Colored plastic and metal leg bands do not affect survival of Piping Plover chicks

ABSTRACT Leg bands are commonly used to mark shorebird chicks as young as 1‐d old, but little is known about the possible impacts of bands on survival of prefledging shorebirds. We used a mark‐recapture framework to assess the impact of bands and banding‐related disturbance on prefledging survival in a federally endangered population of Piping Plovers (Charadrius melodus) breeding in the Great Lakes region from 2000 to 2008. We banded approximately 96% of all surviving chicks hatched prior to fledging, typically between 5 and 15 d of age. We used a multistate approach in program MARK whereby individuals contributed data as unbanded chicks before capture (N= 1073) and as banded chicks afterward (N= 780). The cumulative probability of surviving through 24 d of age was 0.63 and did not differ between banded and unbanded chicks. In addition, we found a positive effect of banding‐related disturbance on survival up to 3 d following banding (β= 0.60 CI: 0.17–1.02), possibly due to increased postbanding vigilance on the part of chicks and adults. Our results indicate that banding has no detrimental effect on survival of Piping Plover chicks prior to fledging and that current capture and banding methods are appropriate for this endangered species.     

Effects of repeated investigator handling of Leach's Storm‐Petrel chicks on growth rates and the acute stress response

Disturbance during development may have lasting effects on the growth rates and stress physiology of birds. Although repeated handling by researchers is often necessary, the possible effects of such handling on the development of semi‐altricial young are unclear. We examined the effect of daily handling on growth rates and plasma corticosterone levels of Leach's Storm‐Petrel (Oceanodroma leucorhoa) chicks on Kent Island in the Bay of Fundy, New Brunswick, Canada, during the 2011 nesting season. From post‐hatch day 7 to post‐hatch days 14–36, birds in the experimental group were extracted from burrows and measured (wing, tarsus, and mass) for ～3 min every day, whereas birds in the control group were left undisturbed. After the treatment period, blood was collected from birds in both groups within 3 min of initially reaching into burrows (baseline) and after a 30‐min restraint stress test to assess the effect of early life disturbance on programming of the hypothalamic‐pituitary‐adrenal (HPA) axis. A second acute restraint stress test was conducted three weeks after the end of the treatment period to investigate possible longer term effects of early life disturbance. Growth rates of wings and tarsi were similar for handled chicks (N = 18) and non‐handled control chicks (N = 21), as were baseline and 30‐min acute restraint stress‐induced corticosterone levels. As also reported in previous studies of other altricial and semi‐altricial species, older chicks (42–64 d old) had higher plasma corticosterone levels than younger chicks (21–43 d old) after acute restraint stress tests, reflecting delayed development of the HPA axis. The age‐related increase in HPA axis sensitivity observed prior to fledging could facilitate foraging and predator avoidance behaviors while minimizing exposure to high levels of corticosterone earlier in development. Overall, we found no evidence that repeated disturbance influenced either growth rates or HPA axis programming of Leach's Storm‐Petrel chicks.     

Chick mortality leads to male‐biased sex ratios in endangered Great Lakes Piping Plovers

Few investigators have studied the offspring sex ratios of monomorphic shorebirds because visually determining the sex of juveniles is not possible. We investigated the ontogeny of an observed male‐biased adult sex ratio in the federally endangered Great Lakes population of Piping Plovers (Charadrius melodus). We determined sex ratios at hatching, banding ( = 9.0 d old), and fledging (23 d old) to determine if the bias arises during the pre‐fledging period and, if so, at what stage. For three consecutive years (2012–2014), we used a molecular technique to determine the sex of 307 chicks and followed individuals to a stage where survival to fledging could be inferred. Within fully‐sexed broods at hatching, the average proportions of male chicks (2012–2014) were 0.47, 0.58, and 0.54, respectively. At banding, the sex ratio remained unbiased in 2012 (0.51), but was male‐biased in 2013 (0.59) and 2014 (0.57). Overall, the sex ratio did not differ significantly from parity at fledging in 2012, but did differ during 2013 (P = 0.01) and 2014 (P = 0.03). Using logistic regression models fit using Bayesian inference, we found strong support for a sex effect on chick survival to fledging age, with higher male than female survival (μ_male = 0.83 [95% credible interval: 0.75–0.90]; μ_female = 0.71 [0.61–0.80]). These results suggest that the male‐biased adult sex ratio in Piping Plovers arises, in part, due to differential survival during the pre‐fledging period. This difference did not result from female chicks hatching later in the season or weighing less at banding than male chicks, factors that could potentially affect the likelihood of survival. Future investigations into possible behavioral‐ or weather‐related influences on sex‐specific survival are needed. Our results have important implications for (1) identifying management efforts needed to increase recruitment given female‐biased chick mortality, and (2) conducting population viability analyses, which frequently assume an unbiased fledgling sex ratio.     

Accuracy of nest fate classification and predator identification from evidence at nests of Least Terns and Piping Plovers

For federally listed species such as Least Tern Sternula antillarum and Piping Plover Charadrius melodus, correct determination of nest fates and causes of nest failure is crucial for understanding population dynamics and improving monitoring programmes. We used video cameras to evaluate nest fate misclassification rate and to identify factors that may cause researchers monitoring nests at different intervals to classify Least Tern and Piping Plover nest fates incorrectly. During the 2013–2015 breeding seasons, we installed miniature surveillance cameras at 65 of 294 Least Tern and 89 of 551 Piping Plover nests under observation on the Missouri River in North Dakota. Nest fates were assigned in the field from remains found at the nest‐site and then again by an independent researcher who reviewed camera footage. We used ordinal logistic regressions to examine whether monitoring interval, clutch age or temporal factors influenced a correct, partially misclassified (probable successful in the field vs. successful by camera) or misclassified nest fate classification. During a 7‐day monitoring interval between visits, 45% of nests were partially and 27.5% were fully misclassified. The percentage of partially (20%) and fully (8.0%) misclassified nests decreased with a more intensive (3‐day) monitoring schedule. Researchers were also less likely to correctly classify nest fates for Least Terns than for Piping Plovers, and as clutch age and monitoring interval increased for both species. Furthermore, causes of failure (e.g. predators, weather) as determined from field evidence vs. video disagreed for 53.5% of nests. The ability to identify accurately nest fate and cause of nest failure will facilitate a better understanding of factors that limit productivity and will lead to better informed management decisions for improving nest survival.     

Golden Plover Pluvialis apricaria breeding success on a moor managed for shooting Red Grouse Lagopus lagopus

Capsule The best estimate of breeding success was a mean of 0.57 fledglings per pair, which when combined with adult survival rates, successfully explained the observed population trend.

Aims To quantify Golden Plover breeding success on a moor managed for shooting Red Grouse Lagopus lagopus.

Methods An intensive study recorded the fate of individual Golden Plover nests and, using radiotelemetry, chicks. The factors associated with mortality were examined, allowing the construction of a model of breeding success. Adult survival was estimated from return rates of colour-ringed birds.

Results Estimated rates of daily nest survival during laying (0.8636) were significantly lower than during incubation (0.9913). The daily survival rate of chicks less than nine days (0.8868) was significantly lower than for older chicks (0.9792). A population model based on these parameters overestimated the rate of nest losses, but accurately described brood survival and fledging success. Although predation rates were low, poor survival of young chicks through starvation or exposure suggest other factors were limiting breeding success at the study site.

Conclusions Predation rates of Golden Plover nests and chicks can be low on moorlands managed for shooting Red Grouse. However, in the absence of predation, other factors may still reduce chick survival and limit breeding success.     

Estimating flight height and flight speed of breeding Piping Plovers

Collisions with wind turbines are an increasing conservation concern for migratory birds that already face many threats. Existing collision‐risk models take into account parameters of wind turbines and bird flight behavior to estimate collision probability and mortality rates. Two behavioral characteristics these models require are the proportion of birds flying at the height of the rotor swept‐zone and the flight speed of birds passing through the rotor swept‐zone. In recent studies, investigators have measured flight height and flight speed of migrating birds using fixed‐beam radar and thermal imaging. These techniques work well for fixed areas where migrants commonly pass over, but they cannot readily provide species‐specific information. We measured flight heights of a nesting shorebird, the federally threatened Piping Plover (Charadrius melodus), using optical range finding and measured flight speed using videography. Several single‐turbine wind projects have been proposed for the Atlantic coast of the United States where they may pose a potential threat to these plovers. We studied Piping Plovers in New Jersey and Massachusetts during the breeding seasons of 2012 and 2013. Measured flight heights ranged from 0.7 to 10.5 m with a mean of 2.6 m (N = 19). Concurrent visually estimated flight heights were all within 2 m of measured heights and most within 1 m. In separate surveys, average visually estimated flight height was 2.6 m (N = 1674) and ranged from 0.25 m to 40 m. Average calculated flight speed was 9.30 m/s (N = 17). Optical range finding was challenging, but provided a useful way to calibrate visual estimates where frames of reference were lacking in the environment. Our techniques provide comparatively inexpensive, replicable procedures for estimating turbine collision‐risk parameters where the focus is on discrete nesting areas of specific species where birds follow predictable flight paths.     

Effects of color banding, radio tagging, and repeated handling on the condition and survival of Lapwing chicks and consequences for estimates of breeding productivity

ABSTRACT.   Color bands and radio tags are widely used to facilitate individual recognition and relocation of precocial chicks in studies of prefledging survival. However, the accuracy of data collected and subsequent estimates of survival rates rely on the assumption that such techniques do not affect the parameters under study. We compared the body condition and survival of color-banded and radio-tagged Lapwing ( Vanellus vanellus ) chicks with noncolor-banded and nonradio-tagged individuals using a 10-year dataset ( N = 3174 chicks, with 205 color banded and 700 radio tagged). Color bands did not adversely affect chicks. However, radio-tagged chicks and their untagged broodmates were handled more frequently because these broods were more readily encountered than those without a tagged member. Chicks disturbed and handled more frequently had lower body condition indices and higher mortality rates. Simulations of the impact of tagging and handling on breeding productivity under two scenarios indicated a 26% reduction in productivity in situations where nest and chick survival rates were low (as in our study), but only a 7% reduction in productivity for a simulated population with the higher levels of nest and chick survival associated with a stable population. The frequent disturbance associated with radio-tracking and recapturing chicks, rather than the attachment of a tag or physical handling of chicks, may affect body condition. Frequent handling and disturbance may affect body condition by reducing foraging time, increasing stress levels, or increasing predation risk. Because our results suggested that the negative impact of handling could last up to a week, we recommend that investigators avoid disturbance of shorebird chicks more frequently than every 8 d.     

Male‐skewed adult sex ratio,survival, mating opportunity and annual productivity in the Snowy Plover Charadrius alexandrinus

Sex differences in adult mortality may be responsible for male‐skewed adult sex ratios and male‐skewed parental care in some birds. Because a surplus of breeding males has been reported in serially polyandrous populations of Snowy Plover Charadrius alexandrinus, we examined sex ratio, early‐season nesting opportunities, adult survival and annual reproductive success of a Snowy Plover population at Monterey Bay, California. We tested the hypotheses that male adult survival was greater than female survival and that a sex difference in adult survival led to a skewed adult sex ratio, different mating opportunities and different annual productivity between the sexes. Virtually all females left chicks from their first broods to the care of the male and re‐nested with a new mate. As a result, females had time to parent three successful nesting attempts during the lengthy breeding season, whereas males had time for only two successful attempts. Among years, the median population of nesting Plovers was 96 males and 84 females (median difference = 9), resulting in one extra male per eight pairs. The number of potential breeders without mates during the early nesting period each year was higher in males than in females. Adult male survival (0.734 ± 0.028 se) was higher than female survival (0.693 ± 0.030 se) in top‐ranked models. Annually, females parented more successful clutches and fledged more chicks than their first mates of the season. Our results suggest that in C. alexandrinus a sex difference in adult survival results in a male‐skewed sex ratio, which creates more nesting opportunities and greater annual productivity for females than for males.     

Breeding sites and winter site fidelity of Piping Plovers wintering in The Bahamas,a previously unknown major wintering area

Most of the known wintering areas of Piping Plovers (Charadrius melodus) are along the Atlantic and Gulf coasts of the United States and into Mexico, and in the Caribbean. However, 1066 threatened/endangered Piping Plovers were recently found wintering in The Bahamas, an area not previously known to be important for the species. Although representing about 27% of the birds counted during the 2011 International Piping Plover Winter Census, the location of their breeding site(s) was unknown. Thus, our objectives were to determine the location(s) of their breeding site(s) using molecular markers and by tracking banded individuals, identify spring and fall staging sites, and examine site fidelity and survival. We captured and color‐banded 57 birds in January and February 2010 in The Bahamas. Blood samples were also collected for genetic evaluation of the likely subspecies wintering in The Bahamas. Band re‐sightings and DNA analysis revealed that at least 95% of the Piping Plovers wintering in The Bahamas originated on the Atlantic coast of the United States and Canada. Re‐sightings of birds banded in The Bahamas spanned the breeding distribution of the species along the Atlantic coast from Newfoundland to North Carolina. Site fidelity to breeding and wintering sites was high (88–100%). Spring and fall staging sites were located along the Atlantic coast of the United States, with marked birds concentrating in the Carolinas. Our estimate of true survival for the marked birds was 0.71 (95% CI: 0.61–0.80). Our results indicate that more than one third of the Piping Plover population that breeds along the Atlantic coast winters in The Bahamas. By determining the importance of The Bahamas to the Atlantic subspecies of Piping Plovers, future conservation efforts for these populations can be better focused on where they are most needed.     

Taming parent‐reared orange‐winged Amazon parrots by neonatal handling

Tameness in parrots is often achieved by artificial rearing, in which chicks are typically removed from parents, fed a liquified or semi‐liquified diet by oral gavage and maintained in thermally controlled brooders until they are grown. As an alternate means of rearing birds, we tested whether occasional neonatal human handling of parent‐reared chicks might produce tameness while reducing the risk of sexual imprinting on humans. Orange‐winged Amazon chicks (Amazona amazonica) were incubated and hatched by wild‐caught parents, then were temporarily removed from the nest box, and handled at various times during the nestling period. In Trial 1, handled chicks (n = 6) were handled from days 10 to 39 of age for 10–20 min/day and from 40 days to fledging (days 56–/57) for 20–30 min/day. Nonhandled chicks (n = 4) were handled only to record body weight and provide medication, as needed. After fledging, chicks were evaluated for tameness, e.g., by their willingness to approach the handler, perch on a finger, be touched on the head, and by their respiratory rate in the presence of the handler. Handled birds differed significantly in all indices of tameness. In Trial 2, handled chicks were handled for 30 min, four times/week either from days 15 to 36 (n = 3) or 35 to 56 (n = 3); results were similar to Trial 1. Chicks handled later tended to be slightly tamer than those handled earlier. In both trials, the amount of time that handled chicks were in contact with humans was less than 2% of the time they spent with conspecifics. It is therefore unlikely that these chicks imprinted either filially or sexually on humans, although this has not been experimentally tested. While continued handling is likely necessary to maintain tameness, these results support the concept that neonatal handling of parent‐raised parrots provides a low‐labor and low‐technology alternative to artificial rearing as a means of initially taming birds, thereby improving their adaptation to life in captivity. Zoo Biol 18:177–187, 1999. © 1999 Wiley‐Liss, Inc.     

Breeding ecology of Red‐faced Cormorants in the Pribilof Islands,Alaska

ABSTRACT Red‐faced Cormorants (Phalacrocorax urile) are North Pacific endemics recognized as a vulnerable species, but little is known about their breeding ecology. We studied Red‐faced Cormorants on St. Paul Island, Alaska, from 1975 to 2009, with more detailed data collected in 2004 and 2005. Mean clutch sizes in 2004 (3.2 ± 0.8 [SD] eggs) and 2005 (3.1 ± 0.8 eggs) were similar to the long‐term average (2.9 ± 0.3 eggs from 1976 to 2009). The mean laying interval in 2004 and 2005 was 2.15 ± 0.80 d (N= 407), and the mean egg period (number of days between laying of an egg and hatching) was 31.1 ± 1.4 d (N= 158). Approximately 64 ± 17% of eggs hatched during the period from 1975 to 2009. The mean number of chicks per nest in 2004 and 2005 was 2.8 ± 0.8 (N= 232), and the mean number of fledglings per initiated nest in all years was 1.22 ± 0.52. Chicks fledged 46 to 66 d posthatching. In 2004 and 2005, the primary causes of egg loss were predation by Arctic foxes (Vulpes lagopus) and destruction of eggs and abandonment of nests due to storms. Starvation was the primary cause of nestling mortality in both years. Because chicks are dependent on parents to provide food for over 45 d, consistent near‐shore foraging opportunities must be available. From 1975 to 2009, Red‐faced Cormorants experienced only 1 yr of complete reproductive failure (1984). The consistent reproductive success of Red‐faced Cormorants suggests that conditions may be relatively stable for this species on St. Paul Island, or that the variability in their breeding ecology (e.g., phenology, clutch sizes, and incubation strategies) provides the flexibility needed to successfully fledge some chicks nearly every year.     

Nest survival and productivity of the critically endangered Sociable Lapwing Vanellus gregarius

The Sociable Lapwing Vanellus gregarius is a critically endangered species, probably declining from 5000 pairs to 500 pairs in 11 years. Fieldwork was conducted at two sites in Kazakhstan, May–August 2004, to identify causes of the species’ decline. In total, 58 nests and a minimum of 36 broods in 16 colonies were found: colonies consisted of 1–8 nests that were on average 154 m apart, with 2.1 km between colonies. Although classified as biparental, the total proportion of time both parents spent incubating was low (77 ± 2% se, n = 13 nests). Daily survival rates (Mayfield method) were very low during incubation (0.943 ± 0.009 se) but high during the chick stage (0.986 ± 0.004 se); incubation and chick‐stage durations were found to be 28.5 and 29 days, respectively, so that the overall probability of any breeding attempt fledging chicks was 0.124 (0.055–0.274 95% confidence interval). A breeding attempt that produced fledglings, fledged 2.2 ± 0.2 se chicks (n = 26) on average. Observed productivity predicted the population decline over the last 11 years well (using the maximum number of nesting attempts per pair of 1.4 that could have occurred in this study, and assuming an adult and first‐year survival rate of 0.74 and 0.60, respectively, based on the means for Northern Lapwing Vanellus vanellus and Golden Plover Pluvialis apricalia). Nest survival during incubation (controlling for colony effects) may have been longer for nests in predominantly Artemisia rather than grass habitat. Mean nest survival for a colony was higher in areas with more bare ground and more nest predators, suggesting that predators were relatively unimportant in nest (egg or chick) mortality, but was lower in areas with high numbers of cattle, suggesting that trampling was important (64% of known‐cause nest failures, n = 11, were trampled). Nests were preferentially sited in areas of Artemisia, where there was greater dung abundance, and probably shorter vegetation, suggesting that highly grazed vegetation is important for nesting. Chicks preferentially selected areas with a lower percentage of bare ground and possibly taller vegetation, suggesting that more vegetated areas are important for chicks. The results suggest that low egg survival due to nesting in areas of high grazer density may be responsible for the Sociable Lapwing's decline. Although grazers may create suitable vegetation for initial nesting, if those grazers remain at high density as in anthropogenic systems then they may reduce nest survival, probably through trampling. Experimentally maintaining grazing early but reducing it later in the breeding season is the logical first step in managing the species to increase egg survival and so to increase productivity.     

Habitat selection,diet and food availability of European Golden Plover Pluvialis apricaria chicks in Swedish Lapland

Fennoscandian alpine tundra habitats support large numbers of breeding waders, but relatively little is known about their breeding ecology despite the fact that this habitat is threatened by climate change. We studied habitat selection, diet and prey availability of European (Eurasian) Golden Plover Pluvialis apricaria chicks at the Vindelfjällen Nature Reserve, Ammarnäs, Sweden. Information from 22 chicks tracked using radio‐transmitters was analysed. By analysing 149 faecal samples, four main prey taxa were identified, Coleoptera (40%), Bibionidae (31%), Hymenoptera (13%) and Tipulidae (10%). We found that chicks switched from feeding on Tipulidae to feeding on Bibionidae as they grew, and that this switch coincided with a shift from the use of the habitat where Tipulidae were abundant (alpine meadow/heathland) to the use of the habitat were Bibionidae were abundant (Willow shrub). Although chicks track food availability to some extent, the link between prey availability and habitat use was not perfect, indicating that additional factors other than food abundance, such as shelter from predators, determine habitat selection. Bibionidae are an important prey for Golden Plover chicks as it is the only prey group that has a late summer flush in abundance, in contrast to the general decline of total arthropod biomass during the chick‐rearing period. However, Bibionidae imagoes only occurred in 2011 and were virtually absent in 2013, which relates to the species’ ecology with 2‐ to 5‐year cycles in mass occurrence. Extreme annual variation in an essential food source such as Bibionidae imagoes might have an important effect on the condition and survival of Golden Plover chicks, an important subject for future studies. The foraging conditions for Golden Plover chicks in Fennoscandia appear to be different to those in the UK, where the chicks rely mainly on a Tipulidae flush only.     

Use of Implanted Radiotransmitters to Estimate Survival of Greater Sage-Grouse Chicks

ABSTRACT Reduced chick survival has been implicated in declines of greater sage-grouse (Centrocercus urophasianus) populations. Because monitoring survival of unmarked sage-grouse chicks is difficult, radiotelemetry may be an effective technique to estimate survival rates, identify causes of mortality, and collect ecological data. Previous studies have used subcutaneous implants to attach radiotransmitters to hatchlings of several species of birds with precocial young. Previous researchers who used subcutaneous implants in free-ranging populations removed chicks from the capture location and implanted transmitters at an alternate site. Because logistics precluded removing newly hatched greater sage-grouse chicks from the field, we evaluated a method for implanting transmitters at capture locations. We captured 288 chicks from 52 broods and monitored 286 radiomarked chicks daily for 28 days following capture during May and June 2001–2002. Two (>1%) chicks died during surgery and we did not radiomark them. At the end of the monitoring period, 26 chicks were alive and 212 were dead. Most (98%, 207/212) radiomarked chick mortality occurred < 21 days posthatch and predation (82%, 174/212) was the primary cause of death. Necropsies of 22 radiomarked chicks did not indicate inflammation or infection from implants, and they were not implicated in the death of any chicks. Fate of 48 chicks was unknown because of transmitter loss (n = 16), radio failure (n = 29), and brood mixing (n = 3). Overall, the 28-day chick survival rate was 0.220 (SE = 0.028). We found that mortalities related to the implant procedure and transmitter loss were similar to rates reported by previous researchers who removed chicks from capture sites and implanted transmitters at an alternate location. Subcutaneous implants may be a useful method for attaching transmitters to newly hatched sage-grouse chicks to estimate survival rates, identify causes of mortality, and collect ecological data.     

Survival and site fidelity of Piping Plovers on Long Island, New York

ABSTRACT.   The threatened Atlantic Coast population of Piping Plovers ( Charadrius melodus ) has not increased in recent years and remains 332 pairs short of the recovery goal of 2000 pairs. Habitat loss to development is a major threat to the population, and there has been interest in restoring nesting and foraging habitat. However, the demographic response of coastal Piping Plovers to either habitat loss or creation has not been documented. We estimated survival rates and site fidelity of a declining Piping Plover population on Long Island, New York, from 2001 to 2005 on a beach subject to human development and recreation. The mean annual adult survival was 0.703 ± 0.032 (SE) and was similar among years. Site fidelity during the period of territory establishment averaged 0.827 ± 0.069 (SE). Given this high site fidelity, ensuring the survival of adults is important for maintaining local populations. Although the 2002–2004 average was high, site fidelity was apparently lower in 2003 than in 2002. This decrease in site fidelity may have been related to several years of habitat loss and increasing predation of nests or chicks, as reported in a partly concurrent long-term study at our site. The species-level effect of local dispersal due to anthropogenic habitat loss depends on the fitness of dispersers, and is currently unknown for Piping Plovers.     

Red fox trap success is correlated with piping plover chick survival

Predation management is an important component of managing species of conservation concern. The piping plover (Charadrius melodus; plover), a disturbance-dependent and conservation-reliant shorebird that nests on sandy beaches and barrier islands on the Atlantic Coast, was listed under the United States Endangered Species Act in 1986, with habitat loss and predation stated as key causes of its decline. We evaluated the relationship between a suite of predators and plover chick survival from 2015–2018. We used a camera grid to establish indices of the abundance of 3 known chick predators: red fox (Vulpes vulpes), raccoon (Procyon lotor), and domestic cat. We used camera detections in a survival model to assess potential relationships between predator species detection and plover chick survival. Plover chick survival was negatively related with red fox detection, but not with detection of the other 2 predators. In addition to the correlation with red fox detections, chick survival was negatively related to high plover nesting density. Our results suggest that red foxes were predators of piping plover chicks during our study, likely augmented by other density-dependent sources of mortality. Targeted predator management could aid in conservation of piping plovers in this system as a short-term solution, but long-term recovery plans must also address habitat limitation.     

Effect of Extra-Pair Paternity on Effective Population Size in a Reintroduced Population of the Endangered Hihi, and Potential for Behavioural Management

We collected genetic and behavioural data on hihi (Notiomysts cincta, an endangered New Zealand bird) after reintroduction to Mokoia Island to assess the effect of extrapair copulation on effective population size (N _e), and investigate the potential for increasing N _e through behavioural management. DNA fingerprinting revealed that 46% of chicks (n = 188) resulted from extra-pair paternity, and 82% of broods (n = 56) had at least one extra-pair chick. Of the extra-pair young, 34%(n = 89) were from unpaired males, and the remainder were from paired males. Variance in reproductive success (VRS) among individuals changed between years, and the relative variance among males and females depended on the sex ratio. VRS increased when measured over longer time scales, the variance in recruits being three times higher than the variance in the number of hatchlings. Extra-pair copulation increased VRS by 150% in 1 year and decreased it by 30% in another year, but this only caused a 4% decrease and 8% increase, respectively, to N _e/N. Although there is potential to manage VRS in this species through behavioural management, a more important factor is adult lifespan, which is the main correlate of lifetime reproductive success as well as the determinant of generation time. The high annual mortality rate in Mokoia hihi (females = 64%, males = 52%) has prevented the population from growing, so the key factors limiting N and N _e/N are the same.     

Plasticity of Least Tern and Piping Plover nesting behaviors in response to sand temperature

Birds that nest on the ground in open areas, such as Piping Plovers (Charadrius melodus) and Interior Least Terns (Sternula antillarum athalassos), are exposed to high temperatures in thermally stressful environments. As a result, some ground-nesting avian species have adapted behavioral strategies to maintain thermal regulation of eggs and themselves. We assessed the impact of sand temperature on shorebird nesting behaviors by installing video cameras and thermocouples at 52 Least Tern and 55 Piping Plover nests on the Missouri River in North Dakota during the 2014–2015 breeding seasons. Daily duration and frequency of shading behaviors exhibited a nonlinear relationship with temperature; therefore, we used segmented regressions to determine at what threshold temperature (mean temperature = 25.7^⸰C for shading behavior daily frequency and mean temperature = 25.1^⸰C for shading behavior daily duration) shorebird adults exhibited a behavioral response to rising sand temperatures. Daily nest attendance of both species decreased with increasing sand temperatures in our system. Frequency and duration of daily shading behaviors were positively correlated with sand temperatures above the temperature threshold. Piping Plovers exhibited more and longer shading behaviors above and below the temperature thresholds (below: frequency = 10.30 ± 1.69 se, duration = 7.29 min ± 2.35 se; above: frequency = 59.27 ± 6.87 se) compared to Least Terns (below: frequency = −1.37 ± 1.98 se, duration = −0.73 min ± 1.51 se; above: frequency = 31.32 ± 7.29 se). The effects of sand temperature on avian ground-nesting behavior will be critical to understand in order to adapt or develop recovery plans in response to climate change.     

Transmitter Effects on Growth and Survival of Forster's Tern Chicks

Radio-telemetry is a commonly used scientific technique that allows researchers to collect detailed movement, habitat use, and survival data of animals; however, evidence indicates that using telemetry can affect behavior and survival. Using multiple breeding colonies and years, we investigated the effects of attached radio-transmitters on growth and survival of Forster's tern (Sterna forsteri) chicks in San Francisco Bay, California, USA, 2010–2011. We tested these potential effects at isolated islands that allowed for high re-capture rates (typically >85%) in radio-marked and banded-only chicks. Modeled Gompertz growth curves suggested that transmitters had a small negative effect on some of the asymptotic growth parameters of tern chicks; tarsus (−1.5 ± 0.7% [SE]), culmen (−1.7 ± 1.2%), and wing (−4.9 ± 2.0%) lengths were shorter for radio-marked chicks compared to banded-only chicks. In contrast, there was no difference in asymptotic mass between radio-marked chicks and banded-only chicks. Survival from hatching to fledging was lower for radio-marked chicks than banded-only chicks during 2010 (banded-only = 0.313 ± 0.162 vs. radio-marked = 0.250 ± 0.165) and 2011 (0.193 ± 0.030 vs. 0.123 ± 0.027). Most of the transmitter effect occurred within the first week after hatching, rather than in older chicks. Notably, the effect of transmitters on chick survival was primarily additive, indicating that the effect of transmitters on radio-marked chicks was not influenced by other ecological covariates. Given the effect radio-transmitters had on survival did not change across temporal or ecological gradients, transmitters can still be used to evaluate ecological factors affecting survival and timing of mortality and radio-marked birds can be used to make inferences to the general population. Published 2020. This article is a U.S. Government work and is in the public domain in the USA.     

Effects of water discharge on fledging time,growth, and survival of piping plovers on the Missouri River

River flow management and modification is a global issue, and its effects on river-dependent organisms are pervasive. Flow modification can directly affect avian species through mortality or habitat loss, but less is known about indirect and sublethal effects of flow modification on reproductive output in these species. Young birds are more vulnerable to predation between hatching and fledging than after flight is achieved, but tradeoffs must be made to balance growth and survival. Predation pressure appears to be a significant factor affecting the time to fledging in altricial birds, but less is known about this threat for precocial birds. Birds reaching fledging earlier should have greater rates of survival to migration because their predator escape repertoire includes flight at an earlier age. We evaluated the effect of varying outflows from the Gavins Point Dam on the growth, age at fledging, and survival of piping plover (Charadrius melodus) chicks on the Missouri River (2006–2009). The study was characterized by 2 relatively high flow years (2006 and 2009) and 2 relatively low flow years (2007 and 2008). We used success rate in recapturing chicks in capture–mark–recapture models as an index for fledging. We attempted to recapture all chicks (n = 1,099) by hand every 3–4 days throughout the season to acquire morphological measurements. Models indicated that as flows from the dam increased, age at fledging increased. We also found that increasing flows were associated with decreasing daily survival rates (β_flow = −2.401, 95% CI: −4.351 to −0.452). Flow was also negatively related to chick mass gain, but we found less evidence for an effect on wing-chord length. Increased flows covered wet-substrate foraging habitat, and likely affected plover reproductive output directly through chick survival and indirectly through decreased growth and increased fledging times. © The Wildlife Society, 2013