Species Of Management Concern Research Articles

Linking behavioral states to landscape features for improved conservation management.

A central theme for conservation is understanding how animals differentially use, and are affected by change in, the landscapes they inhabit. However, it has been challenging to develop conservation schemes for habitat‐specific behaviors.Here we use behavioral change point analysis to identify behavioral states of golden eagles (Aquila chrysaetos) in the Sonoran and Mojave Deserts of the southwestern United States, and we identify, for each behavioral state, conservation‐relevant habitat associations.We modeled behavior using 186,859 GPS points from 48 eagles and identified 2,851 distinct segments comprising four behavioral states. Altitude above ground level (AGL) best differentiated behavioral states, with two clusters of short‐distance movement behaviors characterized by low AGL (state 1 AGL = 14 m (median); state 2 AGL = 11 m) and two associated with longer‐distance movement behaviors and characterized by higher AGL (state 3 AGL = 108 m; state 4 AGL = 450 m).Behaviors such as perching and low‐altitude hunting were associated with short‐distance movements in updraft‐poor environments, at higher elevations, and over steeper and more north‐facing terrain. In contrast, medium‐distance movements such as hunting and transiting were over gentle and south‐facing slopes. Long‐distance transiting occurred over the desert habitats that generate the best updraft.This information can guide management of this species, and our approach provides a template for behavior‐specific habitat associations for other species of management concern.

Trophic ecology of a large-bodied marine predator, bluntnose sixgill shark Hexanchus griseus, inferred using stable isotope analysis

Identifying feeding patterns of large-bodied predators is necessary for predicting their potential effects on food web dynamics. However, diet information from stomach contents can be impractical to obtain because required sample sizes can be prohibitively large. In contrast, diet estimates obtained using Bayesian stable isotope mixing models require less sampling effort and can also reveal both population- and individual-level variation in diet. Here, we used an extensive stable isotope data set to evaluate the trophic role of bluntnose sixgill shark (Hexanchus griseus), a globally distributed species and among the largest sharks in the North Pacific. In total, 43 subadult sixgill sharks were sampled from Puget Sound, Washington, USA. Mixing model results indicated that the population feeds primarily on benthic fish and invertebrates (estimated median diet percentages: 33 and 35%, respectively). Further, the model indicated low individual variation in diets and that the feeding behavior of both individuals and the population as a whole tended towards generalism. Specifically, sixgill sharks appear to feed on prey groups approximately in proportion to their average biomass densities in the Puget Sound food web. As generalists, sixgill sharks are less likely to be affected by changes in the abundance of any single prey resource, and our results suggest they are unlikely to be important predators to at least some species of management concern. In addition, stable isotope data obtained opportunistically from an adult sixgill shark supports previously suggested ontogenetic movement patterns, whereby some adults make brief migrations into Puget Sound from outer coastal habitats, likely to birth, and pups feed, grow, and remain resident in Puget Sound for several years. Our findings provide insights into the trophic role of this important but understudied species and demonstrate how stable isotope analyses can further understanding of shark ecology.

Long-Term Trends in Ringed Sawback (Graptemys oculifera) Growth, Survivorship, Sex Ratios, and Population Sizes in the Pearl River, Mississippi

Effective management of long-lived species requires demographic and life-history data that are best acquired from long-term studies. The ringed sawback (Graptemys oculifera), endemic to the Pearl River watershed of Mississippi and Louisiana, is a species of management concern at both the state and federal levels. Population sizes, trapping success, basking counts, sex ratios, survivorship, and growth of this species were investigated at 5 sites on the Pearl River in Mississippi over a 25-yr period. Estimates of age at maturity were 4.6 yrs for males and 9.1 yrs for females. Mean annual survivorship estimates for males, females, and juveniles were 0.88, 0.93, and 0.69, respectively. Maximum longevity estimates were 48.8 yrs for males and 76.4 yrs for females. Average longevity estimates were 8.5 yrs for males and 13.9 yrs for females. The sex ratio of captured turtles was male-biased before 2000 but unbiased after 2000. Realized population growth estimates indicated that 4 populations were stable over the 25-yr period and 1 population had declined. Population estimates and basking counts trended downward through time at most sites. Trapping success after 2000 for all sites combined declined by 77%, 45%, and 25% for juveniles, males, and females, respectively. Taken together, these data indicate that 1 population of G. oculifera has declined, 3 appear to be in the initial stages of decline, and 1 is relatively stable. Additional monitoring of these populations will be necessary to determine if these trends continue into the future.

Feasibility of Passive Integrated Transponder and Acoustic Tagging for Endangered Adult Delta Smelt

AbstractConservation and recovery of endangered species requires timely and defensible data to predict their responses to management actions. In the Sacramento–San Joaquin Delta, the population of Delta Smelt Hypomesus transpacificus, a species of management concern, has declined to a record low. Alternative research strategies are now sought to determine the efficacy of management actions. In this study, we assessed the feasibility of tagging cultured adult Delta Smelt as a potential surrogate for wild fish in field experiments. Preliminary experiments determined that anesthesia of Delta Smelt in 35 mg/L AQUI‐S 20E for 4 min best facilitated tagging. The 28‐d survival of Delta Smelt (n = 39) intracoelomically injected with passive integrated transponder (PIT) tags (8.4 mm, 0.03 g) was high (95%) and did not differ from untagged control fish; tag retention was 97%. Survival of Delta Smelt with injected (n = 40) and surgically inserted (n = 40) dummy acoustic transmitters (15.0 mm, 0.22 g) was significantly lower than PIT‐tagged and control fish, with only 60% surviving tag injection and 50% surviving surgical tag insertion. Surviving fish had high tag retention (injected: 95%; surgically inserted: 100%). Although not quantified, observational data suggested that the swimming ability of fish with acoustic tags was impaired. These results indicate that cultured Delta Smelt injected with PIT tags provide resource managers with a readily available wild surrogate to examine management actions in the delta. However, acoustic tags, which provide more detailed information on movement patterns, must be made smaller to reduce effects on survival before they can be used successfully in Delta Smelt. Logistic regression suggested that achievement of high survival (>90%) would require a tag mass: body mass ratio below 0.02.Received January 27, 2016; accepted May 25, 2016 Published online September 13, 2016

Impacts of Fire on Snowshoe Hares in Glacier National Park, Montana, USA

AbstractForest fires fundamentally shape the habitats available for wildlife. Current predictions for fire under a warming climate suggest larger and more severe fires may occur, thus challenging scientists and managers to understand and predict impacts of fire on focal species, especially species of management concern. Snowshoe hares (Lepus americanus Erxleben) are a common and important prey animal in boreal forests and are the primary prey for the US federally threatened Canada lynx (Lynx canadensis Kerr), so understanding hare dynamics in post-fire landscapes is critical for managing lynx. We collected habitat and fecal pellet data from 114 sites across three natural burn treatments (mature forest, 1988 Red Bench burn, and 1994 Adair and Howling burns) to evaluate impacts of fire and fire-habitat interactions on snowshoe hare in Glacier National Park, Montana, USA. We found that hare numbers were low throughout the park, with hares absent at 17 % of surveyed sites and occurring at densities above 0.5 hares ha−1 (a commonly suggested threshold for supporting Canada lynx) at only 7 % of sites. Hare densities were variable but 10 to 20 times higher in regenerating lodgepole pine (Pinus contorta Douglas ex Loudon) stands of 1988 Red Bench burn compared to lodgepole stands in other burn treatments. In stands dominated by other tree species, we found little difference in hare densities across burn treatments. Regardless of burn history or dominant canopy type, percent canopy cover was positively associated with hare relative abundance. Hare densities also increased with percent understory cover up to 80 % cover, beyond which they began to decline. The regular occurrence of wildfires in Glacier National Park, with 2003 being a particularly large fire year (the largest since 1910), suggest that hare and lynx distribution and abundance within the park may shift substantially in the coming decades as these animals respond to changing spatiotemporal patterns of regenerating forest.

A model-based approach for investigation and mitigation of disease spillover risks to wildlife: Dogs, foxes and canine distemper in central India

Multi-host pathogens can pose a serious conservation threat when free-ranging domestic animal populations occur alongside susceptible populations of wild species. An example is canine distemper virus (CDV), which can occur at high prevalence in domestic dog (Canis familiaris) populations from which it may be transmitted (spillover) into wild carnivore populations. Effective management of such disease threats is hindered by our limited understanding of the the dynamics of interspecific CDV transmission in natural settings. We used a modeling approach to better understand CDV spillover threats to wild Indian foxes (Vulpes bengalensis) occurring in a protected grassland habitat in central India. An agent-based stochastic simulation model was built, and parameterized with data from ecological and epidemiological studies. Based on the sensitivity analyses of the model, the CDV incidence rate in dogs was most influenced by the proportion of roamer dogs in the dog population. The CDV incidence rate in dogs was also sensitive to the CDV introduction frequency in the dog population. The proportion of roamer dogs in the dog population also influenced the number of CDV spillover events. The basic reproductive number (R0) for CDV in the model fox population was 0.85, indicating that CDV could not be independently sustained in the fox population. We used the model to explore potential management strategies to mitigate the risk of CDV spillover. Vaccination of local dog populations was an ineffective disease control strategy, while fox vaccination was highly effective. Interventions potentially resulting in lower contact rates between dogs and foxes, like reduction in village dog density and restricting dog movements in fox habitat, implemented in a sustained and integrated manner would be most effective in mitigating disease threats to foxes. Such modeling approaches can be used to better understand disease threats for other species of management concern, and to contrast potential management interventions.

Activity Patterns of Allegheny Woodrats in Tennessee

Abstract Neotoma magister (Allegheny Woodrat) is a species of management concern throughout its range. Better knowledge regarding timing of activity may improve monitoring and conservation of the species. We used remote cameras to examine activity patterns of Allegheny Woodrats at 9 rock outcrops on Catoosa Wildlife Management Area, TN, February– October 2010. Woodrat activity was documented during all months of study. Highest levels of activity occurred during May and October, during the hours of 02:00–03:00, at <40% full moon illumination, and at minimum nightly temperatures of 5–10 °C. Focusing on periods of greatest activity (late spring and early fall during darker phases of the lunar cycle) may increase efficiency of monitoring ef forts for the species.

Low genetic diversity and minimal population substructure in the endangered Florida manatee: implications for conservation

Abstract Species of management concern that have been affected by human activities typically are characterized by low genetic diversity, which can adversely affect their ability to adapt to environmental changes. We used 18 microsatellite markers to genotype 362 Florida manatees (Trichechus manatus latirostris), and investigated genetic diversity, population structure, and estimated genetically effective population size (Ne). The observed and expected heterozygosity and average number of alleles were 0.455 ± 0.04, 0.479 ± 0.04, and 4.77 ± 0.51, respectively. All measures of Florida manatee genetic diversity were less than averages reported for placental mammals, including fragmented or nonideal populations. Overall estimates of differentiation were low, though significantly greater than zero, and analysis of molecular variance revealed that over 95% of the total variance was among individuals within predefined management units or among individuals along the coastal subpopulations, with only minor portions...

LETHALPROCYRNEAINFECTION IN A BLACK-BACKED WOODPECKER (PICOIDES ARCTICUS) FROM CALIFORNIA

The black-backed woodpecker (Picoides arcticus) is a species of management concern in California. As part of a study of black-backed woodpecker home range size and foraging ecology, nine birds in Lassen National Forest (Shasta and Lassen Counties, California) were radio-tracked during the 2011 breeding season. One of the marked birds was found dead after being tracked for a 10-wk period in which it successfully nested. A postmortem examination of the dead bird revealed that it was emaciated and autolyzed, with the presumptive cause being numerous spiruroid nematodes of the genus Procyrnea in the gizzard. This first observation of Procyrnea nematodes in a black-backed woodpecker is notable because the Procyrnea infection was considered lethal and because Procyrnea has been implicated in substantial die-offs in other bird species, including woodpeckers.

Factors Influencing Behavior of Wetland Birds in the Rainwater Basin during Spring Migration

As little is known about specific factors influencing wetland birds during migration, the effects of time period, hunting pressure, and year on wetland bird behavior were evaluated during spring migration. Avian behavior was quantified on 36–40 playa wetlands in the Rainwater Basin region of Nebraska, during springs 2002–2004. Multivariate analysis of variance was used to test for differences in behavior among time periods, hunting categories (closed to hunting, hunted wetlands in-season, and hunted wetlands post-season), and years for geese, dabbling ducks, diving ducks, and shorebirds, as well as among two species of management concern; Greater White-fronted Geese (Anser albifrons) and Northern Pintails (Anas acuta). Overall, goose behavior did not differ among time periods or years; however, a greater percentage of geese were observed feeding in wetlands closed to hunting (11%) than on hunted wetlands in-season (5%). A smaller percentage of dabbling ducks was observed feeding on hunted wetlands in-season (19%) than on wetlands closed to hunting (24%) or on hunted wetlands post-season (28%). Diving duck and shorebird behavior did not differ among time periods, years, or hunting categories. Although spring hunting was implemented to reduce the light goose population, it may also be negatively influencing habitat quality at migration stopover sites for geese and dabbling ducks. Managers should consider limiting spring hunting disturbance on temporary and seasonal wetlands, where dabbling ducks spend more time foraging, than on semi-permanent wetlands.

Grassland Bird use of Oak Barrens and Dry Prairies in Wisconsin

ABSTRACT: Grassland bird populations have declined more than any other group of birds in North America and are of conservation concern to state and federal agencies. We determined relative abundances of grassland birds in oak barrens and dry sand prairies—native habitat types rare in the state of Wisconsin. We also investigated the association of relative abundance, patch size, and patch vegetation. Our study was conducted May–July 2000–2002 on Fort McCoy Military Installation in Monroe County, Wisconsin. Fourteen grassland bird species were found in native habitat patches. Vesper sparrow (Pooecetes gramineus), grasshopper sparrow (Ammodramus savannarum), and field sparrow (Spizella pusilla) were the most abundant grassland bird species; all are species of management concern in Wisconsin. Of the most abundant species, only grasshopper sparrow relative abundance increased as patch size increased; vesper sparrow and field sparrow relative abundances decreased as patch size increased. Though found at lower r...

Genetic Analyses and Simulations of Larval Dispersal Reveal Distinct Populations and Directional Connectivity across the Range of the Hawaiian Grouper (Epinephelus quernus)

Integration of ecological and genetic data to study patterns of biological connectivity can aid in ecosystem-based management. Here we investigated connectivity of the Hawaiian grouperEpinephelus quernus, a species of management concern within the Main Hawaiian Islands (MHI), by comparing genetic analyses with simulated larval dispersal patterns across the species range in the Hawaiian Archipelago and Johnston Atoll. Larval simulations revealed higher dispersal from the MHI to the Northwestern Hawaiian Islands (NWHI) than in the opposite direction and evidence for a dispersal corridor between Johnston and the middle of the Hawaiian Archipelago. Genetic analyses using mitochondrial DNA (mtDNA) control region sequences and microsatellites revealed relatively high connectivity across the Hawaiian Archipelago, with the exception of genetically distinct populations and higher mtDNA diversity in the mid-Archipelago. These analyses support the preservation of the mid-archipelago as a source of genetic diversity and a region of connectivity with locations outside the Hawaiian Archipelago. Additionally, our evidence for directional dispersal away from the MHI lends caution to any management decisions that would rely on the NWHI replenishing depleted MHI stocks.

Nesting Success of Grassland Birds in Small Patches in an Agricultural Landscape

ABSTRACT. Although conservation theory argues for large habitat patches, most grasslands in the Midwest are small. To assess the influence of patch size and proximity to edges on nest survival, we monitored 816 nests of two grassland-nesting species, Dickcissel (Spiza americana) and Eastern Meadowlark (Sturnella magna), from 1996 to 2000 in a network of grasslands (3–142 ha) surrounded by cropland and small patches (<1 ha) of woody vegetation in southeastern Illinois. In this grassland-agriculture matrix, small patch size and proximity to cropland edges did not negatively affect nesting success of these two grassland species of management concern that commonly occur in small patches. Although larger grasslands are necessary to attract area-sensitive species, this work demonstrates the importance of even small grassland patches for nesting habitat in grassland birds. The landscape-scale density of grassland patches in this area may also contribute to the nesting success of these birds. Our results suggest ...

Acute, subacute, and subchronic exposure to 2A-DNT (2-amino-4,6-dinitrotoluene) in the northern bobwhite (Colinus virginianus)

2-Amino-4,6-dinitrotoluene (2A-DNT) is a metabolite of the explosive 2,4,6-trinitrotoluene (TNT) which is present in the soil at numerous U.S. Army installations as the result of TNT manufacture or training activities. Although many avian species are known to inhabit areas where 2A-DNT has been found in the environment, no published studies of the effects of 2A-DNT exposure in birds are available. In this study, we conducted an evaluation of the oral toxicity of 2A-DNT in a representative ground foraging species of management concern, the northern bobwhite (Colinus virginianus). Subacute (14 days) and subchronic (60 days) oral gavage exposure studies were conducted following determination of the median acute lethal dose (LD50 = 1167 mg/kg). In the subacute study, survival occurred at 50 mg/kg/day. This helped to determine dose groups for the subchronic study: 0, 0.5, 3, 14, and 30 mg 2A-DNT/kg body weight-d in corn oil. The lowest observed adverse effects level (LOAEL) was determined to be 14 mg/kg/day based on mortality, and the no observed adverse effects level (NOAEL) was determined to be 3 mg/kg/day based on lack of effects at this exposure level.

The impacts of energy development noise playback on lek attendance and behavior in greater sagegrouse.

The spread of human development has caused a dramatic increase in noise across the landscape. Recent studies suggest that noise may negatively impact wildlife, yet little is known about the causes and consequences of this impact. Furthermore, most previous studies have not been designed to isolate noise impacts from other confounding factors. This study is investigating the impacts of energy development noise on greater sage grouse (Centrocercus urophasianus), a species of management concern across western North America. Sage grouse are declining in areas of energy development and circumstantial evidence suggests that noise is a cause of this decline. To test this hypothesis, control leks and leks with experimentally‐introduced energy development noise were monitored. Results from three seasons of experimental noise playback will be presented, comparing lek attendance, territory selection, and display behavior between noise and control leks. This is the first long‐term playback experiment investigating the chronic impacts of noise on any wild population, offering a unique opportunity to experimentally address noise impacts on avian behavior and breeding site selection while informing conservation efforts for this species.

Roost Tree Use by Sympatric Rafinesque's Big-Eared Bats (Corynorhinus Rafinesquii) and Southeastern Myotis (Myotis Austroriparius)

Rafinesque's big-eared bats (Corynorhinus rafinesquii) and southeastern myotis (Myotis austroriparius) are uncommon throughout their range and are listed (informally) by the U.S. Fish and Wildlife Service as species of management concern. Much of the decline in numbers of these species can be linked to a loss of bottomland hardwood forests throughout their range, resulting in a loss of natural roost structures in many areas. We characterized day roosts of both species and determined differences in characteristics of roost trees in western Tennessee. Radio transmitters were attached to adult females of both species to aid in locating new roosts. Thirty-one roost trees were identified, with most (93.5%) being large hollow water tupelos (Nyssa aquatica). Only two roost trees were used by both species during the survey period and no simultaneous roosting was documented. Roost trees in our study typically had triangular-shaped basal openings and large diameters (129.2 ± 7.3 cm). A significant difference (P < 0.05) in roost-tree diameter was observed between trees used by the two bat species. Our study is the first to compare characteristics of tree roosts of sympatric populations of Rafinesque's big-eared bats and southeastern myotis. Results suggest that these species may have different preferences for roost trees.

EFFECTS OF SUBCHRONIC EXPOSURE TO 2,6-DINITROTOLUENE IN THE NORTHERN BOBWHITE (COLINUS VIRGINIANUS)

Explosives and their breakdown products are commonly found in soils at U.S. military installations. Many areas where these compounds are found represent useful habitat for ground-foraging birds. Because these birds likely are exposed to such compounds, we evaluated the oral toxicity of 2,6-dinitrotoluene (DNT) in a representative ground-foraging species of management concern. Adult male and female northern bobwhite (Colinus virginianus) were exposed to either 0, 5, 10, 40, or 60 mg/kg/d via gavage for 60 d (subchronic) following determination of the median acute lethal dose (320 mg/kg). Circulating levels of red blood cells and hemoglobin were significantly decreased in a dose-dependent manner; however, levels remained within normal ranges. Plasma concentrations of total protein, albumin, globulin, aspartate aminotransferase, and potassium, sodium, and chlorine ions were significantly decreased, and circulating levels of uric acid were significantly increased. Decreased body weight, enlarged gallbladders, edematous gastrointestinal tracts, pale kidneys, pale and fibrous livers, and loose stools were consistent observations. The effects found in the clinical chemistries taken together with histopathological abnormalities observed in sections of hepatic and renal tissue suggest that the liver and kidneys are major targets for 2,6-DNT. Oral exposures to 2,6-DNT appear to affect northern bobwhite in a manner similar to that of the other main DNT isomer, 2,4-DNT, but in more subtle ways, adversely affecting the gastrointestinal system and leading to diarrhea and, ultimately, emaciation. The lowest-observed-adverse-effect level is 40 mg/ kg/d based on hematological measures, and the no-observed-adverse-effect level is 10 mg/kg/d based on the absence of results indicative of adverse effects.

USING THE NORTH AMERICAN BREEDING BIRD SURVEY AS A TOOL FOR CONSERVATION: A CRITIQUE OF BART ET AL. (2004)

Bart et al. (2004) develop methods for predicting needed samples for estimation of long-term trends from count survey data, and they apply these methods to the North American Breeding Bird Survey (BBS). They recommend adding approximately 40% more survey routes in the BBS to allow for estimation of long-term (i.e., 20 year) trends for a collection of species. We critique several aspects of their analysis and suggest that their focus on long-term trends and expansion of the present survey design will provide limited benefits for conservation because it fails to either enhance the credibility of the survey or better tie the survey to regional management activities. A primary innovation claimed by Bart et al. (2004) is the incorporation of bias in estimation in study planning. We question the value of this approach, as it requires reliable estimates of range of future bias. We show that estimates of bias used by Bart et al. (2004) are speculative. Failure to obtain better estimates of this bias is likely to compromise the credibility of future analyses of the survey. We also note that the generic analysis of population trends that they provide is of questionable validity and is unlikely to be relevant for regions and species of management concern.

Changes in Breeding Bird Populations with Habitat Restoration in Northern Iowa

Native tallgrass prairie and wetland habitat in the Prairie Pothole Region of the United States have declined over the past two centuries. Bird communities using these habitats have also experienced widespread declines that are often attributed to severe habitat loss and fragmentation. We estimated the change, or turnover, in bird populations in the Eagle Lake Wetland Complex, Iowa, with ongoing grassland and wetland restoration by linking geographic information system data and bird surveys in different land cover types (hayland, pasture, restored grassland, restored wetland and rowcrop agriculture) during the 1999–2001 breeding seasons. Habitat restoration efforts primarily converted rowcrop agriculture and pastures into grassland and wetland habitat. Based on land conversion, abundances of most species have likely increased in the area, including many species of management concern. Yet a few species, such as killdeer (Charadrius vociferus), have probably decreased in abundance. This estimation approach and these estimates provided a critical first step for evaluating restoration efforts; however, information on demographic parameters, such as nesting success, in restored areas is needed for understanding how restoration ultimately affects bird populations.

Longleaf Pine Restoration: Implications for Landscape-Level Effects on Bird Communities in the Lower Gulf Coastal Plain

Abstract The longleaf pine (Pinus palustris) ecosystem of the southeastern United States is among the most heavily degraded of all ecosystems. Less than 1% of the original longleaf pine forests remain as old-growth stands. Eglin Air Force Base (Eglin) in northwest Florida contains the largest remaining extent of longleaf pine, but much of this habitat has been degraded through fire suppression, selective logging, and planting off-site species of pines. We examined the distribution of bird species among habitats during spring and fall 1994–1995 to assess the influence of large-scale habitat restoration on bird communities across the landscape. During both spring and fall, species richness and relative abundance of neotropical migrants were greatest in oak hammocks and riparian habitats. During spring, the abundance of resident species was greatest in barrier island scrub and flatwoods, but species richness of residents also was high in oak hammocks. During fall, both species richness and abundance of residents were greatest in oak hammocks and flatwoods. Analyses of abundance for individual species (both neotropical migrants and residents) suggested that each habitat examined was important for ≥1 species. An analysis examining the importance of habitats for conservation found that oak hammocks and riparian habitats were important for species of high management concern, but burned sandhills along with oak hammocks and riparian habitats were very important for species of the greatest management concern. Our results suggest that habitat modifications resulting from restoration of the longleaf pine ecosystem will benefit many species of management concern. Bird species negatively affected by habitat modifications for longleaf pine restoration were abundant in other habitats. South. J. Appl. For. 27(2):107–121.