest fragments. We have used 237 nests throughout the three areas, of which 100 (42.2%) were depredated. Predation frequencies were 28.6% in the continuous forest, 100% in the AS, and 51.9% in the fragments, differing significantly. We could detect nest predators in 48 of the 100 depredated nests (48%) using camera traps. Differences between areas may be attributed to changes in nest predator species. We support previous evidences that the conservation of bird communities may not rely on buffer zones as an extension of their breeding habitats.

Nest site preferences of the Woodlark (Lullula arborea) and its association with artificial nest predation

The Woodlark is an insectivorous bird, which is listed as a priority species in Switzerland. In Valais, a stronghold of this species in the country, the birds breed in intensively managed vineyards and show a preference for parcels with ground vegetation during territory establishment. As a ground-breeder, the species is highly vulnerable to nest predation by avian and mammal predators. The aims of our study were firstly to investigate nest site preferences of the woodlark within vineyards and secondly to compare the predation risk of artificial nests dependent of ground vegetation structure. Our results point out that the Woodlark prefers patches of tall and dense ground cover within vegetated vineyard parcels and avoids parcels that have been treated with herbicides. In a follow-up experiment we conducted a study comparing the predation rate of artificial nests between bare parcels (<20% vegetated area) and vegetated parcels (>40% vegetated area). Artificial nests equipped with one quail egg were distributed pairwise between two adjacent parcels that fulfilled the upper criteria and were monitored by trail cameras during 10–12 days. Predation rate was generally low (4 predation events) and only occurred in bare parcels. These data indicate that conspicuousness of avian nests may be decreased in vegetated parcels and that the amount of vegetation can lower the predation risk on ground breeding birds - another indication for the importance of ground vegetation for a successful conservation of the endangered Woodlark in Swiss vineyards.

The effect of treeline proximity on predation pressure: an experiment with artificial nests along elevational gradients in the European Alps

ABSTRACTCapsule: Predation rates of artificial nests along elevational gradients were higher closer to the treeline in the European Alps.Aims: Alpine grassland birds tend to show an avoidance of mature trees, possibly due to an edge effect, such as higher predation pressure close to the treeline. This study aimed to estimate potential predation pressure in relation to the distance from the treeline and other environmental variables by using artificial nests positioned along elevational transects in the Italian Alps.Methods: A total of 119 artificial nests were positioned and monitored during the breeding season. For each nest, habitat data at small and large scales were collected. Daily nest survival was estimated using MARK.Results: The most informative model included date, distance from the treeline and a micro-habitat structure variable. In particular, the model showed a positive relationship between nest survival and the distance from the treeline.Conclusions: This study suggests that if treelines advance due to climate change, the functional habitat loss may be greater than physical habitat loss, since the optimal breeding area would be further away from the forest edge. The conservation of high-elevation grasslands in relation to environmental changes may therefore be addressed through management strategies to maintain open habitats.

Reed Parrotbill nest predation by tidal mudflat crabs: Evidence for an ecological trap?

Understanding the relationships between nesting habitat quality and predation risk is essential for developing appropriate conservation management for threatened species. This is particularly relevant where anthropogenic pressures could decouple the environmental cues used by birds to assess nesting habitat quality from increased predation risk. In this study, we conducted a series of surveys and nest experiments to examine the nest predation rates of Reed Parrotbill (Paradoxornis heudei) a passerine bird between inland and tidal reed‐bed wetland habitats, at Yellow River Delta National Nature Reserve, Eastern China during 2008, and 2010–2012. We found significant differences in the habitat structural characteristics between the two adjacent wetland habitats that are critical for Reed Parrotbill nest‐site selection. Experimental trials using recently constructed and abandoned Reed Parrotbill nests as ‘artificial nests, quail eggs and predator‐exclusion measures, revealed that tidal mudflat crab (Helice tientsinensis) was the primary cause of Reed Parrotbill egg predation in tidal reed‐bed habitat. Annual predation rates of real nests from inland reed‐bed habitat varied from 35% to 68%, and predation rates of artificial nests were much lower than those from real nests. Pitfall sampling revealed that the abundance of tidal mudflat crabs was significantly higher in tidal reed‐bed habitat. Our data suggested that Reed Parrotbills breeding in tidal reed‐bed habitats may be highly vulnerable due to extremely high rates of nest predation (up to 100%), caused primarily by the high density of tidal mudflat crabs. The incongruence between nest‐site habitat preference and nest survival indicated an ecological trap scenario, which requires further studies on its proximate and ultimate causes as well as the development of effective conservation management for the Reed Parrotbill.

Artificial nest predation rates vary depending on visibility in the eastern Brazilian Amazon

Observational and experimental studies have shown that increased concealment of bird nests reduces nest predation rates. The objective of the present study was to evaluate differences in predation rates between two experimental manipulations of artificial ground nests (i.e., clearing an area around the artificial nest or leaving it as natural as possible), and test whether environmental variables also affected nest predation in an undisturbed area of Amazonian forest in eastern Brazil. A generalized linear model was used to examine the influence of five variables (manipulation type, perpendicular distance from the main trail, total basal area of trees surrounding the nest site, understorey density, and liana quantity) on nest predation rates. Model results, showed that manipulation type was the only variable that significantly affected nest predation rates. Thus, to avoid systematic biases, the influence of nest site manipulation must be taken into consideration when conducting experiments with artificial nests.

Nest position and type affect predation rates of artificial avian nests in the tropical lowland forest on Mount Cameroon

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.

The use and function of snake skins in the nests of Great Reed Warblers Acrocephalus arundinaceus

We documented and experimentally tested the use of snake skins in construction of nests in a Great Reed Warbler Acrocephalus arundinaceus population in southwestern Slovakia. There was no difference in predation rates of artificial nests that did or did not contain sloughs. We suggest that snake skins in Great Reed Warbler nests may serve as a post-pairing signal revealing female parental quality.

Artificial nest predation rates vary among habitats in the Australian monsoon tropics

AbstractRates of nest predation have frequently been shown to differ between fragmented and unfragmented habitats, but have rarely been compared among natural habitats in the same geographic region. In this study, artificial nests of two types (open cup and domed) were placed in four habitats (mangroves, monsoon rainforests, eucalypt woodlands and paperbark swamps) over 12 months in three localities near Darwin in the Australian monsoon tropics to determine the effects of habitat, season and nest type on the rate of nest predation. A quail egg and a similarly coloured plasticine egg were placed in each nest. Habitat had a strong effect on nest predation rates, with nests in mangroves experiencing predation rates more than four times higher than those in eucalypt woodlands and paperbark swamps. Despite the strong rainfall seasonality of the region, there was no consistent seasonal variation in nest predation rates. Nest type also had little influence on predation rates, except in paperbark swamps where open cup nests suffered a higher predation rate than domed nests. The study indicates that generalised nest predation rates for tropical regions, even for small areas (e.g. &lt;17 km radius), might overlook substantial variation between habitats. Such variation confounds purported differences in nest predation rates between tropical and temperate regions.

Predation of artificial ground nests in Australian tropical savannas: inverse edge effects

Depredation of artificial ground nests was examined in tropical savanna in northern Australia to assess potential predation pressures on nests of the partridge pigeon (Geophaps smithii), a declining tropical granivore. Predation rates were examined at two sites, Kakadu National Park (which supported a relatively high density of partridge pigeons) and Berry Springs (which had greater habitat fragmentation and comparatively low partridge pigeon density). The effects of distance from road, understorey structure, topography and nest-microsite concealment on nest predation rates were examined. Artificial-nest predation rates were greater at 150 m from roads than &lt;1 m from the roadside. Predation rates did not vary with understorey structure, topography, or level of nest concealment. There was marked variation between sites, with predation levels at Kakadu more than double those recorded for Berry Springs. Discerning predator identity, or even the size of a predator, from marks left in clay eggs proved difficult and was possible for ~35% of predation events. Of these, 42% of predation events involved predators of a size we considered too small to take a natural partridge pigeon nest. We suggest that extrapolation from artificial to natural ground-nest predation rates be undertaken with caution for landscapes such as Australia’s tropical savanna, which supports a high diversity and abundance of small potential predators of artificial nests. There was no evidence of predation by birds, and the methodology proved inadequate for identifying predation by feral cats (Felis catus).

ARE RESULTS OF ARTIFICIAL NEST EXPERIMENTS A VALID INDICATOR OF SUCCESS OF NATURAL NESTS?

Studies using artificial nests to assess rates or patterns of nest predation have increased during recent decades. However, the critical assumption that temporal or spatial patterns of relative predation rates of artificial nests parallel those of natural nests has begun to be questioned. We compared the daily survival rate for 365 artificial nests with that estimated for 295 open nests of passerines, and analyzed the trends in survival rates for both nest types among three breeding seasons and three species of nest plants in the central Monte Desert, Argentina. Daily survival rate for artificial nests (0.737) was significantly lower than that for natural nests (0.925). Trends in survival rates of artificial nests over years and among species of nest plants only partially reflected those of natural nests. Our results support the well established finding that artificial nests may not accurately estimate actual rates of nest predation. Artificial nests may provide an additional source of data to natural nests when testing ecological hypotheses, but artificial nest experiments should be carefully designed (i.e., realistic) and should attempt to identify predators of artificial and natural nests to validate the experimental results.

Effect of egg type on the estimation of nest predation in passerines

We compared predation rates of artificial nests baited with different egg types with the predation rates on nests of the Brown-and-yellow Marshbird (Pseudoleistes virescens), a Neotropical passerine common in the same area, in Argentina. We used deserted natural nests as experimental nests, baited with either Japanese Quail (Coturnix coturnix) or Shiny Cowbird (Molothrus bonariensis) eggs. Each experimental nest was baited with one natural and one paraffin-filled egg. Experimental nests baited with quail eggs suffered lower predation and egg losses than those baited with cowbird eggs. The main cause of egg loss and nest mortality in “cowbird nests” was pecking behavior of cowbirds. However, when we removed the effect of cowbirds, differences still held. In this area, the Shiny Cowbird is common and is the main cause of reduced breeding success of several host species. “Quail nests” had higher nest and egg survival than active Brown-and-yellow Marshbird nests. In contrast, “cowbird nests” and active Brown-and-yellow Marshbird nests had similar nest and egg survival. Experimental nests baited with natural passerine eggs such as those of Shiny Cowbirds seem to approximate the natural nest and egg predation risk for passerines in our study area.

Predation rates of artificial nests in the edge and interior of a southern Victorian forest

Predation rates of nests at human-induced habitat edges may be greater than in forest interior due to differences in predator assemblages and predator activity. I compared the predation rates on 192 artificial nests containing plasticine eggs placed in forest edge and interior sites at Bunyip State Park, Victoria. The nest-predation rates at the forest edge sites were significantly greater (mean = 52–58%) than that at the forest interior sites (mean = 30–39%). The relative rates of predation by birds compared with mammals were significantly greater at forest edge sites (mean = 78–94%) than at forest interior sites (mean = 36–67%). Higher rates of nest predation at forest edges appeared to be due to greater densities of avian predators such as the grey shrike-thrush (Colluricincla harmonica), and/or lower abundances of small mammals. However, biases towards certain predator types may mask real, or create false, patterns in predation rates of artificial nests. A better understanding of how predators respond to artificial nests compared with natural nests is required. Until then, results of predation studies that use artificial nests should be interpreted with caution.