Nest Success Research Articles

Number of White Stork Ciconia ciconia Nests in Latvia Between 1934 and 2014

Abstract The article summarises the results obtained during the 7th International White Stork Census 2014 in Latvia as well as analyses of changes since 1934. More than 2000 participants were involved in the census. About 14,000 pairs of white storks (WS) were found nesting in Latvia in 2014, i.e. about 52% more than in 1934, and about 25% more than in 1994 and 2004. The breeding density was one of the highest in the breeding area — on average, 21.7 occupied nests/100 km2 territory and 60.8 nests/100 km2 agricultural lands. The proportion of occupied nests in 2014 was 90.1%, and the proportion of successful ones — 95.7%. The average number of raised chicks decreased from 2.7 in occupied nests and 2.8 in successful nests in 1934 to 2.1 and 2.4 in 2014, correspondingly. The main reasons for this decrease were deterioration of feeding conditions (amount and availability of food, as well as the regionally growing use of agricultural chemicals). Since 1934, considerable changes in WS nest location and human aid in their construction have been observed. Eighty years ago, an absolute majority of nests (about 80%) were built with human aid (artificial nest support) on trees; whereas in 2014, only 3.5% such nests were registered. Most nests (64.8%) in 2014 were built on electric poles without artificial support. According to observations after 2014, the growth of the breeding population of WS in Latvia has come to an end, and even a slight regional decrease has been observed. Nevertheless, at present, there are no reasons to consider the local breeding population of the WS as being endangered and vanishing.

A spatially explicit modeling framework to guide management of subsidized avian predator densities

AbstractAnthropogenic resource subsidization across western ecosystems has contributed to widespread increases in generalist avian predators, including common ravens (Corvus corax; hereafter, raven). Ravens are adept nest predators and can negatively impact species of conservation concern. Predation effects from ravens are especially concerning for greater sage‐grouse (Centrocercus urophasianus; hereafter, sage‐grouse), which have experienced prolonged population decline. Our objectives were to quantify spatiotemporal patterns in raven density, evaluate sage‐grouse nest success concurrent with fluctuating raven densities, and demonstrate a spatially explicit decision support tool to guide management applications to appropriate conflict areas. We combined ~28,000 raven point count surveys with data from more than 900 sage‐grouse nests between 2009 and 2019 within the Great Basin, USA. We modeled variation in raven density using a Bayesian hierarchical distance sampling approach with environmental covariates on detection and abundance. Concurrently, we modeled sage‐grouse nest survival using a hierarchical frailty model as a function of raven density and other environmental covariates that influence the risk of nest failure. Raven density commonly exceeded 0.5 ravens km−2and increased at low elevations with more anthropogenic development and/or agriculture. Reduced sage‐grouse nest survival was strongly associated with elevated raven density (e.g., >0.5 ravens km−2) and varied with topographic ruggedness, shrub cover, and burned areas. For conservation application, we developed a spatially explicit planning tool that predicts nest survival under current and reduced raven numbers within the Great Basin to help direct management actions to localized areas where sage‐grouse nests are at highest risk of failure. Our modeling framework can be generalized to multiple species where spatially registered abundance and demographic data are available.

Nest success of ground-nesting ducks in the wetlands of Great Salt Lake, Utah.

The number of ground-nesting ducks in the wetlands of Great Salt Lake, Utah has drastically decreased in the past few decades. A potential cause for this decline is the increase of predator species and their abundances, which has caused most nests to fail from depredation. Ground-nesting ducks may be able to reduce the risk of nest depredation by selecting nest sites where local physical structures or vegetation provides olfactory or visual concealment. To test this, we used logistic exposure models to look at the effect of nest-site characteristics on daily survival rates (DSRs) of nests during 2019, 2020, and 2021 in the wetlands of Great Salt Lake, Utah. We found 825 duck nests including 458 cinnamon teal (Spatula cyanoptera), 166 mallards (Anas platyrhynchos), and 201 gadwalls (Mareca strepera). DSRs were 0.9714 ± 0.0019 in 2019, 0.9282 ± 0.0049 in 2020, and 0.8274 ± 0.0185 in 2021. Survival rates varied among years but not among duck species. Striped skunks (Mephitis mephitis) and raccoons (Procyon lotor) were responsible for 85% of depredated nests. Nests located near other duck nests had higher DSRs than more dispersed nests. Neither visual nor olfactory characteristics correlated with increased DSRs based on AICc analysis. Nests located inside a mixed nesting colony of American avocets (Recurvirostra americana), black-necked stilts (Himantopus mexicanus), and common terns (Sterna hirundo) had higher DSRs than duck nests outside the colony. Increased nesting densities of ducks and other colonial waterbirds had the greatest impact on nesting success. Increased nest density may be encouraged through early spring green-up.

Fusarium solani Species Complex (FSSC) in Nests of Hawksbill Turtles (Eretmochelys imbricata) with High Hatching Success in Melaka, Malaysia

Hatching failure is one of the threats to the declining sea turtle population. Sea turtle egg fusariosis, an emerging fungal disease, has been linked to lower hatching success in sea turtle nests. The disease is associated with the presence of members of the (Fusarium solani species complex (FSSC). Samples of cloacal mucus, nest sand, eggshells, and eggs were collected from seven hawksbill turtles and their corresponding nests at Melaka’s nesting beaches and hatchery site. FSSC was prevalent in the unhatched eggs (n = 32) from the seven study nests, colonising 96.9%. The remaining eggs from the study nests were found to have high hatching success, with a mean of 85.8 ± 10.5% (n = 7). It is unknown if the presence of FSSC contributed directly to embryonic mortality in this study. There are two possible roles of FSSC in sea turtle eggs: as a saprophyte or a primary pathogen. The presence of FSSC in the nest did not always compromise the hatching success of the entire egg clutch. FSSC was not detected in the sand samples of all nests, even though all nests contained Fusarium-colonised eggs. The concentration of FSSC in the sand might influence the infection rate of sea turtle eggs and their hatching success. Best practices for hatchery must be in place to achieve high hatching success for sea turtle conservation.

Personality-dependent nest site selection and nest success during incubation in wild chestnut thrushes

In birds, little is known about how individuals choose nest sites based on their personality traits. Here, we investigate whether a female's personality (activity and breathing rate) can affect patterns of nest site selection at different spatial scales in a wild population of chestnut thrush (Turdus rubrocanus) and determine whether nest site characteristics and female personality traits affect clutch size and nest success during incubation. We found that neither activity nor breathing rate were associated with large-scale nesting habitat variables. At the fine-scale level, more active females chose nest sites with greater nest lateral concealment. Females with higher breathing rates laid smaller clutch sizes than individuals with lower breathing rates. Nests of females with lower breathing rate had higher nest success during incubation. This work highlights the relationships between personality and nest site selection in birds, and the important role of female personality traits in reproductive success.

Minimal shift of eastern wild turkey nesting phenology associated with projected climate change

Climate change may induce mismatches between wildlife reproductive phenology and temporal occurrence of resources necessary for reproductive success. Verifying and elucidating the causal mechanisms behind potential mismatches requires large-scale, longer-duration data. We used eastern wild turkey (Meleagris gallopavo silvestris) nesting data collected across the southeastern U.S. over eight years to investigate potential climatic drivers of variation in nest initiation dates. We investigated climactic relationships with two datasets, one inclusive of successful and unsuccessful nests (full dataset) and another of just successful nests (successfully hatched dataset), to determine whether successfully hatched nests responded differently to weather changes than all nests did. In the full dataset, each 10 cm increase in January precipitation was associated with nesting occurring 0.46–0.66 days earlier, and each 10 cm increase in precipitation during the 30 days preceding nesting was associated with nesting occurring 0.17–0.21 days later. In the successfully hatched dataset, a 10 cm increase in March precipitation was associated with nesting occurring 0.67–0.74 days earlier, and an increase of one unit of variation in February maximum temperature was associated with nesting occurring 0.02 days later. We combined the results of these modeled relationships with multiple climate scenarios to understand potential implications of future climate change on wild turkey nesting phenology; results indicated that mean nest initiation date is projected to change by <0.1 day by 2040–2060. Wild turkey nesting phenology did not track changes in spring green-up timing, which could result in phenological mismatch between the timing of nesting and the availability of resources critical for successful reproduction.

Local food availability and nonbreeding carry-over effects affect breeding propensity and success of a tundra-nesting predator, the Long-tailed Jaeger

Abstract Reproduction of long-distance migrants can be affected by local conditions on the breeding grounds as well as those encountered during the nonbreeding season through carry-over effects. We show that this is true in Long-tailed Jaegers (Stercorarius longicaudus) because individuals that spent less time flying at sea during winter had a high breeding propensity and a reduced pre-laying interval, but breeding propensity and nesting success were also positively associated with food abundance at the breeding site. This seabird switches from a marine to a terrestrial lifestyle to breed in summer in the Arctic, where it primarily feeds on lemmings. We monitored jaeger reproduction and lemming densities on Bylot Island in the Canadian Arctic for 16 years, and we used geolocator to study annual movements. We assessed whether movement parameters (travel distance, migration duration, phenology, and number of flying bouts inferred by saltwater immersions) during the nonbreeding season affected the breeding propensity, phenology, and success of individuals. We also examined whether cyclic lemming fluctuations influenced Long-tailed Jaeger reproduction and whether nesting success affected the phenology of their outbound migration. We found that increased time spent flying during winter and early arrival at the breeding site reduced breeding propensity. Moreover, spending less time flying during winter shortened the pre-laying period, and advancing laying date increased nesting success. Birds may thus face a trade-off to minimize the relative costs associated with arriving too early and breeding too late. Local food availability had a strong effect on reproduction because breeding propensity and nesting success increased sharply with lemming abundance. Failed breeders advanced their outbound migration by 10 days on average compared to successful ones, but migration duration was similar. Therefore, the unpredictability of the highly seasonal Arctic environment, especially fluctuating food abundance, appears to be a strong driver of reproduction that can modulate the strength of carry-over effects.

Corrigendum: Do freshwater turtles use rainfall to increase nest success?

Corrigendum: Do freshwater turtles use rainfall to increase nest success?

Nest Success by a Female Black-Chinned Hummingbird (Archilochus alexandri) with Male-Like Plumage

Nest Success by a Female Black-Chinned Hummingbird (Archilochus alexandri) with Male-Like Plumage

A hierarchical modelling framework for estimating individual‐ and population‐level reproductive success from movement data

Abstract Rapidly advancing animal telemetry technologies paired with new statistical models can provide insight into the behaviour of otherwise unobservable free‐living animals. Changes in behaviour apparent from pairing telemetry with statistical models often occur as animals undertake key life‐history activities, such as reproduction. For many species that are secretive or occupy remote areas, these life‐history events are difficult to detect with conventional survey techniques, and consequently, vital rates are difficult to estimate. We present a hierarchical modelling framework, which integrates movement data observed via animal‐borne telemetry and optional, infrequent survey data, to estimate individual‐ and population‐level reproductive success. The approach combines a mechanistic movement model and survival model, and allows for assessing the effects of hypothesized individual and environmental covariates on reproductive success. We first tested our approach with simulated data, and then applied it to movement data from migratory golden eagles (Aquila chrysaetos) breeding in southcentral Alaska across four breeding seasons. We show that results supported our biological hypotheses that changes in movement coincided with the timing of reproductive failures, and that changes in movement could be used to assess breeding success (and failure) at the individual and population levels. The analysis also provided evidence of inter‐annual variation in population‐level nest success and the timing of nesting failures. This new approach is adaptable to many species that care for young and can be tracked with telemetry devices, and can provide not only individual‐level information useful for testing ecological hypotheses, but estimates of demographic parameters that can directly inform conservation and management if tagged animals are representative of the population.

Annual recruitment is correlated with reproductive success in a smallmouth bass population

Annual recruitment in fish is undoubtedly impacted by a vast number of biotic and abiotic factors. That is especially the case for fish species such as the black bass (species in the genus Micropterus), where there is extended parental care. Although much focus has been given in the past on determining the roles that many of these factors (e.g., temperatures, wind, flow rates, and habitat change) play in determining recruitment among the back basses, little attention has been given to assessing what role reproductive success plays in that determination. To address this question, we conducted a long-term study on two adjacent smallmouth bass (SMB) Micropterus dolomieu Lacepède, 1802 populations in eastern ON to assess the relationship between annual fry cohort size (FCS) (i.e., population-wide reproductive success) and annual recruitment. To measure population-wide annual FCS, we used snorkel surveys to conduct a complete census of nesting SMB males during the spawn from 1990 to 2015. During those surveys, we quantified mating success, determined which nests were successful or not, and calculated the number of independent fry produced each year by summing those numbers across all successful nests. Summer snorkel surveys from 1991 to 2016 assessed annual recruitment through visual counts of age 1+ juveniles. Results demonstrated a highly significant, positive, linear relationship between annual FCS and annual recruitment.

Nest Success of Alligator Snapping Turtles (Macrochelys temminckii) in Louisiana, with Comments on Sources of Mortality

We report nest success for 16 Alligator Snapping Turtle nests oviposited at Black Bayou Lake National Wildlife Refuge in 2008 and 2009. We split each clutch into 2 portions for field and laboratory incubation. The field portion was protected from mammalian depredation. For each nest, we report both pipping and hatching success. Our total observed levels of pipping and hatching success were 55.9% and 47.7%, respectively. We obtained a hatching success rate of 85.8% in the lab. Reasons for the difference in hatching success between the field and lab included both abiotic and biotic factors in the nest environment, such as flooding, temperature, and invertebrate predators.

First Successful Nesting of Black Oystercatchers among Endangered California Least Terns along the West Coast of North America

First Successful Nesting of Black Oystercatchers among Endangered California Least Terns along the West Coast of North America

Reproductive asynchrony within social groups of female eastern wild turkeys.

Coordination in timing of reproduction is driven by multiple ecological and sociobiological processes for a wide array of species. Eastern wild turkeys (Meleagris gallopavo silvestris) use a male dominance polygynous mating system, where males communicate with females via elaborate courtship displays and vocalizations at display sites. Most females prefer to mate with dominant males; therefore, asynchronous breeding and nesting may occur which can disproportionately influence individual fitness within breeding groups. For female wild turkeys, there are reproductive advantages associated with earlier nesting. As such, we evaluated reproductive asynchrony within and between groups of GPS-tagged female eastern wild turkeys based on timing of nest initiation. We examined 30 social groups with an average of seven females per group (range 2-15) during 2014-2019 in west central Louisiana. We found that the estimated number of days between first nest initiation across females within groups varied between 3 and 7 days across years, although we expected 1-2 days to occur between successive nesting attempts of females within groups based on observations of captive wild turkeys in the extant literature. The number of days between successive nest attempts across females within groups was lower for successful than failed attempts, and nests with an average of 2.8 days between initiation of another nest were more likely to hatch. Our findings suggest that asynchronous reproduction may influence reproductive success in female wild turkeys.

Successful nest defence of Eurasian reed warblers Acrocephalus scirpaceus against the little bittern Ixobrychus minutus

The cost–benefit approach to nest defence behaviour is based on an assumption that parents are able to distract potential predators away from their nest. However, this assumption has received little support from direct observations as predator-prey encounters near nests are rarely recorded, especially in small passerines. Here, we describe two observations of little bitterns appearing near nests of Eurasian reed warblers containing nestlings and eggs, respectively. In both cases parental birds showed anti-predatory behaviour, which was much more vigorous at the nestling stage than at the egg stage. During both observations, the heron finally flew away and did not attack the nest content, indicating that nest defence behaviour of small passerines may be effective.

Use of Airborne Laser Scanning to assess effects of understorey vegetation structure on nest‐site selection and breeding performance in an Australian passerine bird

AbstractIn wild bird populations, the structure of vegetation around nest‐sites can influence the risk of predation of dependent offspring, generating selection for nest‐sites with vegetation characteristics associated with lower predation rates. However, vegetation structure can be difficult to quantify objectively in the field, which might explain why there remains a general lack of understanding of which characteristics are most important in determining predation rates. Airborne laser scanning (ALS) offers a powerful means of measuring vegetation structure at unprecedented resolution. Here, we combined ALS with 11 years of breeding data from a wild population of superb fairy‐wrens Malurus cyaneus in southeastern Australia, a species which nests relatively close to the ground and has high rates of nest and fledgling predation. We derived structural measurements of understorey (0–8 m) vegetation from a contiguous grid of 30 × 30 m resolution cells across our c. 65 hectares study area. We found that cells with nests (nest‐cells) differed in their understorey vegetation structure characteristics compared to unused cells, primarily in having denser vegetation in the lowest layer of the understorey (0–2 m; the ‘groundstorey’ layer). The average height of understorey vegetation was also lower in cells with nests than in those without nests. However, relationships between understorey vegetation structure characteristics and breeding performance were mixed. Nest success rates decreased with higher volumes of groundstorey vegetation, as did fledgling survival rates, though only in nest‐cells with lower height vegetation. Our results indicate that ALS can identify vegetation characteristics relevant for superb fairy‐wren nest‐site selection, but that nesting preferences are not beneficial under current predation pressures. The study illustrates the potential for using ALS to investigate how ecological conditions affect behaviour and life‐histories in wild animal populations.

Nest attendance, incubation constancy, and onset of incubation in dabbling ducks.

In birds, parents must provide their eggs with a safe thermal environment suitable for embryonic development. Species with uniparental incubation must balance time spent incubating eggs with time spent away from the nest to satisfy self-maintenance needs. Patterns of nest attendance, therefore, influence embryonic development and the time it takes for eggs to hatch. We studied nest attendance (time on the nest), incubation constancy (time nests were at incubation temperatures), and variation in nest temperature of 1,414 dabbling duck nests of three species in northern California. Daily nest attendance increased from only 1-3% on the day the first egg was laid to 51-57% on the day of clutch completion, and 80-83% after clutch completion through hatch. Variation in nest temperature also decreased gradually during egg-laying, and then dropped sharply (33-38%) between the day of and the day after clutch completion because increased nest attendance, particularly at night, resulted in more consistent nest temperatures. During the egg-laying stage, nocturnal nest attendance was low (13-25%), whereas after clutch completion, nest attendance was greater at night (≥87%) than during the day (70-77%) because most incubation recesses occurred during the day. Moreover, during egg-laying, nest attendance and incubation constancy increased more slowly among nests with larger final clutch sizes, suggesting that the number of eggs remaining to be laid is a major driver of incubation effort during egg-laying. Although overall nest attendance after clutch completion was similar among species, the average length of individual incubation bouts was greatest among gadwall (Mareca strepera; 779 minutes), followed by mallard (Anas platyrhynchos; 636 minutes) and then cinnamon teal (Spatula cyanoptera; 347 minutes). These results demonstrate that dabbling ducks moderate their incubation behavior according to nest stage, nest age, time of day, and clutch size and this moderation likely has important implications for egg development and overall nest success.

Fight or flight: Eastern wild Turkey repeatedly defends nest against raccoon

Eastern wild turkeys (Meleagris gallopavo silvestris) are an economically and culturally important species throughout eastern and central North America. Eastern wild turkey nests are predated by a suite of predators, providing sustenance for those predators but also potentially adding to recent turkey population declines. While studies of wild turkey nest success and nest predation rates are common, many rely on artificial nests which fail to account for the defensive capabilities of nesting hens. Direct observation of attempted and successful predation events are largely absent from the literature, but needed to understand these interspecific interactions. Following the chance discovery of an eastern wild turkey nest we placed two camera traps overlooking the nest. The camera traps recorded six attempted nest raids by a raccoon (Procyon lotor), of which only once did the raccoon appear to steal an egg. The remaining five attempts were fended off by the hen, which puffed her feathers and defended the nest. We conclude that hens may be capable of defending their nests against attempted predation events by raccoons, but additional research is needed to determine if this hen's defensive capacity is typical and whether other predators are more successful at raiding nests.

Lesser prairie‐chicken habitat selection and survival relative to a wind energy facility located in a fragmented landscape

The overlap of renewable wind energy with the range of lesser prairie‐chickens Tympanuchus pallidicinctus raises concern of population declines and habitat loss. Lesser prairie‐chickens are adversely affected by landscape change; however, it is unclear how this species may respond to wind energy development. Therefore, managers and wind energy developers are currently tasked with making management or siting recommendations of future wind energy facilities based on lesser prairie‐chicken behavioral responses to other forms of anthropogenic development or responses of other grouse species to wind energy development. The current strategy of siting wind turbines in cultivated cropland within lesser prairie‐chicken range has not been evaluated for its effectiveness at minimizing potential adverse impacts. We captured 60 female and 66 male lesser prairie‐chickens from leks located along a gradient from wind turbines in southern Kansas, USA from 2017–2021. Over the study period, we collected lesser prairie‐chicken location data and demographic information to evaluate resource selection, movement, and demography relative to environmental predictors and metrics associated with the wind energy facility. Lesser prairie‐chickens used habitats in close proximity to wind turbines, provided that turbine density was low; however, avoidance associated with cultivated cropland appeared to be more predictive than the presence of wind turbines. We observed movement between turbines suggesting that wind turbines did not act as a barrier to local movements. We did not detect an influence of wind turbines on nest success or individual survival during breeding or non‐breeding periods, a relationship that is consistent among multiple grouse species using habitats near wind energy infrastructure. Additional research is necessary to evaluate impacts associated with wind energy development in intact lesser prairie‐chicken habitats, but placing wind turbines in cultivated croplands or other fragmented landscapes appears to be an important siting measure when considering wind energy facility siting across the lesser prairie‐chicken range.

Waterfowl distribution and productivity in the Prairie Pothole Region of Canada: tools for conservation planning

AbstractSpecies conservation requires an understanding of the factors and interactions affecting species distribution and behavior, habitat availability and use, and corresponding vital rates at multiple temporal and spatial scales. Opportunities to investigate these relationships across broad geographic regions are rare. We combined long‐term waterfowl population surveys, and studies of habitat use and breeding success, to develop models that identify and incorporate these interactions for upland‐nesting waterfowl in the Prairie Pothole Region (PPR) of Canada. Specifically, we used data from the annual Waterfowl Breeding Population and Habitat Survey (1961–2009) at the survey segment level and associated habitat covariates to model and map the long‐term average duck density across the Canadian PPR. We analyzed nest location and fate data from approximately 25,000 duck nests found during 3 multi‐year nesting studies (1994–2011) to model factors associated with nest survival and habitat selection through the nesting season for the 5 most common upland nesting duck species: mallard (Anas platyrhynchos), gadwall (Mareca strepera), blue‐winged teal (Spatula discors), northern shoveler (Spatula clypeata), and northern pintail (Anas acuta). Duck density was highly variable across the Canadian PPR, reflecting positive responses to local wetland area and count, and amounts of cropland and grassland, a regional positive response to latitude, and a negative response to local amounts of tree cover. Nest survival was affected by temporal and spatial variables at multiple scales. Specifically, nest survival demonstrated interactive effects among species, nest initiation date, and nesting cover type and was influenced by relative annual wetness, population density, and surrounding landscape composition at landscape scales, and broad geographic gradients (east‐west and north‐south). Likewise, species‐specific probability of nest habitat selection was influenced by timing of nest initiation, population density, relative annual wetness, herbaceous cover, and tree cover in the surrounding landscape, and location within the Canadian PPR. We combined these models, with estimates of breeding effort (nesting, renesting, and nest attempts) from existing literature, in a stochastic conservation planning model that estimates nest distribution and success given spatiotemporal variation in duck density, habitat availability, and influential covariates. We demonstrate the use of this model by examining various conservation planning scenarios. These models allow estimation of local, landscape, and regional influence of conservation investments and other landscape changes on the productivity of breeding duck populations across the PPR of Canada. These models lay the groundwork for the incorporation of conservation delivery costs for full return‐on‐investment analyses and scenario analyses of climate, habitat, and land use change in regional and continental population models.