The Behavioral Ecology and Population Characteristics of Striped Skunks Inhabiting Piper Plover Nesting Beaches on the Island of Martha\u27s Vineyard, Massachusetts

We studied coastal striped skunks (Mephitis mephitis) on the island of Martha’s Vineyard, Massachusetts, USA to gather information on the population characteristics of this mesopredator on Atlantic coast beaches with nesting piping plovers (Charadrius melodus). From 2004 – 2008, we captured and marked 138 skunks and fitted 51 adults with VHF radio-collars. Capture rates ranged from 1 – 7 individuals/100 trap nights (TN) in the spring and 4 – 21 individuals/100 TN in the fall. Spring capture rates were highest at Dogfish Bar (DB), a beach with abundant wrack in the intertidal zone in close proximity to low-density housing, where we estimated a spring density of 8-10 skunks/km2. All adult skunks were residents at this site, and most were initially captured in April/May (100% of males and 67% of females). Spring capture rates were too low for a density estimate at Norton Point/Wasque (NPW), a beach with sparse wrack and farther from development. We initially captured 80% of adult males in April/May but only 1 adult female. Most adult females (88%) were captured in June/July, which coincided with the arrival of anthropogenic food on the beach. While all adult females captured at NPW were residents, 50% of males were non-residents. Half (50%) of all radio-collared skunks died from human-related causes while disease killed another 29%. Female site fidelity was high at both sites, with 40% recurring in subsequent years. While male recurrence at DB was high at 36%, no males recurred at NPW. Similarly, no juveniles recurred in subsequent years at the NPW, but 26% of juveniles recurred at DB. The Martha’s Vineyard skunk population does not exhibit any distinguishing characteristics from mainland striped skunk populations at this time. Skunks captured exhibited all stripe patterns known for the species, but narrow (45%) and short-striped (37%) patterns were most abundant. Adult skunks weighed a mean of 1.47 ± 0.05 kg between April and July and 2.08 ± 0.09 kg between August and November. At beaches where exclusion fencing is not an option for protecting eggs of rare and threatened birds, spring trapping could be effective in reducing skunk densities for most of the nesting season because our data indicates that female territories would remain vacant until late summer. Future research tracking the temporal and spatial variation in wrack line fauna availability on beaches with sparse vs. dense wrack lines will increase our understanding of the factors influencing interactions between piping plovers and predators that share foraging habitat with them, such as skunks and crows. On beaches that are seasonally urban habitats (SUH), research using experimental designs to investigate the influence of predictable anthropogenic food subsidies (PAFS) on the activity and density of generalist predator species during the summer could provide valuable data for management efforts and public outreach aimed at reducing predation on rare and threatened beach species

The Behavioral Ecology and Population Characteristics of Striped Skunks Inhabiting Piper Plover Nesting Beaches on the Island of Martha\u27s Vineyard, Massachusetts

We studied coastal striped skunks (Mephitis mephitis) on the island of Martha’s Vineyard, Massachusetts, USA to gather information on the population characteristics of this mesopredator on Atlantic coast beaches with nesting piping plovers (Charadrius melodus). From 2004 – 2008, we captured and marked 138 skunks and fitted 51 adults with VHF radio-collars. Capture rates ranged from 1 – 7 individuals/100 trap nights (TN) in the spring and 4 – 21 individuals/100 TN in the fall. Spring capture rates were highest at Dogfish Bar (DB), a beach with abundant wrack in the intertidal zone in close proximity to low-density housing, where we estimated a spring density of 8-10 skunks/km2. All adult skunks were residents at this site, and most were initially captured in April/May (100% of males and 67% of females). Spring capture rates were too low for a density estimate at Norton Point/Wasque (NPW), a beach with sparse wrack and farther from development. We initially captured 80% of adult males in April/May but only 1 adult female. Most adult females (88%) were captured in June/July, which coincided with the arrival of anthropogenic food on the beach. While all adult females captured at NPW were residents, 50% of males were non-residents. Half (50%) of all radio-collared skunks died from human-related causes while disease killed another 29%. Female site fidelity was high at both sites, with 40% recurring in subsequent years. While male recurrence at DB was high at 36%, no males recurred at NPW. Similarly, no juveniles recurred in subsequent years at the NPW, but 26% of juveniles recurred at DB. The Martha’s Vineyard skunk population does not exhibit any distinguishing characteristics from mainland striped skunk populations at this time. Skunks captured exhibited all stripe patterns known for the species, but narrow (45%) and short-striped (37%) patterns were most abundant. Adult skunks weighed a mean of 1.47 ± 0.05 kg between April and July and 2.08 ± 0.09 kg between August and November. At beaches where exclusion fencing is not an option for protecting eggs of rare and threatened birds, spring trapping could be effective in reducing skunk densities for most of the nesting season because our data indicates that female territories would remain vacant until late summer. Future research tracking the temporal and spatial variation in wrack line fauna availability on beaches with sparse vs. dense wrack lines will increase our understanding of the factors influencing interactions between piping plovers and predators that share foraging habitat with them, such as skunks and crows. On beaches that are seasonally urban habitats (SUH), research using experimental designs to investigate the influence of predictable anthropogenic food subsidies (PAFS) on the activity and density of generalist predator species during the summer could provide valuable data for management efforts and public outreach aimed at reducing predation on rare and threatened beach species

Genome-wide Trans-ethnic Meta-analysis Identifies Seven Genetic Loci Influencing Erythrocyte Traits and a Role for RBPMS in Erythropoiesis

Genome-wide association studies (GWASs) have identified loci for erythrocyte traits in primarily European ancestry populations. We conducted GWAS meta-analyses of six erythrocyte traits in 71,638 individuals from European, East Asian, and African ancestries using a Bayesian approach to account for heterogeneity in allelic effects and variation in the structure of linkage disequilibrium between ethnicities. We identified seven loci for erythrocyte traits including a locus (RBPMS/GTF2E2) associated with mean corpuscular hemoglobin and mean corpuscular volume. Statistical fine-mapping at this locus pointed to RBPMS at this locus and excluded nearby GTF2E2. Using zebrafish morpholino to evaluate loss of function, we observed a strong in vivo erythropoietic effect for RBPMS but not for GTF2E2, supporting the statistical fine-mapping at this locus and demonstrating that RBPMS is a regulator of erythropoiesis. Our findings show the utility of trans-ethnic GWASs for discovery and characterization of genetic loci influencing hematologic traits

Long-Term Population Monitoring: Lessons Learned From an Endangered Passerine in Hawai‘i

Obtaining reliable population estimates is crucial to monitoring endangered species and developing recovery strategies. The palila (Loxioides bailleui) is an endangered seed-eating Hawaiian honeycreeper restricted to the subalpine forests of Mauna Kea, a volcano on the island of Hawai‘i, USA. The species is vulnerable to extinction primarily because \u3e90% of the population is concentrated in \u3c30 km2 of habitat on the western slope of this high, dormant volcano. Annual surveys of the palila population have been conducted for ecological, legal, and other purposes since 1980. Because refinements to sampling protocols and analytical methods have evolved, we examined means of adapting the monitoring program to produce comparable estimates of abundance over the past 25-year period and into the future. We conducted variable circular plot surveys during the nonbreeding season (Jan– Mar) and this used data to obtain estimates of effective detection radius and annual density with Distance 4.0, Release 2. For comparability over the time-series, we excluded from analysis the data from new transects. We partitioned the 25-year data set (1980–1996 and 1997–2004) into 2 separate analyses because, beginning in 1997, observers received more training to reduce their tendency to estimate distances to 5-m intervals. We used geographic strata in the analysis of recent surveys because changes in habitat may have invalidated the density-based strata used previously. By adding observer and year and observer and time of day as co-variables, we improved the model fit to the 2 data sets, respectively. Annual estimates were confounded by changes in sampling methodology and analytical procedures over time. However, the addition of new transects, increased training for observers, and use of exact distance estimates instead of rounding also improved model fit. Habitat characteristics and behavior of palila that potentially influenced detection probability, sampling, analysis, and interpretation were regeneration of trees in response to reduced numbers of introduced browsing mammals, seasonally variable rates of vocalization, non-territoriality, and resource-tracking along an elevation gradient. We believe our adaptive approach to analysis and interpretation of 25 years of annual variable circular plot data could help guide similar long-term monitoring efforts

Survival and Physiologic Response of Common Amakihi and Japanese White-Eyes During Simulated Translocation

We evaluated the effects of three translocation trials on Common Amakihi (Hemignathus virens) and Japanese White-eyes (Zosterops japonicus). Trial 1 involved capturing birds, transporting them on rough roads for 4 hr followed by holding in an aviary for 48 hr without overnight thermal support prior to release. Trial 2 involved capture, then holding in an aviary for 48 hr with overnight thermal support followed by transport for 4 hr prior to release. Trial 3 and 1 were identical except that overnight thermal support was provided during trial 3. We monitored survival, food consumption, weight change, and fecal production during captivity as well as changes in hematocrit, estimated total solids, heterophil to lymphocyte ratios, plasma uric acid, and creatinine phosphokinase (CPK) at capture and release. Survival was significantly lower for Amakihi during trial 1 (no thermal support). Birds that died lost significantly more weight than those that survived. Regardless of trial, birds responded to translocation by a combination of weight loss, anemia, hypoproteninemia, and elevated heterophil to lymphocyte ratio, uric acid, and CPK levels. The first 24 hr of captivity posed the greatest risk to birds regardless of whether transport or holding occurred first. Food consumption, fecal production, and weight all decreased at night, and overnight thermal support during holding was critical if ambient temperatures dipped to freezing. We recommend that if small passerines are to be held for \u3e 12 hr, they be monitored individually for weight loss, food consumption, and fecal production

Consequences of Antenna Design in Telemetry Studies of Small Passerines

Entanglement and mortality of Palila (Loxioides bailleui), an endangered Hawaiian honeycreeper, occurred when birds were radio-tagged with transmitters equipped with a long, limp, solder-tipped antenna. Birds were found suspended in trees by their transmitter antenna on eight occasions. Although these birds eventually freed themselves or were freed by us, at least one bird died afterwards. For radio telemetry studies of small passerine species we recommend avoiding transmitters equipped with an antenna that is bulbous at the tip, \u3e16 cm in length, limp, and shiny

Availability of food resources, distribution of invasive species, and conservation of a Hawaiian bird along a gradient of elevation

Aim We evaluated how an elevation gradient affects: (1) the availability of food required by a specialist seed-eater, Loxioides bailleui Oustalet (Drepanidinae), or palila, and hence the distribution of this endangered Hawaiian bird, and (2) the distribution of alien threats to Loxioides populations, their primary foods, and their dry-forest habitat, and hence strategies for their conservation. Location We worked throughout the subalpine forest that encircles Mauna Kea Volcano, Hawai‘i Island, but we focused our studies mainly on the western slope between 2000 and 3000 m elevation, where the gradient of elevation was greatest and palila were most abundant. Methods We determined phenology and productivity patterns of the endemic dry-forest tree species, Sophora chrysophylla (Salisb.) Seem. (Fabaceae), or māmane, which provides Loxioides with most of their food, and another common endemic tree, Myoporum sandwicense A. Gray (Myoporaceae), or naio, which provides some resources, along a 786-m elevation gradient at monthly intervals for 10 years (Sophora only). We also determined the availability each month of moth larvae (Lepidoptera) for that were important in the diet of nestling and adult palila. In addition, we documented the incidence of parasitism on moth larvae by several wasp (Hymenoptera) and fly (Diptera) species, and we determined the distribution of predatory wasps and ants (Hymenoptera), which potentially threaten insect prey of birds. Percentage cover of alien grass species that pose fire threats in palila habitat and other weeds were assessed during one survey. Small mammal abundance and distribution were determined by trapping during three (rodent) or five (carnivore) surveys. Results Sophora flower and seed (pod) availability varied predictably along the elevation gradient, with about 4 months separating peaks in reproduction at high and low elevations. This, together with highly variable production of flowers and pods within elevation strata, resulted in Sophora resources being available to Loxioides throughout the year on the western slope of Mauna Kea. Sophora produced flowers and pods more seasonally where gradients of elevation were short; thus, resources were available less consistently. In contrast, Myoporum produced flowers and fruits with little variation with respect to season or elevation. The availability of important insect prey of Loxioides was also related to elevation, in part because threats to Lepidoptera larvae from parasitic wasps were generally less at higher elevations. Threats to insect prey from predatory ants was also less at higher elevations but the abundance of predatory wasps was not related to elevation. Several weeds that pose the most serious threats to Loxioides habitat were more abundant at mid and low elevations, and alien grass cover was somewhat greater at mid elevation, thereby increasing fire risks in the centre of Loxioides habitat. Predatory mammals, in particular Felis catus Linnaeus, were common throughout the subalpine forest of Mauna Kea. However, Rattus rattus Linnaeus was rare, especially at higher elevations, whereas Mus musculus Linnaeus was more abundant at lower elevations. Main conclusions Loxioides are concentrated in habitat that is distributed along a substantial gradient of elevation at least in part because food is available throughout the year and threats to food resources are less concentrated. To recover Loxioides elsewhere in its former range, habitats must be restored and alien threats reduced along extensive elevation gradients. Conservation along environmental gradients will likely benefit other Hawaiian birds that track the availability of food across landscapes or that have been stranded in the higher portions of their original ranges because of the greater impacts of alien diseases, predators, food competitors, and habitat stressors at lower elevations