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At least 1,045 records · Page 58Linked to original sources
USGS2008

Hepatic minerals of white-tailed and mule deer in the southern Black Hills, South Dakota

Because there is a paucity of information on the mineral requirements of free-ranging deer, data are needed from clinically healthy deer to provide a basis for the diagnosis of mineral deficiencies. To our knowledge, no reports are available on baseline hepatic mineral concentrations from sympatric white-tailed deer (Odocoileus virginianus) and mule deer (Odocoileus hemionus) using different habitats in the Northern Great Plains. We assessed variation in hepatic minerals of female white-tailed deer (n=42) and mule deer (n=41). Deer were collected in February and August 2002 and 2003 from study areas in Custer and Pennington Counties, South Dakota, in and adjacent to a wildfire burn. Hepatic samples were tested for levels (parts per million; ppm) of aluminum (Al), antimony (Sb), arsenic (As), barium (Ba), boron (B), cadmium (Cd), calcium (Ca), chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), lead (Pb), magnesium (Mg), manganese (Mn), mercury (Hg), molybdenum (Mo), nickel (Ni), phosphorus (P), potassium (K), selenium (Se), sodium (Na), sulfur (S), thalium (T1), and zinc (Zn). We predicted that variability in element concentrations would occur between burned and unburned habitat due to changes in plant communities and thereby forage availability. We determined that Zn, Cu, and Ba values differed (P???0.05) between habitats. Because of the nutritional demands of gestation and lactation, we hypothesized that elemental concentrations would vary depending on reproductive status; Cd, Cu, Ca, P, Mn, Mo, Na, and Zn values differed (P???0.05) by reproductive status. We also hypothesized that, due to variation in feeding strategies and morphology between deer species, hepatic elemental concentrations would reflect dietary differences; Ca, Cu, K, Co, Mo, Se, and Zn differed (P???0.05) between species. Further research is needed to determine causes of variation in hepatic mineral levels due to habitat, reproductive status, and species. ?? Wildlife Disease Association 2008.

Journal of Wildlife Diseases↗
USGS2010

Unifying quantitative life-history theory and field endocrinology to assess prudent parenthood in a long-lived seabird

Question: Can field measurements of stress hormones help us to assess the prudent parent hypothesis in a long-lived seabird? Organism: Black-legged kittiwake, Rissa tridactyla . Location: Duck and Gull Islands, Cook Inlet, Alaska, USA. Methods: We examined the statistical relationship between the stress hormone corticosterone and mortality in black-legged kittiwakes. We built a demographic model of the kittiwake life cycle to determine whether the mortality rates associated with persisting in a breeding attempt despite high corticosterone caused the birds to sacrifice more lifetime reproductive output than they gain from one year’s breeding. Results: The probability of apparent mortality increased with corticosterone, suggesting some birds incurred increased mortality risk for the sake of breeding. For Duck Island (low reproductive success), it appears birds sacrificed more lifetime reproductive success than a prudent parent would. On Gull Island, it appears most but possibly not all birds were behaving in ways consistent with theory, although definitive statements require larger samples of highly stressed birds.

Alaska↗
USGS2012

Status and limiting factors of two rare plant species in dry montane communities of Hawai`i Volcanoes National Park.

Two rare plants native to montane dry forests and woodland communities of Hawai`i Volcanoes National Park (HAVO) were studied for more than two years to determine their stand structure, short-term mortality rates, patterns of reproductive phenology, success of fruit production, floral visitor composition, seed germination rates in the greenhouse, and survival of both natural and planted seedlings. Phyllostegia stachyoides , a shrubby Hawaiian mint (Lamiaceae) that is a species of concern, was studied within two small kīpuka at a natural population on the park’s Mauna Loa Strip, and three plantings at sites along the Mauna Loa Road were also monitored. Silene hawaiiensis , a threatened shrub species in the pink family (Caryophyllaceae), was monitored at two natural populations, one on Mauna Loa at the Three Trees Kīpuka and the second on Kīlauea Crater Rim south of Halema`uma`u. Silene hawaiiensis plantings were also made inside and outside ungulate exclosures at the park’s Kahuku Unit Phyllostegia stachyoides appeared to have a relatively stable natural population in HAVO with approximately 19% adult plant mortality over three years and recruitment of natural seedlings. Despite high mortality (~98%), some seedlings persisted for more than a year, and recruitment of new plants into the population exceeded the losses of adult plants. Flowering and fruiting phenology was annual and seasonal with peak appearance of buds and flowers in spring and greatest abundance of mature fruit in the summer and fall. Successful production of green fruit from buds and flowers was very high (45%), and green fruit transitioned to mature fruit at a rate of 17.8%. Five insect species were observed visiting flowers, and those with the greatest visitation rates were the alien hover fly Allograpta obliqua (Syrphidae) and the endemic yellowfaced bee Hylaeus difficilis (Colletidae). Both insect species were shown to be carrying pollen of P. stachyoides . Seed germination rates in the greenhouse were variable but ranged as high as 80.4%. Mortality of seedlings planted at three sites along the Mauna Loa Road was very high (~90%) within 2–3 years of planting. There was no significant difference in the mortality or growth of seedlings planted in areas with little grass compared to those in adjacent areas with high grass cover. Silene hawaiiensis had a stable population structure at the Mauna Loa study area, but its population structure at the Kīlauea study site was flat to declining. Mortality of adult plants was low on Mauna Loa (6.5%), but was greater than 30% at the Kīlauea Crater Rim site. Among regularly monitored plants at the Kīlauea site, losses were observed in all size classes between 2006 and 2008. Natural seedling recruitment was observed in stand structure plots at both sites between 2006 and 2007, but numbers of seedlings were low and did not compensate for losses of adult plants. Reproductive phenology was annual with buds and flowers observed in summer and fall, and fruit formed in the fall and winter. The production of immature fruit capsules from buds and flowers was high (51.2%) and tagged immature fruit became mature fruit at a high rate of 66.7%. Floral visitation rates were very low in timed observations and only three insect species were identified visiting S. hawaiiensis flowers: native yellow-faced bees Hylaeus difficilis and H. volcanicus , and the alien hover fly Allograpta exotica . A seed dispersal experiment at the Kīlauea Crater Rim site demonstrated that wind dispersed seeds could travel at least 40 m from S. hawaiiensis plants with mature open capsules. Seed germination rates varied from 7.0 to 73.0% in greenhouse trials. Mortality of planted seedlings at Kahuku was not significantly greater outside ungulate exclosures than inside, but growth in height and production of reproductive structures was significantly greater in protected areas inside exclosures. In the current study, the seedling stage was the most vulnerable part of the life cycle for both P . stachyoides and S. hawaiiensis , and low seedling recruitment appeared to be the most important limiting factor for these species

Hawaii↗
USGS2014

Waterfowl habitat use and selection during the remigial moult period in the northern hemisphere

This paper reviews factors affecting site selection amongst waterfowl (Anatidae) during the flightless remigial moult, emphasising the roles of predation and food supply (especially protein and energy). The current literature suggests survival during flightless moult is at least as high as at other times of the annual cycle, but documented cases of predation of flightless waterfowl under particular conditions lead us to infer that habitat selection is generally highly effective in mitigating or avoiding predation. High energetic costs of feather replacement and specific amino-acid requirements for their construction imply adoption of special energetic and nutritional strategies at a time when flightlessness limits movements. Some waterfowl meet their energy needs from endogenous stores accumulated prior to remigial moult, others rely on exogenous supply, but this varies with species, age, reproductive status and site. Limited evidence suggests feather proteins are derived from endogenous and exogenous sources which may affect site selection. Remigial moult does not occur independently of other annual cycle events and is affected by reproductive investment and success. Hence, moult strategies are affected by age, sex and reproductive history, and may be influenced by the need to attain a certain internal state for the next stage in the annual cycle (e.g. autumn migration). We know little about habitat selection during moult and urge more research of this poorly known part of the annual cycle, with particular emphasis on identifying key concentrations and habitats for specific flyway populations and the effects of disturbance upon these. This knowledge will better inform conservation actions and management actions concerning waterfowl during moult and the habitats that they exploit.

Wildfowl↗
USGS2015

Adaptive harvest management for the Svalbard population of Pink-Footed Geese: 2014 progress summary

This document describes progress to date on the development of an adaptive harvest-management strategy for maintaining the Svalbard population of pink-footed geese (Anser brachyrhynchus) near their agreed target level (60 thousand) by providing for sustainable harvests in Norway and Denmark. Specifically, this report provides an assessment of the most recent monitoring information and its implications for the harvest management strategy. The development of a passively adaptive harvest management strategy requires specification of four elements: (a) a set of alternative population models, describing the effects of harvest and other relevant environmental factors; (b) a set of probabilities describing the relative credibility of the alternative models, which are updated each year based on a comparison of model predictions and monitoring information; (c) a set of alternative harvest quotas, from which a 3-year quota is chosen; and (d) an objective function, by which alternative harvest strategies can be evaluated and an optimal strategy chosen. By combining varying hypotheses about survival and reproduction, a suite of nine models have been developed that represent a wide range of possibilities concerning the extent to which demographic rates are density dependent or independent, and the extent to which spring temperatures are important. Five of the models incorporate density-dependent mechanisms that would maintain the population near a carrying capacity (i.e., in the absence of harvest) of 65k – 129k depending on the specific model. The remaining four models are density independent and predict an exponentially growing population even with moderate levels of harvest. The most current set of monitoring information was used to update model weights for the period 1991 – 2013. Current model weights suggest little or no evidence for density-dependent survival and reproduction. These results suggest that the pink-footed goose population may have recently experienced a release from density-dependent mechanisms, corresponding to the period of most rapid growth in population size. There was equivocal evidence for the effect of May temperature days (number of days with temperatures above freezing: TempDays) on survival and on reproduction. During the summer of 2013 we computed an optimal harvest strategy for the 3-year period 2013 – 2015. The strategy suggested that the appropriate annual harvest quota is 15 thousand. The 1-year harvest strategy calculated to determine whether an emergency closure of the hunting season is required this year suggested an allowable harvest of 25.0 thousand; thus, a hunting-season closure is not warranted. If the harvest quota of 15 thousand were met in the coming hunting season, the next population count would be expected to be 71.0 thousand. If only the most recent 4-year mean harvest were realized (11.3 thousand), a population size of 74.8 thousand would be expected. Simulations suggest that it will take approximately seven years at current harvest levels to reduce population size to the goal of 60 thousand. However, it is possible that the extension of the forthcoming hunting season in Denmark could result in a total harvest approaching 15 thousand; in this case, simulations suggest it would only take about three years to reach the goal.

Svalbard↗
USGS2015

Wetland occupancy of pond-breeding amphibians in Yosemite National Park, USA

We estimated wetland occupancy and population trends for three species of pond-breeding anurans in Yosemite National Park from 2007-2011. We used a double survey technique in which two observers independently surveyed each site on the same day. Double surveys allowed us to calculate detectability for the three most common anurans within the park: Rana sierrae, Anaxyrus canorus, and Pseudacris regilla. Annual estimates of detectability were generally high; mean detectability ranged from 73.7% + 0.6 (SE) for any life history stage of A. canorus to 86.7% + 0.7 for sites with P. regilla reproduction (eggs or larvae present). Detectability was most variable for Anaxyrus canorus, which ranged from 45.9% to 99.7%. The probability of occupancy for R. sierrae was highest in larger, low-elevation wetlands that lacked fish. Anaxyrus canorus were more common in shallow high-elevation ponds; their occurrence was minimally impacted by the presence of fish. Finally, occurrence of P. regilla was largely unrelated to wetland size and elevation, but like R. sierrae, they were less likely to occupy sites with fi sh. Occupancy showed no trend over the five years of our study for R. sierrae or A. canorus when considering either sites with any life stage or only sites with reproduction. However, P. regilla showed a modest downward trend for sites with any life stage and sites with reproduction. Our results for R. sierrae run counter to expectations given recent concern about the decline of this species, while our findings for P. regilla raise concerns for this widespread and generally common species.

California↗
USGS2010

Limiting factors of four rare plant species in `Ōla`A Forest of Hawai'i Volcanoes National Park

Three endangered or candidate endangered plant species native to `Ōla`a Forest ( Cyrtandra giffardii , ha`iwale; Phyllostegia floribunda , a mint with no common name; and Sicyos alba , `ānunu) were studied for more than 2 years to determine their stand structures, short-term mortality rates, patterns of reproductive phenology, success of fruit production, seed germination rates in the greenhouse, presence of soil seed bank, and survival of both natural and planted seedlings. The role of rodents as seed predators was evaluated for S. alba using seed offerings in open and closed stations. A 4th endangered species at a remote site in `Ōla`a ( Cyrtandra tintinnabula ) was visited to determine its stand structure and mortality rate. Cyrtandra giffardii displayed a stable population structure with many adults and few small or very large plants; the monitored population had a mortality rate of 7.3% over 3 years. Mortality of plantings from 2003-2004 in a re-introduced population of Phyllostegia floribunda was 21.4%. The stand structure of C. tintinnabula indicated a relatively stable population with both small and large plants present and a short-term mortality rate between visits of 14.5- 17.0%. Four groups of S. alba vines were monitored; 3 of these have persisted in place for at least 15 years. All species monitored had annual patterns of flower and fruit phenology, although male inflorescences of S. alba showed a subannual pattern. Successful transition of flowers to fruit was high for P. floribunda (51.5%), moderate for C. giffardii (23.3%) and undetermined for S. alba . High percentage viability was demonstrated for seeds of P. floribunda and S. alba (78.5-100% positive to strongly positive in tetrazolium tests), but seed viability was not tested for C. giffardii . Greenhouse germination rates were high for P. floribunda (88.0-92.0%), but variable and relatively low for C. giffardii (0-19.3%) and S. alba (4.0-11.1% in 2007 and 0 in 2008). No soil seed bank was detected for S. alba in 3 seasonal samplings, but P. floribunda was found to have a viable seed bank in April that persisted from at least the previous summer. Rodent predation of S. alba seeds was 93.3% in fruit offerings in accessible bait stations. Mortality of natural seedlings was high for both P. floribunda (90.2%) and S. alba (69.7%). Planted seedlings of P. floribunda produced flowers and fruit in their first year, and reproduction was higher in sunny plots than in shady plots. Mortality was high in both planting treatments, and survival rates did not differ significantly in sun and shade (χ 2 =0.48, df = 1, p = 0.490). Three planted seedlings of S. alba survived for 12-16 months but did not reproduce. Floral visitors were observed at C. giffardii and P. floribunda using digital video cameras and recorders. In almost 200 hours of observation, no visitors entered the flowers of C. giffardii , although 1 very small insect, either a micro-wasp (Hymenoptera) or fly (Diptera) was seen on the exterior of a corolla. In almost 300 hours of video observation, 3 floral visitors were identified at P. floribunda flowers. Honeybees ( Apis mellifera ) were likely pollinators, as they contacted both anthers and stigma of flowers. The mean visitation rate of honeybees was 0.003 visit/flower/hour, and visit duration ranged from 2 to 17 seconds. Fruit flies (Drosophilidae of undetermined species) crawled around flower interiors, but did not seem to forage for either nectar or pollen. Fruit fly mean visitation rate was 0.006 visit/flower/hour, and visit duration was 28 to 1,424 seconds. The 3rd observed insect visitor was an endemic geometrid moth caterpillar ( Lophoplusia giffardi ), which was seen feeding on foliage and flowers of P. floribunda . In conclusion, 2 of the 3 regularly-monitored rare plant species of `Ōla`a Forest appeared to have more than 1 limiting factor inhibiting the natural increase in their populations, while for P. floribunda the most important factor was high seedling mortality. Most plants of the monitored C. giffardii population appeared to be hybrids, probably with the more common species C. lysiosepala . Seed germination rates were low, and natural seedlings were not observed. Pollinators were not seen in many hours of observation, indicating that cross pollination is a rare or uncommon event. The re-introduced population of P. floribunda had relatively low mortality, and reproduction was successful with high rates of fruit formation from abundant flowers. Seed germination rates were high, and a soil seed bank was detected. Natural seedling recruitment was observed, but high seedling mortality indicated that this life stage was the most vulnerable in the species. The population of S. alba was small and the vine life form precluded an accurate estimate of the number of adult plants in `Ōla`a Forest. Natural dormancy was likely a factor in the observed low rate of seed germination. No soil seed bank was detected, and alien rodents were implicated as seed predators. Natural recruitment was observed at multiple sites in `Ōla`a, but seedling mortality was high. The cause of seedling mortality was not identified.

Hawaii↗
USGS1988

Effects of the 1982-83 El Niño – Southern Oscillation on Pacific Ocean bird populations

Seabird reproductive success, population size, and movements in the Pacific region responded dramatically to the 1982-83 El Niño – Southern Oscillation (ENSO). At sites within the North and South Pacific Gyres, the onset of seabird responses tracked oceanographic changes related to ENSO; to the north of the gyres, responses were delayed 1 yr. Reproductive failures and high adult mortality were detected at all sites investigated. Post-ENSO, the return to “normal” nesting patterns depended on species and locality. The 1982-83 ENSO revealed a dimension to the variability in seabird reproductive biology only now appreciated by ornithologists.

Conference Paper↗
USGS2018

Adaptive harvest management for the Svalbard population of pink-footed geese: 2018 progress summary

This report describes progress on development and implementation of an adaptive harvest management program for maintaining the Svalbard population of Pink-footed Geese (Anser brachyrhynchus) near their target level (60,000) by providing sustainable harvests in Norway and Denmark. Specifically, this report provides an assessment of recent monitoring information and its implications for hunting seasons in 2018. An Adaptive Harvest Management (AHM) program requires specification of four elements: (a) A set of alternative population models, which bound the uncertainty about population dynamics; (b) A set of weights describing the relative credibility of the alternative models, which are updated each year based on a comparison of model predictions and monitoring information; (c) A set of alternative harvest quotas from which to choose; and (d) An objective function, by which alternative harvest strategies are evaluated and an optimal strategy chosen. The most current set of monitoring information was used to update model weights for the 1991-2017 period. Current model weights suggest little evidence for density-dependent survival and reproduction. These results suggest that the Pink-footed Goose population may have experienced a release from density-dependent mechanisms, corresponding to the period of rapid growth in population size. There is equivocal evidence for the effect of the number of days above freezing in May in Svalbard on survival, but the evidence for an effect on reproduction has been increasing in recent years. Since the 2016 hunting season, harvest quotas are prescribed on an annual basis rather than every three years because of the potential to better meet management objectives. Based on updated model probabilities, the November 2017 population size (72,000), the proportion of the population comprised of one-year-old birds (0.076), and days above freezing in Svalbard in May 2018 (27), the optimal harvest quota for the 2018 hunting season is approximately 27,000. With the agreed upon harvest allocation of 30% Norway and 70% Denmark, the national quotas are 8,100 and 18,900, respectively, which are higher than the harvests realized in previous years. In 2017 the quota for the two countries combined was 36,000, but only a harvest of about 11,400 was realized. The decrease in harvest quota for 2018 is largely attributable to the apparent decline in population size. We also describe the ongoing development of an Integrated Population Model (IPM), which uses all available demographic data for Pink-footed Geese in a single, unified analysis. IPM estimates of harvest rates of adult geese were variable and relatively low prior to the implementation of AHM (2013), and have been relatively high since. The increase in harvest rates has been accompanied by a decline in annual survival. The ratio of young-of-the-year to older birds just prior to the hunting season has been variable over time, and since about 2005 has been highly correlated with the number of days above freezing in May in Svalbard. IPM estimates of population size suggest that abundance of Pink-footed Geese has been relatively stable, or declining slightly, in recent years. Based on the IPM estimate of population size in November 2017 of 68,800 (95% credible interval: 58,200 – 79,400), the optimal harvest quota for the 2018 hunting season is 15,000. This is lower than that derived from the set of nine discrete models because the IPM estimate of November population size is lower than the November count, and because the IPM model does not consider May temperatures in Svalbard, but rather assumes reproductive success varies randomly about the mean.

Report↗
USGS2018

Effects of rearing environment on behavior of captive-reared whooping cranes

Whooping cranes ( Grus americana ) are 1 of the most endangered bird species in North America. In 1999 the Whooping Crane Eastern Partnership was formed to establish a migratory population of whooping cranes in eastern North America. These efforts have been extremely successful in terms of adult survival but reproductive success post-release has been low. One hypothesis developed to explain such low reproductive success is that captive-rearing techniques fail to prepare the birds to be effective parents. Captive-reared whooping cranes at the U.S. Geological Survey, Patuxent Wildlife Research Center, Laurel, Maryland, are either reared by humans in crane costumes or by surrogate conspecific adults. We hypothesized that the 2 captive-rearing techniques differentially shaped chick behavior. To test this, we measured chick behavior daily as well as when chicks were placed in novel environments. Twice per day, every day, 5-minute focal observations were conducted on each chick. When they were introduced to a novel environment, 10-minute focal observations were conducted within 1 hour of introduction. The 2 groups differed significantly: costume-reared chicks were, on average, more stationary than parent-reared birds. These data suggest that future research should be done to determine whether or not rearing technique could have longterm effects on post-release behavior and reproductive success

Conference Paper↗
USGS1992

Ecology of band-tailed pigeons in Oregon

The ecology of band-tailed pigeons ( Columba fasciata ) was investigated in western Oregon to assess the roles of survival and recruitment to population status and the relation of food, minerals, and diet to reproduction strategy. Band-tailed pigeons congregated at mineral deposits to consume minerals from mid-June to mid-September. Males generally arrived and departed between daylight and 1000 h and females between 0930 and 1200 h, the inverse of the nest attentive schedules for the sexes. The pigeons used one or several adjacent mineral sites throughout the summer and most returned to the same mineral site in subsequent years. Band-tailed pigeons were resident from April through September; migration apparently did not begin before late September. Three indirect sources of evidence indicated that fledging began in June, reached a peak in mid- August, and continued until late September. Second year (SY) band-tailed pigeons apparently began nesting later than and were about one-third as productive as adults. In Oregon, most of the adult population could fledge as many as two young over the 100-110-day nesting period, resulting in a maximum potential recruitment of 47-50% juveniles. We estimated that the fall population contained about 23% juveniles, 12% yearlings, and 65% adults. Mean annual survival of adults was 63.7%, but was year-specific. To maintain a stable population with the estimated survival rates required production near the biotic potential (40.8%). Conversely, a stable population could be attained with the estimated rate of recruitment (23%) and high but realistic rates of survival (adults, 83%; juveniles, 68%). Counts of band-tailed pigeons at mineral sites in Oregon indicated that the population had undergone two periods of modest increase (2.4-7.1% per year) and two periods of sharp decline (10.4-11.1% per year). In 1988 the population index was only 34% of the 1950-88 average. Harvest of band-tailed pigeons in the three Pacific Coast states averaged 414,000 from 1957 to 1983; about 55% of the harvest took place in California, 23% in Washington, and 22% in Oregon. In Oregon, about 65% of the harvest took place in the first 10 days of September and 40% was at mineral sites. Fewer juveniles were shot at mineral sites (13%) than at feeding areas (25%). Hunting at mineral sites was directed at experienced breeders and may be particularly detrimental to the population. However, the overall effect of hunting on abundance was not determined. Band-tailed pigeons fed extensively on elder ( Sambucus spp.) and cascara buckthorn ( Rhamnus purshiana ) berries while nesting. The emergence of Pacific red elder (S. callicarpa) berries in June provided the food resources necessary for initiation of reproduction in Oregon, and probably throughout the Northwest. Elder berries contain little calcium (0.06-0.12%), therefore, the pigeons in the Northwest may require a mineral supplement in their diet. Mineral sites may be the scarcest resource required for reproduction by band-tailed pigeons in the Northwest.

Oregon↗
USGS2020

Seabird synthesis

Overall, the status of seabirds was fair to good in the WGOA in 2020, with limited data available from Middleton Island, Cook Inlet, and the Kodiak Archipelago (Figure 63). Colony attendance remains low in some populations compared to historic levels, and some colonies were newly abandoned. However, when birds did arrive to breed, reproductive success generally appeared fair to good for fish-eating, surface-feeding birds and fish-eating, diving birds. There was spatial variability in colony attendance and reproductive success, with Middleton Island birds performing more strongly than Kodiak Island or Cook Inlet. Middleton Island populations from both these groups experienced their strongest breeding seasons since the marine heatwave began in 2014, suggesting an increase in the availability of small schooling fish in that region of WGOA. No large-scale mortality event was recorded based on monthly beach surveys in the WGOA. This year’s integrated approach to reporting seabird status is less comparable to previous Ecosystem Status Reports, as the Alaska Maritime National Wildlife Refuge’s seabird reproductive success time series were not updated, due to COVID-19 related survey cancellations.

Alaska↗
USGS2023

Parental infanticide by egg destruction in Red-billed Tropicbirds Phaethon aethereus on the Caribbean island of Sint Eustatius

Avian reproduction is a process that requires extensive energetic input by parents, particularly in pelagic seabirds. Parental infanticide has rarely been reported in pelagic seabirds, and its frequency among taxa is therefore difficult to determine. Using data from remote cameras, two cases of probable parental infanticide in Red-billed Tropicbirds Phaethon aethereus were captured on Sint Eustatius in the 2021–2022 breeding season. Both cases are presented with images collected from remote cameras as evidence. While appearing counterproductive, parental infanticide may provide an alternative reproduction strategy that favors lifetime reproductive success over short term success.

Article↗
USGS2023

Evaluating the spatial and temporal distribution and ecology of Bighead and Silver Carp and native fishes of the lower Red River basin

We investigated the spatial and temporal distribution of Bighead Carp and Silver Carp (hereafter Carp) in the lower Red River basin of Arkansas. Our study objectives were: 1) determine the spatial and temporal extent of Bighead and Silver Carp in the Red River basin of Arkansas; 2) determine habitat associations of large river fish assemblages; and 3) summarize the demographics of Bighead and Silver Carp. We sampled 67 reaches in the lower Red River and its major tributaries for juvenile Carp and other small-bodied fishes (24 of the reaches were in the Arkansas portion of the Red River). We conducted repeated surveys in these reaches where the reaches were sampled 2-3 times over approximately 2 years representing 242 surveys (95 surveys in Arkansas). We completed adult Carp and native fish assemblage sampling across 61 reaches (22 reaches in Arkansas) where we also repeated surveys at these locations (245 total surveys, 100 surveys completed in Arkansas during the reporting period). We captured the most large-bodied fishes (including Carp) using gillnets and electrofishing, whereas fyke nets and seine hauls collected mainly smaller-bodied fishes. Hoop nets captured fewer fishes when compared to other gear types. We sampled 120,072 fishes, comprising 70 species and 41 genera, from the mainstem Red River in Arkansas. We used data associated with the entire catchment (including OK and TX data) to model the occupancy of adult fishes including both carp species. Carp tended to occupy reaches with the presence of slackwater habitat, that were deeper and narrower (lower habitat complexity), with higher discharge conditions, and were positively associated with chlorophyll-a concentrations. Adult and juvenile assemblage structure varied with reach scale attributes with notable differences among some taxonomically similar species. No carp under the age of 3 were sampled in the catchment. Bighead Carp and Silver Carp in the Red River catchment appear to live longer and grow larger than other populations. Silver Carp and Bighead Carp in the lower Red River had a theoretical maximum length (L_∞) of 920 and 1348-mm TL, respectively. The oldest sampled Silver Carp and Bighead Carp were age 14 and 17, respectively. Bighead Carp growth was positively associated with warmer air temperatures and negatively associated with discharge variability. Similarly, Silver Carp growth was positively associated with the warm air temperature and negatively associated with discharge variability. However, Silver Carp growth was also positively related to high discharge conditions and the variability of air temperature. Silver Carp annual mortality was relatively low and recruitment into the population appeared steady. It appears that Carp are likely coming from another catchment, have only limited or periodic successful reproduction in the study area, or spawn downriver in LA. Continued monitoring for reproductive success would be helpful. Moreover, if the goal is to greatly reduce or eliminate carp, then strategies to prevent further immigration would be ideal before reproduction occurs or becomes more successful. Targeted removal may then be useful for reducing numbers already in the catchment; however, there are also oxbow lakes that contain carp but appear only connected to the river during major floods (i.e., possible source locations).

Cooperator Science Series↗
USGS2024

An analytical approach for simulating effects of avalanches on mountain goat population dynamics: Implications for management and conservation

Mountain environments with snow avalanche hazard cover about 6% of Earth’s land area and occur on all continents. Whereas human risks associated with avalanche hazard have been widely studied, little is known about how avalanche activity affects population dynamics in mountain wildlife. Globally, 32 species of mountain ungulates across 70 countries occupy avalanche-prone terrain. Avalanches comprise the leading cause of mortality in coastal Alaskan mountain goats (mean = 36%, range = 23 - 65%, depending on area), and disproportionately remove prime-aged individuals from populations. The implications of such rates and patterns of mortality on population growth rate are likely to be significant given the species’ low reproductive productivity, but further clarity is needed. To fill this knowledge gap, we developed a sex- and age-specific population modeling approach that integrates both reproduction and mortality to simulate the effects of avalanche-caused mortality on population growth rate across a range of empirically-observed states of avalanche-caused mortality (minimum, mean, maximum). Simulations were conducted to illustrate model functionality, and also provide insight about potential avalanche impacts on population demographic processes. For example, when severe avalanche years occur populations can experience significant additive mortality and declines (up to 15%). Due to low reproductive rates and slow life-history strategy of the species, such impacts can lead to long demographic recovery times (up to 11 years). From a species conservation perspective, such impacts are striking, and highlight the utility of employing a quantitative modeling approach to predict possible effects of avalanches on mountain ungulate population dynamics and viability. Our work explicitly builds upon recent findings about the importance of avalanches on mountain-adapted animal populations, and associated implications for the cultural and ecological communities that depend on them.

Alaska↗
USGS2021

Climate change implications for the conservation of amphibians in tropical environments.

The U.S. Fish and Wildlife Service and the Puerto Rico Department of Natural and Environmental Resources want to develop a plan of actions to protect 12 species of coqui frogs (Eleutherodactylus spp.) that are currently considered at risk of being considered threatened or endangered, requiring additional protections under the Endangered Species Act. Actions center on two possible adaptation strategies: a) translocations to suitable, unoccupied habitat, and b) identifying climate-resilient habitats to ensure the persistence of species. Knowledge required to implement these strategies includes understanding how microhabitat and microclimatic factors – the local environmental conditions around individual frogs influence their occupancy (distribution), abundance, and reproduction; these were estimated by focusing on four representative species (E. wightmanae, E. brittoni, E. antillensis, and E. coqui). The abundance of all species but E. antillensis was positively and strongly influenced by moisture levels. As expected, E. antillensis exhibited an opposite relationship. Similarly, the reproductive activity of E. coqui was influenced by higher relative humidity and the presence of a chorus of other individuals. We found that our four focal species were not affected (e.g., abundance, reproduction) by the passing of hurricane Maria in September 2017, possibly because fallen debris creates conditions of increased food and shelter. Our findings help to assess habitat suitability, potential climate refuges, and inform timing for managed translocations.

Final Report↗
USGS2003

A review of lake trout (Salvelinus namaycush) restoration in Lake Ontario from an early life history perspective

The authors conclude that small numbers of lake trout spawned successfully each year during 1992-97 in Lake Ontario, although this has yet to result in a trend of increasing natural reproduction. Juxtaposed with the high abundance of mature fish (Selgeby et al., 1995), the situation in Lake Ontario suggests a reduction in reproductive efficiency. This could result from mortality factors that may to a certain extent be density independent because recruitment has remained flat in the face of increasing spawner abundance. According to RESTORE, such factors are likely acting during the first year of life. Accordingly, the authors herin review the evidence that former barriers to lake trout reproduction in Lake Ontario that act as early-life-stage bottlenecks have been removed. In addition, the authors review other potential new barriers for which there has only recently been enough information to judge their relative importance.

Book chapter↗
USGS2002

Sea otter ( Enhydra lutris ) perspective: Part A. Sea otter population status and the process of recovery from the 1989 Exxon Valdez oil spill

Sea otter ( Enhydra lutris ) populations were severely affected by the 1989 Exxon Valdez oil spill in western Prince William Sound, AK, and had not fully recovered by 2000. Here we present results of population surveys and incorporate findings from related studies to identify current population status and factors affecting recovery. Between 1993 and 2000, the number of sea otters in the spill-area of Prince William Sound increased by about 600 to nearly 2700. However, at Knight Island, where oil exposure and sea otter mortality in 1989 approached 0.90, no increase has been observed. Sea otter reproduction was not impaired and the age and sex structure of animals captured are consistent with both intrinsic reproduction and immigration contributing to recovery. However, low resighting rates of marked animals at Knight Island compared to an unoiled reference area, and a high proportion of young animals in beach cast carcasses through 1998, suggest that the lack of recovery was caused by relatively poor survival or emigration of potential recruits. Significantly higher levels of cytochrome P4501A (CYP1A), a biomarker of hydrocarbons, were found in sea otters at Knight Island in 1996-98 compared to unoiled Montague Island, implicating oil effects in the lack of recovery at Knight Island. Delayed recovery does not appear to be directly related to food limitation. Although food availability was relatively low at both oiled and unoiled areas, we detected significant increases in sea otter abundance only at Montague Island, a finding inconsistent with food as a principal limiting factor. Persistent oil in habitats and prey provides a source of continued oil exposure and, combined with relatively low prey densities, suggests a potential interaction between oil and food. However, sea otters foraged more successfully at Knight Island and young females were in better condition than those at Montague Island. We conclude that progress toward recovery of sea otters in Prince William Sound is evident, but that in areas where initial oil effects were greatest, recovery may be constrained by residual spill effects, resulting in elevated mortality and emigration. It is evident that internal reproduction and immigration of juveniles has been the primary means of population recovery, as opposed to broad scale redistribution of adults from outside affected areas. The result is a recovery period protracted by long-term spill effects on survival and emigration and intrinsic limits to population growth.

Alaska↗