Nest Failure Research Articles

Nest visits and capture events affect breeding success of Yellow-billed and Pacific loons

ABSTRACT Accurate estimates of breeding success are essential for understanding population dynamics and for managing populations. Unfortunately, research activities to collect these data can negatively impact the breeding success of the study species and bias estimates of breeding success. Despite the potential for negative impacts, few studies have documented the effect of capturing incubating adults on nest survival or compared nest survival following different capture methods. In this study we evaluate the impacts of investigator disturbance associated with captures and nest visits on nest survival of Yellow-billed Loons (Gavia adamsii) and Pacific Loons (Gavia pacifica) in the National Petroleum Reserve-Alaska (NPR-A), an area of conservation concern, in 2011–2013. In an effort to reduce capture-related nest failures, we developed a new suspended dive net technique to catch territorial aquatic birds while off their nests. We then compared nest survival following suspended dive net captures to bow-net ...

Tropical montane birds have increased nesting success on small river islands

ABSTRACT Predation is the most important cause of nest failure in birds, and variation in predation risk has been associated with changes in nesting behaviors such as nest-site selection. Some birds choose favorable breeding sites on oceanic or large lake islands to increase their nesting success, but we do not know whether river islands with smaller water barriers provide similar “safe” conditions that decrease predation risk. We tested this in tropical birds by comparing daily survival rates (DSR; i.e. the probability that a nest will survive a single day) and predators identified at nests among bird species that nest on river edges and islands in the Andes. We monitored natural nests of 9 species and placed 70 artificial nests of different shapes (dome, cup, and ground nests) on islands and along river edges. We found that nest survival rates were greater on islands than on river edges for both natural nests (0.989 ± 0.004 vs. 0.0975 ± 0.004) and artificial nests (0.977 ± 0.007 vs. 0.944 ± 0.012). Isol...

Wild Turkey Prenesting-Resource Selection in a Landscape Managed with Frequent Prescribed Fire

Abstract Forage and nesting cover available to female Meleagris gallopavo (Wild Turkey) prior to nesting can influence nest success. Prescribed burns commonly are conducted during the dormant season in southern Pinus (pine) forests in part to improve vegetation conditions for prenesting Wild Turkeys and reduce risk of fire-related nest failure associated with growing-season burning. However, prescribed burning during the early growing season may provide beneficial food and cover for Wild Turkeys. Therefore, we investigated the influence of fire season and frequency and vegetation characteristics on female Wild Turkey habitat selection during prenesting in a Pinus palustris (Longleaf Pine) community managed with frequent growing-season prescribed fire in North Carolina. Growing-season fire history was not predictive of prenesting habitat selection. Females selected forest stands burned during the preceding dormant season, edges of non-forested cover, and creek drainages. On our study area, ericaceous shrub...

Factors Affecting Nest Success of the Oriental Skylark on the Tibetan Plateau

Abstract The Oriental Skylark Alauda gulgula is a widespread species, but its natural history is poorly understood, especially at high altitudes. In this study, we collected breeding information on Oriental Skylarks at an altitude of 3,400 m on the northeastern part of the Tibetan Plateau and examined the effects of nest-site characteristics on nest success. The birds arrived in the study area in April, built nests in tufts of tall grass on the ground and laid their eggs (gray with brown speckles) between May and July. Clutch size averaged 3.3 eggs. Incubation was mainly by the female and lasted 12.4 days. The young left the nest when 9.7 days old. During the breeding season, individual skylarks made 2–3 breeding attempts. Nesting success, as measured by the proportion of nests from which at least one young fledged, was 41.3%. Predation accounted for the majority of failed nests. Some predators (e.g. carnivores) took both skylarks and Mountain Pikas Ochotona curzoniae, although the pikas, as the dominant ...

Evaluating the ecological and behavioural factors influencing Snowy PloverCharadrius nivosusegg hatching and the potential benefits of predator exclosures

SummaryAn understanding of the ecological factors influencing nest success and the effectiveness of management activities focused on improving nest success can be critical to successful conservation strategies for rare or declining species. Over seven breeding seasons (2006–2012) we examined the influence of nest spacing and habitat characteristics on hatching success for the nationally threatened Pacific coast population of the Snowy PloverCharadrius nivosusin coastal Washington, USA in two study areas. Specifically, we assessed the influence of clutch age, nesting season date, distance to conspecific nests, perpendicular distance to the high-tide (wrack) line, vegetation cover and other habitat characteristics at three spatial scales (1m2, 5m2, and 25 m2) centred on the nest. We also assessed the effectiveness of wire mesh cages placed around nests to exclude mammalian and avian nest-predators. We discovered and monitored 307 nests, placed predator exclosures around 142 of these nests and measured habitat variables at 251. Our selected base model included site and quadratic function of season-date. For the analysis examining habitat effects on nest success, only models with distance to nearest active nest ranked higher than the baseline model even when removing the nests that were very distant from conspecific nests (outliers). For these unexclosed nests, predation was the primary source of nest failure and crows and ravens were apparently the primary nest predators. Predator exclosures had a clear positive influence on nest survival. Even though we observed a positive exclosure effect, we recommend that they be used cautiously because we and others have observed adult mortality associated with exclosures. Regardless of the spatial scale, Snowy Plovers are primarily using nest sites with little vegetation, shell or woody material cover suggesting the need for large expanses of very sparsely or unvegetated habitats that allow birds to nest semi-colonially (with near neighbours).

Evidence for an Edge Effect on Avian Nest Predation in Fragmented Afromontane Forests in the Bamenda-Banso Highlands, NW Cameroon

Habitat loss and fragmentation in tropical areas have long been presumed to reduce avian nesting success due to increased predation rates. Nevertheless, this prediction remains largely untested in tropical areas, because empirical data on the impacts of forest fragmentation on nest predation at both the landscape and patch scales in the tropics are still scarce, especially in West Africa. In this study, we examined the edge effects on nest predation rates in a large montane forest block and small forest fragments. Artificial nests used for our experiments mimicked the real nests of passerines confined to montane forest undergrowth in the Bamenda-Banso Highlands, the Northwest region of Cameroon, an endemic bird area of high conservation priority. We found equal overall predation rates in the landscape dominated by the large forest block as well as in the landscape consisting of small forest fragments, implying that the probability of nest failure was not significantly affected by habitat fragmentation on a landscape scale. However, predation rates were higher close to forest edges in the small forest remnants. Since such remnants represent the majority of local montane forests, this result suggests that the edge effect on bird nest predation may reduce nest survival and the population viability of many range-restricted bird species confined to the remaining natural habitats of the Bamenda-Banso Highlands.

Survival of Red-headed Woodpeckers' (Melanerpes erythrocephalus) nests in northern New York

Populations of Red-headed Woodpeckers (Melanerpes erythrocephalus) have declined throughout much of their range. Conservation management to arrest declines or increase populations is difficult, because many aspects of the species' demography remain poorly understood. To address this knowledge gap, we monitored Red-headed Woodpeckers' nests on Fort Drum Military Installation, in northern New York and modeled daily nest survival rate as a function of temporal and habitat-specific covariates. Red-headed Woodpeckers had low overall nest survival rates (nest survival = 32%), and predation was the leading cause (82%) of nest failure. Cavity concealment had the greatest influence on daily nest survival rate, whereby nests with greater vegetative structure surrounding (within 1 m2 of) the nest cavity had higher survival rates, likely because of reduced nest predation. Our estimates of Red-headed Woodpeckers' nest survival were lower relative to other portions of their range and suggest that, at local scales, low reproductive rates near the periphery of the species' distribution may limit population growth.

Nesting ecology of grassland songbirds: effects of predation, parasitism, and weather

Understanding the breeding ecology of grassland birds is vital for understanding the mechanisms underlying their widespread population declines. We describe the breeding biology of Sprague's Pipit (Anthus spragueii), Vesper Sparrow (Pooecetes gramineus), Savannah Sparrow (Passerculus sandwichensis), Baird's Sparrow (Ammodramus bairdii), and Western Meadowlark (Sturnella neglecta) and quantify the effects of nest predation, brood parasitism, and weather on the nest survival of these species in southeastern Alberta. Nest predation was the primary cause of nest failure, accounting for 75% of all nest losses. Daily survival rates were higher during incubation than the nestling stage for the three sparrow species, and nest survival of Baird's Sparrows was highest at intermediate temperatures. For all five species, clutch size, hatching success, and fledging success were within the range of values previously reported for these species in other parts of their range. Brown-headed Cowbirds parasitized nests of all species except Sprague's Pipit, with 4–11% of nests containing cowbird eggs. Savannah Sparrow experienced the highest frequency of brood parasitism and was the only species to successfully fledge cowbird young. Parasitized nests of Savannah Sparrows had reduced clutch size and hatching success, and fledged fewer young compared to non-parasitized nests. The overall cost of parasitism to Savannah Sparrows was at least 1.7 young per successful nest.

Morphological and behavioral evidence of Batesian mimicry in nestlings of a lowland Amazonian bird.

Because predation is the main cause of avian nest failure, selection should favor strategies that reduce the probability of nest predation. We describe apparent Batesian mimicry in the morphology and behavior of a Laniocera hypopyrra nestling. On hatching, the nestling had a distinctive bright orange color and modified feathers all over its body, and 6 days after hatching, it started to move its head very slowly from side to side (in a "caterpillar" movement) when disturbed. These traits gave it a resemblance to a hairy, aposematic caterpillar. This species has a long nestling period for its size (20 days), perhaps due to slow provisioning rates (about one feeding per hour). We argue that the slow growth rate, combined with high nest predation, favors the evolution of antipredation mechanisms such as the unique morphological and behavioral characteristics of L. hypopyrra nestlings.

Breeding ecology and predictors of nest success in the Critically Endangered Ridgway’s HawkButeo ridgwayi

SummaryRidgway’s HawkButeo ridgwayiis a Critically Endangered forest raptor endemic to the island of Hispaniola in the Caribbean. The species is currently limited to a small area on the north-east coast of the island, with fewer than 110 pairs remaining. From 2005 to 2009 we studied its breeding ecology, finding that Ridgway’s Hawks have a clutch size (2.0 ± 0.4 eggs) similar to other tropical raptors and islandButeospecies. Fledging rate of 0.64 fledglings per active nest (fledgling nest-1) with pairs raising a single brood per year was also similar to that of other tropicalButeospecies. Nest success was 40% (n= 151), with the majority of nest failures caused by human disturbance. The two significant predictors of nest success and fledging rate were related to human persecution: nest height and territory disturbance index. Pairs were able to tolerate human activity in their territory if there was no direct disturbance to the immediate nest area. Conservation planning for Ridgway’s Hawk must focus on community awareness programmes targeting local user groups within Los Haitises National Park regarding the uniqueness and endangered status of the hawk, and effective protection of the remaining karst forest in Los Haitises.

Population status and nest success of the Critically Endangered Mariana CrowCorvus kubaryion Rota, Northern Mariana Islands

SummaryThe Mariana CrowCorvus kubaryiis a Critically Endangered species found only on the island of Rota, Northern Mariana Islands. It was extirpated from the neighbouring island of Guam by the introduced brown tree snakeBoiga irregularisand the Rota population has been in decline since at least 1995. We identified only 60 pairs present on Rota in 2007 compared with an estimated 117 pairs in 1998, a decline of nearly 50% in nine years. The decline may be linked to proximity to human activities, though more data are needed. We monitored 204 crow nests between the 1996 and 2009 breeding seasons. Crows initiate clutches between August and April. The overall estimate of nest success was 25.7% (n= 204). On average 49% of pairs produced at least one fledgling per season. The mean number of fledglings per pair per year is 0.66. Mean clutch size was 2.6 (n= 82), mean number of nestlings was 1.4 (n= 106), and mean number of fledglings per nest was 1.3 (n= 68). Daily survival rates declined in later years, and increased during the nest cycle. The number of pairs with successful nests did not change during the study period, nor did the number of fledglings per pair. Predation appeared to be the primary cause of nest failure. The breeding season lasted around nine months and pairs re-nested after failure. Predation of adults and juveniles by cats, combined with possible inbreeding depression, habitat disturbance and human persecution appear to be the cause of decline of the Mariana Crow. We strongly recommend a programme of invasive predator control, habitat maintenance, and captive rearing to ensure the species’ survival.

Effect of Wind Turbine Proximity on Nesting Success in Shrub-nesting Birds

Wind energy development is rapidly expanding globally, as are concerns about the potential threats wind facilities pose to bird and bat populations. To date, many studies have explored the direct impacts of wind turbines on wildlife, such as wildlife-turbine collisions, but few have addressed indirect impacts, such as habitat degradation. These potentially subtle impacts can have far reaching effects on the abundance, distribution, survival, and breeding success of wildlife. We conducted a study to assess whether proximity of wind turbines to shrub-nesting birds influenced rates of nest failure associated mainly with depredation and brood parasitism by Brown-headed Cowbirds (Molothrus ater). During the primary nesting period of five passerine species, we monitored 253 active nests. We used a logistic-exposure method to model nest fate as a function of the important variables identified (including distance from turbine and brood parasitism). Our results indicate little relation between nest success and distance to turbine, with one exception, the Blue-gray Gnatcatcher (Polioptila caerule). For this passerine, we found nests closer to wind turbines had a lower probability of being brood parasitized and subsequently had higher nest success rates. We recommend future studies explore the potential implications of wind energy development on brood parasites, such as the Brown-headed Cowbird. As there is regulatory and social pressure to devise management strategies that reduce the impact of brood parasites on species of concern, any opportunities to decrease the risk of brood parasitism could be of benefit.

Impact of Shiny Cowbird and botfly parasitism on the reproductive success of the globally endangered Yellow CardinalGubernatrix cristata

SummaryThe Yellow CardinalGubernatrix cristatais a globally endangered passerine endemic to southern South America. Although the conservation status of this species is alarming, there is no information about factors that affect its reproductive success. We studied the breeding biology of a Yellow Cardinal population in Corrientes province in north-east Argentina and report reproductive parameters, such as timing of breeding, clutch size, hatching success and chick survival and analyse factors influencing nest survival. The breeding season lasted from October to December with most nesting attempts occurring during the second half of November. Re-nesting after nest failure occurred in approximately 35% of pairs but we did not observe re-nesting after successful attempts. Modal clutch size was three eggs and successful nests fledged on average 1.6 chicks. We observed brood parasitism by Shiny CowbirdsMolothrus bonariensisin 33% of the nests. The main cost of brood parasitism was the puncture of cardinal eggs by cowbird females, which very often resulted in nest abandonment. Another factor reducing reproductive success was parasitism by botfliesPhilornissp., which occurred in 22% of the nests and reduced chick survival. We determined daily nest survival rate with MARK software and found that during the egg stage, it decreased with time of breeding and brood parasitism by Shiny Cowbirds. Our results indicate that Shiny Cowbird and botfly parasitism represent a threat for Yellow Cardinals. Conservation actions to protect the remaining populations of Yellow Cardinals should consider the impact of Shiny Cowbird parasitism.

Comparison of Burning and Weed Barriers for Restoring Common Tern (Sterna hirundo) Nesting Habitat in the Gulf of Maine

Abstract. As seabird nesting colonies have become concentrated on fewer managed islands, available nesting habitat for open-ground nesters such as Common Terns (Sterna hirundo) has rapidly become overgrown by guanofertilized vegetation, leading managers to try various methods of vegetation control to open usable nesting habitat. Two of these methods, burning and synthetic weed barrier treatments, were tested in the summers of 2009 and 2010 to assess their ability to open and maintain Common Tern nesting habitat on two nearshore seabird nesting islands in Maine. Treatments were applied to overgrown habitat pre-nesting, and vegetation regrowth and Common Tern nest and fledging success were monitored in treated plots, untreated vegetation plots and occupied Common Tern nesting habitat. Burned areas did not remain open for the full nesting season, but regrew shortly after egg-laying, creating unsuitable vegetation structure and leading to near-complete nest failure in these plots. However, vegetation characte...

Southern giant Petrel Macronectes giganteus nest attendance patterns under extreme weather conditions.

Differences in nest attendance between genders in seabirds may be related to morphological differences. Southern giant petrel is a dimorphic species with gender-specific foraging behavior. The objective of this study was to investigate sex-related differences in nest attendance during the breeding period of southern giant petrels by presence/absence patterns of both sexes during incubation and compare use of the colony after nest failure. Fourteen birds were tagged with digitally coded radio-transmitters in a colony at Elephant Island, Antarctica, in the beginning of 2009/2010 breeding season. Females were present during 18 periods (min. 3 days, max. 9 days) and males only in five periods (min. 2 days, max. 13 days). The difference in mean number of radio signals per day between females (4330; s.e. 313.5) and males (2691; s.e. 248.6) was highly significant (t = 4.3; d.f. = 199; P < 0.001; Fig. 4 ). As consequence of the severe weather conditions that year, all tagged birds failed to reproduce. After abandonment of the nests, the presence of both genders decreased drastically, although the tagged individuals stayed in the area. Under severe weather conditions female Southern Giant Petrels continue breeding while males abandon the nest earlier.

Factors influencing nest survival and renesting by Piping Plovers in the Great Lakes region

ABSTRACT Renesting is an important breeding strategy used by birds to compensate for nest failure. If birds renest, clutch removal for captive rearing can be used to augment endangered populations; however, not all individuals renest following nest loss, and later nesting attempts may have lower survival rates and clutch sizes. We investigated variation in nest initiation date, clutch size, daily nest survival, renesting propensity, and renesting intervals of federally endangered Great Lakes Piping Plovers (Charadrius melodus) from 1993 to 2010. We also compared productivity under hypothetical clutch removal for captive rearing vs. non-removal scenarios. Nest initiation date was earlier for older adults and was more strongly affected by female than male age. Clutch size and nest survival decreased with later nest initiation, and nest survival increased with male age and nest age until close to hatching. Overall, Piping Plovers replaced 49% of failed nests. Renesting propensity decreased with later date, i...

Immune-related effects from predation risk in Neotropical blue-black grassquits (Volatinia jacarina)

Predation is a major force shaping natural history traits of birds because of their vulnerability during nesting and higher visibility during diurnal activities. For most birds in the Neotropics, predation is the major cause of nest failure due to the region's high diversity and abundance of predators. The blue-black grassquit (Volatinia jacarina), similarly to other small passerines in the savanna region of central Brazil, suffers extremely high rates of nest predation. Additionally, males may be particularly vulnerable to predators since they are very conspicuous when executing courtship displays. We assessed some of the non-lethal costs of predation risk on this species by comparing physiological and morphological parameters of birds exposed to predator vocalizations with that of control subjects exposed to non-predator vocalizations. Birds exposed to the predator vocalizations exhibited an immune-related reaction (changes in their H/L ratio), but no changes were observed in other biological parameters measured.This article is part of a Special Issue entitled: Neotropical Behaviour.

Preferred nest site characteristics reduce predator-specific predation risk in a canopy-nesting raptor

Habitat features influence nest survival and, as a result, identifying relationships between habitat characteristics and nest survival remains a central focus among studies of avian reproduction. In cases where nest predation is the main cause of failure, knowing how the habitat affects predation risk may provide managers with a tangible means by which to improve reproductive success. The Mississippi kite (Ictinia mississippiensis) is a species of regional conservation concern due to small population sizes and high rates of nest failure. We monitored Mississippi kite nests, documented causes of nest failure, and examined relationships between habitat features and predator-specific patterns in nest predation in a floodplain forest in east-central Arkansas. We identified Texas ratsnakes (Pantherophis obsoletus) and owls (Strigidae) as the dominant nest predators and predation by each was influenced by different habitat features. Ratsnake predation was greater in areas with fewer overstory trees and when kite nests were positioned farther above the tree canopy. Owls were more likely to depredate nests farther from the forest edge and nests that had less canopy coverage around them. Our results illustrate that the nest site characteristics preferred by kites reduce nest predation risk, indicating most of the management actions proposed to promote kite nesting are likely to create or maintain quality habitat for this species in the Mississippi Alluvial Valley. Beyond knowing the main causes of nest failure in kites, our results may also provide a glimpse into threats faced by mid-story and other canopy-nesting birds, a guild for which very little information exists regarding causes of nesting failure. © 2014 The Wildlife Society.

Breeding biology of the European GreenfinchChloris chlorisin the loquat orchards of Algeria (North Africa)

Few data are available on passerines’ breeding in farmlands in Algeria. The breeding biology of the Greenfinch was studied in the loquat orchards to describe the timing of breeding, clutch size, number of nestlings hatched and fledged, assess nesting success and the main causes of nesting attempt failure, and investigate nest placement in the loquat trees. Nests were monitored intensively to quantify the number of nesting attempts and territory densities. The breeding season extended from mid-March to late May. Mean clutch size was 4.37 ± 0.04, number of hatchlings was 2.62 ± 0.15, and number of fledglings per successful nest was 3.44 ± 0.16. Clutch size differed significantly across the breeding season. The density of breeding pairs was 12.83 ± 0.83 p/ha, and breeding success was lower than that reported in other studies of finches and passerine birds. Predation was the cause of most nest failures. Loquat orchards seem to be the main suitable breeding habitat for the Greenfinch, and differences in some b...

Integrating demographic data: towards a framework for monitoring wildlife populations at large spatial scales

SummaryLandscapes are becoming increasingly intensively managed resulting in greater anthropogenic disturbance of ecosystems. Effective policies for conservation and management of wildlife populations will require a mechanistic understanding of the processes underlying the population responses to these changes. Detailed demographic studies are often of individual populations in relatively stable habitats, whereas there is a need to characterize demographic variation at larger scales in wider landscapes that are subject to environmental change.We use long‐term (18–46 years) data sets, gathered by volunteers acrossBritain, to parameterizeBayesian state‐space demographic population models for 17 widely occurring bird species. As some demographic processes were not quantified directly, we introduce a scaling parameter (ρ) to account for this unmeasured variation, and assess the extent to which this influences our ability to understand the processes driving population change.The population models provided a good fit to the population trajectory in all but one species (the nocturnal tawny owlStrix aluco). The scaling parameter generally showed little annual variation and did not make a major contribution (&lt;12%) to population change among passerine species. For five non‐passerine species, the contribution was still not large (11–21%), but did indicate the importance of unmeasured demographic variables in these species.We were able to retrieve known demographic signals both within and across species. The importance of the nest failure rates was greater for species that construct nests in open rather than cavity situations. We also confirmed the demographic causes of population decline in two species of conservation concern, song thrush and lapwing, as changes in juvenile survival and reproductive success respectively. Furthermore, we show that population dynamics of declining species are generally driven more by recruitment than increasing species (for which variation in adult survival is more important).These analyses demonstrate that volunteer‐based monitoring programmes can provide insight into population changes at large spatial scales across a range of species. By facilitating the combination of data sets on different demographic parameters, the integrated approach adopted here allows important demographic parameters to be identified, even if they are not measured directly.