An inexpensive method for identifying predators of passerine nests using tethered artificial eggs

We identified nest predators of two European thrush and three European finch species in the central North Island, New Zealand, using artificial clay eggs in active natural nests. The acceptance of the artificial egg by females was 75%, with low rates of female egg ejection (7%) or desertion (7%). Due to high predation rates we could not confirm the acceptance of six (11%) artificial eggs before predation occurred. Of the 57 nests that received an artificial egg 30 were preyed upon. We were able to successfully identify predators from 18 (60%) nests by imprints left in the artificial eggs, with rats (Rattus sp.), Australasian Harriers (Circus approximans) and Australian magpie (Gymnorhina tibicen) accounting for nine, eight and one of the predatory events respectively. In the remaining twelve predatory events imprints were too faint or no marks were left on the clay egg for identification. This study successfully demonstrates the use of an inexpensive, seldom-used method for quantifying and identifying nest predators, with low rates of nest abandonment and high rates of predator identification. We believe this method could add valuable information for future studies of nest predation in New Zealand.     

Using artificial nests to predict nest survival at reintroduction sites

Artificial nests are frequently used to assess factors affecting survival of natural bird nests. We tested the potential for artificial nests to be used in a novel application, the prediction of nest predation rates at potential reintroduction sites where exotic predators are being controlled. We collected artificial nest data from nine sites with different predator control regimes around the North Island of New Zealand, and compared the nest survival rates with those of North Island robin (Petroica longipes) nests at the same sites. Most of the robin populations had been reintroduced in the last 10 years, and were known to vary in nest survival and status (increasing/stable or declining). We derived estimates of robin nest survival for each site based on Stanley estimates of daily survival probabilities and the known incubation and brooding periods of robins. Estimates of artificial nest survival for each site were derived using the known fate model in MARK. We identified the imprints on the clay eggs in the artificial nests, and obtained different estimates of artificial nest survival based on imprints made by different potential predators. We then compared the value of these estimates for predicting natural nest survival, assuming a relationship of the form s = αpβ, where s is natural nest survival and p is artificial nest survival. Artificial nest survival estimates based on imprints made by rats (Rattus spp.) and brushtail possums (Trichosurus vulpecula) were clearly the best predictors (based on AICc), and explained 64% of the variation in robin nest survival among sites. Inclusion of bird imprints in the artificial nest survival estimates substantially reduced their predictive value. We suggest that artificial nests may provide a useful tool for predicting the suitability of potential reintroduction sites for New Zealand forest birds as long as imprints on clay eggs are correctly identified.     

Sign left by brushtail possums after feeding on bird eggs and chicks

Brushtail possums (Trichosurus vulpecula) were offered Japanese quail (Coturnix japonica) eggs and day-old domestic chickens (Gallus gallus) during a captive feeding trial. Differences in feeding sign left by possums of differing sex, age class, and hunger were slight or absent. Possum feeding trial remains were also compared with remains of North Island robin (Petroica australis longipes) and North Island tomtit (Petroica macrocephala toitoi) eggs and chicks preyed on by ship rats (Rattus rattus) at videoed nests. Eggs fed on by possums were frequently crushed or had crushed shell margins whereas eggs preyed on by ship rats often had jagged shell margins and separate small shell fragments. Possums that ate chickens mostly left partially eaten carcasses with torn flesh, of which 50% were at least partially skinned. Ship rats left partially eaten birds with chewed flesh and bones but did not skin carcases. Possums rarely spat out shell pellets but produced feather pellets on eight of 13 occasions. Egg shell remains left by possums were indistinguishable from those left by ship rats for 11% of 72 shell remains examined from the feeding trial. Characteristic sign should enable possums and ship rats to be differentiated as predators after most but not all predations.     

Nest predators of Lance-tailed Manakins on Isla Boca Brava, Panamá

ABSTRACT.   Nest predation is often the primary cause of nest failure for passerines. Despite this, little is known about predation rates and the nest predators of birds in the tropics. I used video cameras to monitor seven Lance-tailed Manakin ( Chiroxiphia lanceolata ) nests on Isla Boca Brava, Panamá. One nest fledged young and six nests failed due to predation. I recorded five predation events involving four avian predators and one mammalian predator. Crested Oropendolas ( Psarocolius decumanus ) predated two nests and a Roadside Hawk ( Buteo magnirostris ) and a Black-chested Jay ( Cyanocorax affinis ) each predated one. The mammalian predator was a common opossum ( Didelphis marsupialis ). All avian predation was diurnal; the mammalian predation was nocturnal. My results suggest that tropical birds are subject to a diverse suite of nest predators, and that avian predators may be an important cause of nest failure at my study site.     

Predation by mustelids and rodents on the eggs and chicks of native and introduced birds in Kowhai Bush, New Zealand

Prior to human settlement the endemic New Zealand avifauna evolved in the absence of mammalian predators. Subsequently mustelids, rodents and feral cats have become established and frequently prey on birds and nests. It has been suggested that, because of their evolutionary history, the endemic birds are especially susceptible to such predators. In this paper predation by mustelids and rodents on the eggs and nestlings of eight species of native bird is compared with that on five species of introduced European passerine inhabiting the same lowland forest.
Final outcomes were known for 101 nests of native birds and 48 nests of introduced birds found during three breeding seasons. There was no significant difference between the two groups in frequency of predation. Native birds lost 70-1% of their nests to predators and introduced birds 64-6%. Most predations occurred during the egg stage. Clutch size did not influence frequency of predation, but brood size did for Fantails and introduced birds. Stoats and weasels were responsible for 77-9% of predations on native birds and 77-4% on introduced birds; corresponding percentages for rodents (principally ship rats) were 14-7% and 19-4%. Mustelids destroyed proportionately more nests with chicks than with eggs, whereas rodents did the reverse. Predation on both groups of birds was not influenced by their nesting habitat, the species of tree used for nesting, or the height and position of the nest. The vulnerability to introduced predators of native New Zealand birds is discussed in relation to the historical declines of many species, and also their life-history patterns.     

Understanding avian nest predation: why ornithologists should study snakes

Despite the overriding importance of nest predation for most birds, our understanding of the relationship between birds and their nest predators has been developed largely without reliable information on the identity of the predators. Miniature video cameras placed at nests are changing that situation and in six of eight recent studies of New World passerine birds, snakes were the most important nest predators. Several areas of research stand to gain important insights from understanding more about the snakes that prey on birds' nests. Birds nesting in fragmented habitats often experience increased nest predation. Snakes could be attracted to habitat edges because they are thermally superior habitats, coincidentally increasing predation, or snakes could be attracted directly by greater prey abundance in edges. Birds might reduce predation risk from snakes by nesting in locations inaccessible to snakes or in locations that are thermally inhospitable to snakes, although potentially at some cost to themselves or their young. Nesting birds should also modify their behavior to reduce exposure to visually orienting snakes. Ornithologists incorporating snakes into their ecological or conservation research need to be aware of practical considerations, including sampling difficulties and logistical challenges associated with quantifying snake habitat use.     

Predators at bird nests in a northern hardwood forest in New Hampshire

ABSTRACT.   Nest predation is the primary cause of nest failure in most passerine birds, and increases in nest predation associated with anthropogenic habitat disturbance are invoked as explanations for population declines of some bird species. In most cases, however, the identity of the nest predators is not known with certainty. We monitored active bird nests with infrared time-lapse video cameras to determine which nest predators were responsible for depredating bird nests in northern New Hampshire. We monitored 64 nests of 11 bird species during three breeding seasons, and identified seven species of predators during 14 predation events. In addition, we recorded two instances of birds defending nests from predators and, in both cases, these nests were ultimately lost to predation. These results contrast with other studies in terms of the relatively high proportion of nests depredated by raptors and mice, as well as the absence of any predation by snakes. The diverse suite of predators in this and other studies is likely to confound our understanding of patterns of nest predation relative to fragmentation and habitat structure.     

Experimental evidence for edge-related predation in a fragmented agricultural landscape

Abstract This study tested the hypothesis that increased predation of experimental nests occurs close to a forest edge in a fragmented agricultural landscape. Artificial nests and eggs of willie wagtails Rhipidura leucophrys and superb fairy-wrens Malurus cyaneus were used in experiments to assess the extent and nature of predation occurring throughout the known breeding seasons of these species. Predators were identified by the imprints they left in plasticine eggs, and by remote photography. Surveys of avian predators were undertaken to investigate the relationship between predation intensity and predator distribution and abundance. Avian predators accounted for almost all predation for which a predator could be identified (96%). Five of seven predator species photographed attacking wagtail nests were corvids or artamids. Fairy-wren nests suffered relatively low rates of predation (29%) compared to wagtail nests (87%). Increased predation at the habitat edge was recorded for wagtail nests only; predation was correlated with the distribution and abundance of predatory avian species. The different extent and pattern of predation on fairy-wren nests could be explained by problems in detecting predation by mammals, and by possible failure of avian predators to locate the cryptic nests.     

Factors affecting piping plover hatching success on Long Island,New York

Low hatching success may limit progress towards reaching productivity goals for Atlantic Coast piping plover (Charadrius melodus) recovery, despite management strategies to protect eggs from predators and decrease human disturbance of birds on nests. We measured piping plover hatching success on Eastern Long Island beaches and identified the major causes of egg failure to better understand why eggs that were otherwise intact (not depredated or destroyed by tidal flooding) failed to hatch. We documented egg and nest fates, dissected contents of unhatched eggs to determine viability, and recorded human and predator activity near a subset of plover nests on Suffolk County Parks properties. The low hatching success we recorded (0.60) in 2006 and 2007 would require higher chick survival rates than are typically observed for piping plovers to meet recovery targets for productivity. Few eggs showed signs of poor viability and overall egg hatchability was comparable to other ground nesting birds. Most egg failure was due to either depredation at unexclosed nests or nest abandonment by adults. The best predictor of nest abandonment was the maximum number of red fox tracks (Vulpes vulpes) counted on nearby transects (β = −1.16, 95% CI: −2.0 to −0.3) and we found evidence that plovers abandoned eggs in response to predation risk (e.g., a fox circling a nest exclosure). Adults from abandoned nests may have deserted eggs or been depredated. In either case, intact and viable eggs were abandoned. Nest abandonment was not related to human activity near nests, which were buffered from human disturbance by symbolic string fencing. Our results suggest that depredation and nest abandonment (e.g., desertion or death of adults) due to predator disturbance, not human disturbance or poor egg viability, contributed to the low hatching success we recorded. Active predator removal in addition to modification of predator exclosure use and design may be necessary to prevent direct (egg depredation) and indirect (nest abandonment) negative effects of predators on hatching success. © 2010 The Wildlife Society.     

Nest height, nest concealment, and predator type predict nest predation in superb fairy-wrens (Malurus?cyaneus)

Three factors and their interaction effects are increasingly recognized as important determinants of nest predation: nest concealment, nest height, and predator type. The risk of nest predation is predicted to vary across these variables because of nest detectability and accessibility. In general, however, few studies examine how these three variables interact in relation to nest predation, focusing instead on either nest concealment or nest height (whereby predator identity is usually not known). In this study, we examine the role of nest concealment and nest height for nest survival using both artificial and natural nests in the superb fairy-wren (Malurus cyaneus). We indirectly identified potential predators through marks left on artificial eggs and footprints left on tracking tunnels. Predation level at artificial nests was lower than at natural nests, and this could be due to a failure of some nest predators to locate cryptic nests in the absence of cues provided by parental activity. Our results supported the prediction that exposed and concealed nests have different levels of nest predation, which can be explained by variation in predator type. Visual predators were only detected at exposed nests, and survival from visual predators was lower for high nests that were also exposed. However, olfactory predators were detected irrespective of nest height or nest concealment. Because rodents use olfaction to locate nests, this could explain the lack of association between nest concealment and predation outcome at low nests. In addition, rodent footmarks near nests were significantly associated with rodent tooth marks on eggs.     

Nest Predation Deviates from Nest Predator Abundance in an Ecologically Trapped Bird

In human-modified environments, ecological traps may result from a preference for low-quality habitat where survival or reproductive success is lower than in high-quality habitat. It has often been shown that low reproductive success for birds in preferred habitat types was due to higher nest predator abundance. However, between-habitat differences in nest predation may only weakly correlate with differences in nest predator abundance. An ecological trap is at work in a farmland bird (Lanius collurio) that recently expanded its breeding habitat into open areas in plantation forests. This passerine bird shows a strong preference for forest habitat, but it has a higher nest success in farmland. We tested whether higher abundance of nest predators in the preferred habitat or, alternatively, a decoupling of nest predator abundance and nest predation explained this observed pattern of maladaptive habitat selection. More than 90% of brood failures were attributed to nest predation. Nest predator abundance was more than 50% higher in farmland, but nest predation was 17% higher in forest. Differences between nest predation on actual shrike nests and on artificial nests suggested that parent shrikes may facilitate nest disclosure for predators in forest more than they do in farmland. The level of caution by parent shrikes when visiting their nest during a simulated nest predator intrusion was the same in the two habitats, but nest concealment was considerably lower in forest, which contributes to explaining the higher nest predation in this habitat. We conclude that a decoupling of nest predator abundance and nest predation may create ecological traps in human-modified environments.     

Nest predation in forest birds: influence of predator type and predator's habitat quality

We used the introduction of a generalist nest predator, the red squirrel Tamiasciurus hudsonicus, and of a large herbivore, the Sitka black-tailed deer Odocoileus hemionus sitkensis, to the islands of Haida Gwaii (Queen Charlotte Islands, British Columbia, Canada) to study how predator assemblage and habitat quality and structure influenced nest predation in forest birds. We compared losses of natural nests to predators on islands with and without squirrels. We selected nine islands with or without squirrel or deer and used 506 artificial nests put on the ground or in shrubs to further analyse variation of nest predation with predator assemblage and habitat quality for the predators. For both natural and artificial nests predation risk was higher in presence of squirrels. But predation risk varied within island categories. In presence of squirrels it was highest in stands with mature conifers where it fluctuated from year to year, in response to fluctuations in squirrel abundance. Vegetation cover around the nest had little effect on nest predation by squirrels. Where squirrels were absent, nest predation concentrated near predictable food sources for corvids, the main native predators, and increased with decreasing vegetation cover, suggesting that removal of the vegetation by deer increased the risk of predation by native avian nest predators that use visual cues. Predation risk in these forests therefore varies in space and time with predator composition and with quality of the habitat from the predators' perspective. This temporal and spatial variation in predation risk should promote trade-offs in the response of birds to nest predation, rather than fine-tuned adaptations to a given predation pattern.     

It’s a dog-eat-croc world: dingo predation on the nests of freshwater crocodiles in tropical Australia

Predation on eggs is an important source of mortality for many long-lived organisms, but causes of egg mortality from specific predators remain poorly known in most cases. Understanding the identity of predators, and the rates and determinants of their effects on a cohort of recruits, can provide a valuable background for attempts to exploit, control or conserve populations. We used remotely triggered cameras to study predation on the nests of freshwater crocodiles (Crocodylus johnstoni) inhabiting Lake Argyle, in tropical Australia. We also supplemented our work on natural crocodile nests with artificial nests. Overall, 80 of 111 natural nests were opened by predators, and predation occurred throughout the study period (7 weeks). Unlike in other parts of the species’ range, most nest-robbers were dingoes (Canis lupus dingo, responsible for 98% of all predator visits in the northern sites, and 54% in the Ord River site), with minimal additional predation by reptiles and birds. Contrary to expectation, rates of nest predation were not influenced by spatial clumping of nests: the probability of predation per nest did not change with total numbers of nests laid in an area, and artificially aggregated versus dispersed nests experienced similar levels of predation. Nest vulnerability was linked to abiotic features including slope of surrounding banks, compactness of nesting substrate, and distance from the nearest forest. Abundant aquatic food resources support a large crocodile population, but a lack of suitable nest-sites forces the crocodiles to concentrate nesting in small areas readily accessible to wide-ranging nest predators. Collectively, our results suggest that distinctive attributes of the lakeside landscape alter predator guilds and fashion unique predator–prey interactions.     

Effects of Mesopredators on Nest Survival of Shrub-Nesting Songbirds

ABSTRACT Although nest predation is often the single largest source of mortality in avian populations, manipulative studies to determine predator impacts on nest survival are rare, particularly studies that examine impacts of mid-size mammalian predators (hereafter, mesopredators) on nest survival of shrub-nesting birds. We quantified nest survival and identified nest predators of shrub-nesting songbirds within 4 large (approx. 40-ha) exclosures and 4 control sites within a longleaf pine (Pinus palustris) ecosystem. During 2003–2006, we located and monitored 535 shrub nests (222 with videography) for 4,804 nest-days to quantify daily nest survival and document predation events. We found no support for a treatment effect, suggesting mesopredators had little impact on daily nest survival (0.9303 in controls and 0.9260 in exclosures) of shrub-nesting songbirds. For the 5 most commonly monitored species, daily nest survival within species was constant. Our analysis suggested that shrub nests were most vulnerable during the nestling stage and presence of cameras on nests increased survival with the increase in survival being more pronounced during the incubation stage. We filmed 107 nest predation events, identifying predators at 88 nests. Of these 88 nests, snakes caused 33%, red imported fire ants (hereafter fire ants, Solenopsis invicta) 28%, raptors 17%, corvids 8%, mesopredators 6%, and small mammals 8% of nest predations. Cause-specific nest predation in controls and exclosures did not differ from expectation, providing evidence that compensatory predation did not occur. Nest predators differed from expectation with regard to nest stage; fire ants and raptors only depredated nests during the nestling stage. Presence of cameras had no effect on nest abandonment. Fire ants were the most prevalent nest predator, and nest predation by fire ants was only observed on nestlings, potentially reducing likelihood of renesting. Magnitude and timing of fire ant predation suggests that fire ants may be the most influential nest predator of shrub-nesting birds within the longleaf pine ecosystem. Our data suggest that controlling mesopredators will have no effect on nest success of shrub-nesting birds within longleaf pine forests.     

Impact of brood parasitism and predation on nest survival of the fan-tailed gerygone in New Caledonia

Predation and brood parasitism are common reasons for nesting failure in passerine species and the additive impact by invasive species is a major conservation concern, particularly on tropical islands. Recognising the relative contribution of the different components of nesting failure rates is important to understand co-evolutionary interactions within brood parasite–host systems. In the remote archipelago of New Caledonia, the fan-tailed gerygone Gerygone flavolateralis is the exclusive host of the brood-parasitic shining bronze-cuckoo Chalcites lucidus. Additionally, invasive rodents also possibly have an impact on breeding success. To estimate the impact of potential nest predators, we 1) video monitored nests to identify predators, 2) estimated the probability of predation based on nest visibility and predator abundance and 3) tested the possibility that the location of experimental nests and lack of odour cues decrease the predation by rodents. In addition, we estimated nest survival rates using data collected in different habitats over the course of eight breeding seasons. Nesting success of fan-tailed gerygones was relatively low and predation was the main cause of nesting failure. We recorded mainly predation by native birds, including the shining bronze-cuckoo, whereas predation by rats was rare. In open habitats predation by cuckoos was much lower than predation by other avian predators. Neither predator activity around nests nor nest visibility influenced the probability of predation. Experimental nests in more accessible locations and containing an odorous bait were more exposed to rodent predation. Apparently, the fan-tailed gerygone has either never been specifically vulnerable to predation by rats or has developed anti-predator adaptations.     

Predation risk effects on fitness related measures in a resident bird

Predation risk is thought to be highly variable in space and time. However, breeding avian predators may create locally fixed and spatially fairly predictable predation risk determined by the distance to their nest. From the prey perspective, this creates predation risk gradients that potentially have an effect on fitness and behavioural decisions of prey. We studied how breeding avian predators affect habitat selection (nest location) and the resulting fitness consequences in a northern population of resident willow tit ( Parus montanus ). Data included 429 willow tit nests over a four year period in a landscape containing a total of 33 avian predator nests. Willow tit nests were located randomly in the landscape and no predator avoidance in habitat selection or emptying of territories in proximity to predators was observed. Nestling size, however, was positively associated with distance from predator nests (n=252). Nestling mass and wing length were about 4.5% smaller close to predator nests compared to nestlings raised far from predator nests. Tarsus length also exhibited a positive relationship with increasing distance from predator nest but this was limited to habitats of young forests and pine bogs or dense mixed forests (4% increase). It is likely that habitat structural complexity influenced the perception of predation risk in different habitats. Our results indicate that willow tits do not provide reliable cues of predator free habitats for settling migrants. Nonetheless, breeding avian predators may create predictable predation risk in the landscape which is an important factor affecting reproductive success and potentially the demography of prey populations.     

Egg concealment is an antipredatory strategy in a cavity‐nesting bird

Birds have developed different behavioural strategies to reduce the risk of predation during the breeding period. Bird species that nest in the open often cover their eggs to decrease the risk of predators detecting the clutches. However, in cavity nesters, the potential functions of egg covering have not been explored despite some bird species that nest in cavities also covering their eggs as open nesters do. We analysed whether egg covering is an antipredatory behaviour in the blue tit (Cyanistes caeruleus). We simulated an increase in the perceived risk of predation at experimental nests by adding predator scent inside the nest boxes during the egg‐laying period, whilst adding lemon essence or water to control nest boxes. Birds exposed to predator chemical cues in the nest of experimental pairs more frequently covered their eggs than birds exposed to an odorous control. These results suggest that egg covering may have evolved as an antipredatory behaviour also in cavity nesters to reduce the risk of egg predation and thus increase reproductive success in birds.     

Different nest predator guild associated with egg size in the Patagonian temperate forest

Capsule: Studies of nest predation using artificial nests need to consider the effect of egg size on the types of predator that are detected.

Aims: To estimate the nest predation rate in the Patagonian temperate forest and evaluate the influence of egg size on predator guild.

Methods: On different plant species, we placed 108 nests each containing eggs of either Atlantic Canary Serinus canaria or Common Quail Coturnix coturnix, and a model clay egg of equal size to the real egg. Nest predators were identified from the marks left on the clay eggs or by videos recorded using camera traps.

Results: 86% of the nests were predated. Birds, mainly Chimango Caracara Milvago chimango, were the main nest predators. A marsupial, the Monito del Monte Dromiciops gliroides, and rodents also contributed to nest predation. Nest predation rates were similar for both egg sizes but the nest predator guild was different. Birds and rodents preyed on both eggs but the Monito del Monte consumed mainly small eggs.

Conclusion: Egg size did not influence the rate of nest predation but, instead, affected the nest predator guild. Consequently, in order to avoid underestimating the impacts of small predators, egg size should be considered in studies of nest predation.     

Meta‐analyses of nest predation in temperate Australian forests and woodlands

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

Landscape features associated to wind farms increase mammalian predator abundance and ground-nest predation

Wind farm implementation is a rapidly growing source of landscape transformation that may alter ecological processes such as predator–prey interactions. We tested the hypothesis that wind farms increase the activity of nest predators and, ultimately, increment ground-nest predation rates. We placed 18 plots in Iberian shrub-steppes (11 at control and seven at wind farm sites), each one comprised nine artificial ground-nests (three quail eggs/nest). Artificial nests were placed during two events: at the beginning (April) and at the end (June) of the breeding season in 2016 (n?=?324 artificial nests). We estimated the relative abundance of avian and large mammalian predators in the surroundings of each plot and recorded nest fate after 12 days exposure. We also measured variables at landscape and microhabitat scale that potentially affect predator abundance and nest predation. Wind farm sites contained higher cover of gravel roads and more large mammalian predators. Moreover, the abundance of large mammalian predators increased with surrounding cover of both trees and gravel-roads. Avian predator abundance and nest predation rates did not differ between control and wind farm sites, though nest predation did increase with the surrounding cover of crops and gravel roads. Lastly, nest predation was higher at the end of the breeding season and decreased with moss and lichen cover. Our results support previous evidence on the increase of mammalian predator abundance as the surface area of gravel-roads increases, pointing towards a potential mechanism for wind farms leading to rise ground-nest predation. Future wind energy projects should minimize the development of gravel-roads for wind turbine access or maintenance.