Predation is an important cause of nest failure for many birds and has shaped the life‐history characteristics of many species, especially ground‐nesting shorebirds. We examined nesting success, causes of clutch failure and nest survival in relation to variation in substrate characteristics in a colour‐marked population of Western Snowy Plovers Charadrius alexandrinus nivosus breeding on riverine gravel bars in coastal northern California. Plovers experienced higher nesting success on gravel bars than on nearby beaches, which were characterized by more homogeneous, sandy substrates. On gravel bars, Plovers nested in habitats characterized by large, heterogeneous substrates, with more egg‐sized stones, compared with random sites. Egg crypsis, as indexed by time required of a naïve observer to detect a nest, increased with number of egg‐sized substrates. Nest survival correlated negatively with heterogeneity of substrates and positively with the number of egg‐sized stones. Consistently high nesting success of Plovers on gravel bars indicates that this high‐quality habitat deserves special management considerations given the species’ threatened status.

Habitat quality, as indexed by the reproductive success of individuals, can greatly influence population growth, especially for rare species near the limits of their range. Along the Pacific coast, the Snowy Plover (Charadrius alexandrinus nivosus) is a threatened species that, in recent years, has been breeding on both riverine gravel bars and ocean beaches in northern California. From 2001 to 2009, we compared the habitat characteristics, breeding phenology, reproductive success, and abundance of Western Snowy Plovers occupying these two habitats. Similar percentages of yearling and adult plovers returned to gravel bars and beaches, but plovers breeding on gravel bars arrived and initiated first clutches 2–3 weeks later than those breeding on beaches. Despite this delay, however, the mean annual fledging success of plovers on gravel bars (1.4 ± 0.4 [SD]) was double that on beaches (0.7 ± 0.3). Differences in cumulative reproductive success produced a stronger pattern. By their sixth year, males on gravel bars had fledged 14.5 ± 2.1 chicks, more than four times the number of young fledged by males on beaches (3.3 ± 3.1). Over 9 years, local population size decreased by about 75%, coincident with a shift in breeding distribution away from high‐quality gravel bars to ocean beaches. This unexpected population decline and shift to poorer quality beaches may have been related to occasional low survival of plovers that over‐winter exclusively on beaches in our study area. Consistently low productivity of plovers breeding on ocean beaches suggests the need for intensified management to ameliorate the negative impacts of predation and human activity on the recovery of this population.

No abstract

Gobbling call-count surveys have been frequently used as a means for monitoring distributions and population trends of eastern wild turkeys (Meleagris gallopavo silvestris). However, gobbling activity can be highly variable and potentially leads to biased estimates if detection probability is left unaccounted for. Occupancy modeling based on detection-nondetection data offers an effective way of exploring changes in species distribution and provides logistical flexibility with sampling design. Recent advances in occupancy modeling have enabled detection probability and inferences about occupancy dynamics to be estimated from transect sampling designs with spatially replicated survey stations, similar to those of gobbling call-count surveys. We analyzed data collected from 1,815 gobbling call-count surveys in northern Wisconsin, USA, 2014-2017, to compare multiseason correlated-replicate occupancy models to standard multiseason models. Model selection results strongly supported multiseason correlated-replicate models (Σw i = 1.00) over standard multiseason occupancy models. We observed evidence for spatial autocorrelation in local occupancy-probability of local availability was lower when turkeys were unavailable at the previous station (θ = 0.18 ± 0.07 [SE]) compared with when turkeys were available ( ′ θ = 0.79 ± 0.13). Probability of detection was imperfect and varied by time of day (β = −0.503) and wind speed (β = −0.362). Turkeys occurred throughout a variety of habitat conditions, but occupancy was greatest (ψ = 0.990 ± 0.03) along survey routes with 40-60% forest cover. We fit simulated data to standard occupancy models and correlated replicate models and found occupancy and detection estimates were underestimated by as much as 10% with standard occupancy models, but bias was negligible under the correlated replicate modeling approach. Our findings indicate that transect sampling designs that account for spatial correlation among adjacent survey stations can yield improved estimates of detection and occupancy, and such sampling designs could lead to greater ecological interest in factors that influence species occurrence and patterns of habitat use. Gobbling call-count surveys in conjunction with occupancybased modeling may be useful for assessing reintroduced or natural expanding wild turkey populations at the edge of their range. Additionally, we suggest the combination of gobbling surveys and occupancy modeling is useful for evaluating habitat-occurrence relationships across large-scale landscapes or statebased wild turkey management units.

Translocations have become an increasingly valuable tool for conservation in recent years, but assessing the successfulness of translocations and identifying factors that contribute to their success continue to challenge biologists. As a unique class of translocation, population reinforcements have received relatively little attention despite representing a substantial portion of translocation programs. Here, we conducted population viability analyses to quantify the effects of 216 reinforcement scenarios on the long‐term viability of four populations of Greater Prairie‐Chickens (Tympanuchus cupido pinnatus) in Wisconsin, USA, and used multiple linear regression to identify factors that had the greatest relative influence on population viability. We considered reinforcements from outside of the study area in addition to translocations among Wisconsin populations. We observed the largest decreases in site‐specific extinction probability and the largest increases in the number of sites persisting for 50 years when more vulnerable populations were targeted for reinforcement. Conversely, reinforcing the most stable sites caused the greatest reduction in regional extinction probability. We found that the number of translocated hens was a comparatively poor predictor of changes in long‐term population viability, whereas the earlier onset of reinforcement was consistently associated with the greatest increases in viability. Our results highlight the value of evaluating alternative reinforcement strategies a priori and considering the effects of reinforcement on metrics of long‐term population persistence.