An orchid inventory and conservation project at Bosque de Paz Biological Reserve, Upper Rio Toro Valley, Alajuela, Costa Rica
No abstract available.
Upper Rio Toro Valley, Alajuela, Costa Rica↗
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Juvenile salmonid use of freshwater emergent wetlands in the floodplain and its implications for conservation management
A recent trend of enhancing freshwater emergent wetlands for waterfowl and other wildlife has raised concern about the effects of such measures on juvenile salmonids. We undertook this study to quantify the degree and extent of juvenile Pacific salmon Oncorhynchus spp. utilization of enhanced and unenhanced emergent wetlands within the floodplain of the lower Chehalis River, Washington, and to determine the fate of the salmon using them. Enhanced emergent wetlands contained water control structures that provided an outlet for fish emigration and a longer hydroperiod for rearing than unenhanced wetlands. Age‐0 and age‐1 coho salmon O. kisutch were the most common salmonid at all sites, enhanced wetlands having significantly higher age‐1 abundance than unenhanced wetlands that were a similar distance from the main‐stem river. Yearling coho salmon benefited from rearing in two enhanced wetland habitats, where their specific growth rate and minimum estimates of survival (1.43%/d by weight and 30%; 1.37%/d and 57%) were comparable to those in other side‐channel rearing studies. Dissolved oxygen concentrations decreased in emergent wetlands throughout the season and approached the limits lethal to juvenile salmon by May or June each year. Emigration patterns suggested that age‐0 and age‐1 coho salmon emigrated as habitat conditions declined. This observation was further supported by the results of an experimental release of coho salmon. Survival of fish utilizing emergent wetlands was dependent on movement to the river before water quality decreased or stranding occurred from wetland desiccation. Thus, our results suggest that enhancing freshwater wetlands via water control structures can benefit juvenile salmonids, at least in the short term, by providing conditions for greater growth, survival, and emigration.
Washington↗
Conservation genetics of Lake Superior brook trout: Issues, questions, and directions
Parallel efforts by several genetic research groups have tackled common themes relating to management concerns about and recent rehabilitation opportunities for coaster brook trout Salvelinus fontinalis in Lake Superior. The questions that have been addressed include the evolutionary and genetic status of coaster brook trout, the degree of relatedness among coaster populations and their relationship to riverine tributary brook trout populations, and the role and effectiveness of stocking in maintaining and restoring coasters to Lake Superior. Congruent genetic results indicate that coasters are an ecotype (life history variant) rather than an evolutionarily significant unit or genetically distinct strain. Regional structure exists among brook trout stocks, coasters being produced from local populations. Introgression of hatchery genes into wild populations appears to vary regionally and may relate to local population size, habitat integrity, and anthropogenic pressures. Tracking the genetic diversity and integrity associated with captive breeding programs is helping to ensure that the fish used for stocking are representative of their source populations and appropriate for rehabilitation efforts. Comparative analysis of shared samples among collaborating laboratories is enabling standardization of genotype scoring and interpretation as well as the development of a common toolkit for assessing genetic structure and diversity. Incorporation of genetic data into rehabilitation projects will facilitate monitoring efforts and subsequent adaptive management. Together, these multifaceted efforts provide comprehensive insights into the biology of coaster brook trout and enhance restoration options. ?? Copyright by the American Fisheries Society 2008.
Conference Paper↗
Ecology and conservation of a rare, old-growth-associated canopy lichen in a silvicultural landscape
Nephroma occultum Wetm. is a rare, epiphytic lichen associated with old-growth forests of northwestern North America. We describe its distribution, abundance, and habitat within the managed landscape of a southwestern Oregon watershed. Because this species is found mainly in the canopy, we used direct canopy access (tree climbing) in combination with ground (litter) searches for our surveys. We recommend this dual approach when confident determination of presence or absence of a canopy species is needed. Our surveys confirm that N. occultum is a rare old-growth associate within the area of this study, the southernmost extension of its known range. It was both rare across the landscape and uncommon in our primary study site, a 500 yr old stand. It was most often found growing close to the trunk on branches of large Pseudotsuga menziesii , but its distribution was sporadic even within an old-growth stand. The scarcity of very old stands, in combination with the limited ability of this species to disperse within and between stands, has likely contributed to its rarity within the watershed. Management for N. occultum should focus on populations and habitat needs rather than on individuals. Our calculations show that cutting with retention of individual trees surrounded by small buffers could result in the eventual loss of N. occultum from the study area.
Oregon↗
Archaic agencies, muddled missions, and conservation in the 21st century
No abstract available.
BioScience↗
Landscapes to riverscapes: bridging the gap between research and conservation of stream fishes
Rivers and streams, by their very nature long ribbons of aquatic habitat, are inherently difficult to study. Approaching the banks of a flowing-water (lotic) system, one can see only a short fragment of the entire stream, from one bend to another, and can gain little appreciation for important features that lie beyond view. Moreover, materials transported downstream by the flow, and organisms traveling up or down the hydraulic highway, are soon gone from the reach and the opportunity to study them is often lost. Lakes present their own challenges for study, but by contrast to streams, one can usually see large expanses from shore that encompass all major habitats needed for aquatic organisms to complete their life history, such as gravel shoals, beds of aquatic vegetation, and open water habitats
BioScience↗
A conservation plan for native fishes of the Lower Colorado River
The native fish fauna of the lower Colorado River, in the western United States, includes four “big-river” fishes that are federally listed as endangered. Existing recovery implementation plans are inadequate for these critically imperiled species. We describe a realistic, proactive management program founded on demographic and genetic principles and crafted to avoid potential conflicts with nonnative sport fisheries. In this program, native species would breed and their progeny grow in isolated, protected, off-channel habitats in the absence of nonnative fishes. Panmictic adult populations would reside in the main channel and connected waters, exchanging reproductive adults and repatriated subadults with populations occupying isolated habitats. Implementation of the plan would greatly enhance recovery potential of the four listed fishes.
BioScience↗
Tidal marshes: A global perspective on the evolution and conservation of their terrestrial vertebrates
Globally, tidal marshes are found in small pockets or narrow bands totaling only approximately 45,000 square kilometers. The combination of salinity, low floristic and structural complexity, and regular tidal inundation, as well as unpredictable catastrophic flooding, provides a unique selective environment that shapes local adaptations, including those that are morphological, physiological, demographic, and behavioral. Although tidal marshes support a low diversity of nonaquatic vertebrate species, a high proportion of these inhabitants, at least along North American coastlines, are restricted to or have subspecies restricted to tidal marshes. Tidal marshes and their endemic fauna face broad threats from a variety of human-caused environmental changes. Future research should focus on global inventories, intercontinental comparative work, and investigation to determine why almost all presently described endemic taxa appear to be found in North America.
BioScience↗
Migration stopovers and the conservation of arctic-breeding Calidrine sandpipers
Long-distance migration, one of the most physically demanding events in the animal kingdom, is well developed in many species of Charadriidae and Scolopacidae. Some shorebirds renowned for their extraordinary long-distance migrations, notably American Golden-Plover ( Pluvialis dominica ), Red Knot ( Calidris canutus rufa ), and White-rumped Sandpiper ( C. fuscicollis ), travel as many as 15,000 km between southern South American wintering grounds and Canadian Arctic breeding areas. Migration strategies of shorebirds vary in many aspects. There are remarkable accounts of shorebirds, such as northbound Red Knots, that stage in a few key sites for 2–3 weeks and lay on extensive body stores, then fly nonstop for distances of ≤2,500 km (Harrington 2001, Piersma et al. 2005). Less well known are the examples of populations that refuel only briefly at stopover sites, disperse broadly on the landscape, and fly shorter distances between sites (Skagen 1997, Haig et al. 1998, Warnock et al. 1998). This latter pattern applies to many long-distance migrant shorebirds that cross the interior plains of North America during spring and fall migrations. For them, interior wetland complexes provide critical refueling resources along the direct routes between summering and wintering grounds (Skagen et al. 1999). In this issue of The Auk, Krapu et al. (2006) describe patterns and implications of fat deposition by Semipalmated Sandpipers ( C. pusilla ), White-rumped Sandpipers, and Baird's Sandpipers ( C. bairdii ) refueling during northward migration across the prairies of mid-continental North America.
The Auk↗
Global rates of habitat loss and implications for amphibian conservation
A large number of factors are known to affect amphibian population viability, but most authors agree that the principal causes of amphibian declines are habitat loss, alteration, and fragmentation. We provide a global assessment of land use dynamics in the context of amphibian distributions. We accomplished this by compiling global maps of amphibian species richness and recent rates of change in land cover, land use, and human population growth. The amphibian map was developed using a combination of published literature and digital databases. We used an ecoregion framework to help interpret species distributions across environmental, rather than political, boundaries. We mapped rates of land cover and use change with statistics from the World Resources Institute, refined with a global digital dataset on land cover derived from satellite data. Temporal maps of human population were developed from the World Resources Institute database and other published sources. Our resultant map of amphibian species richness illustrates that amphibians are distributed in an uneven pattern around the globe, preferring terrestrial and freshwater habitats in ecoregions that are warm and moist. Spatiotemporal patterns of human population show that, prior to the 20 th century, population growth and spread was slower, most extensive in the temperate ecoregions, and largely exclusive of major regions of high amphibian richness. Since the beginning of the 20 th century, human population growth has been exponential and has occurred largely in the subtropical and tropical ecoregions favored by amphibians. Population growth has been accompanied by broad-scale changes in land cover and land use, typically in support of agriculture. We merged information on land cover, land use, and human population growth to generate a composite map showing the rates at which humans have been changing the world. When compared with the map of amphibian species richness, we found that many of the regions of the earth supporting the richest assemblages of amphibians are currently undergoing the highest rates of landscape modification.
Copeia↗
Habitat suitability and conservation of the Giant Gartersnake (Thamnophis gigas) in the Sacramento Valley of California
Resource managers often have little information regarding the habitat requirements and distribution of rare species. Factor analysis-based habitat suitability models describe the ecological niche of a species and identify locations where these conditions occur on the landscape using existing occurrence data. We used factor analyses to assess the suitability of habitats for Thamnophis gigas (Giant Gartersnake), a rare, threatened species endemic to the Central Valley of California, USA, and to map the locations of habitat suitable for T. gigas in the Sacramento Valley. Factor analyses indicated that the niche of T. gigas is composed of sites near rice agriculture with low stream densities. Sites with high canal densities and near wetlands also appeared suitable, but results for these variables were sensitive to potential sampling bias. In the Sacramento Valley, suitable habitats occur primarily in the central portion of the valley floor. Based upon the results of the factor analyses, recovery planning for T. gigas will require an on-the-ground assessment of the current distribution and abundance of T. gigas, maintaining the few remaining natural wetlands and the practice of rice agriculture in the Sacramento Valley, and studying the effects of agricultural practices and land use changes on populations of T. gigas. ?? 2010 by the American Society of Ichthyologists and Herpetologists.
Copeia↗
Reptile and amphibian diversity and abundance in an urban landscape: Impacts of fragmentation and the conservation value of small patches
Urbanization is a major contributor to habitat loss and fragmentation and is considered a global threat to biodiversity. We studied reptile and amphibian species diversity and abundance in a highly fragmented landscape adjacent to the second largest metropolitan area in the United States. Habitat patches in our study area were made up of remnant native vegetation surrounded by roads, housing, and other urban development. Species richness and diversity were positively associated with patch size, but patch age was not significantly associated with community characteristics. Four relatively common species were not detected in the small patches, indicating the possibility they had been extirpated by the time monitoring began, and six rarer species were not detected or detected only once in these patches. Although the patch size effect on species diversity was strong, we found that several of the small habitat patches had similar diversity to large patches, indicating potential value of these small habitat patches in protecting species as “microreserves.” In addition, one lizard species was found to be significantly more abundant in the smaller patches. To determine if abundance changed over time, we compared capture rates for four common lizards at the same sites ten years later. For three of the four species, abundance decreased over that period, specifically in the small patches. Although our long-term monitoring has confirmed that the full suite of herpetofauna is currently preserved in the study area overall, declines even in the common species over time hint at the potential severity of the threat of urbanization to rare species.
California↗
Unraveling the effects of sex and dispersal: Ozark big-eared bat (Corynorhinus townsendii ingens) conservation genetics
The Ozark big-eared bat (Corynorhinus townsendii ingens) is federally listed as endangered and is found in only a small number of caves in eastern Oklahoma and northwestern Arkansas. Previous studies suggested site fidelity of females to maternity caves; however, males are solitary most of the year, and thus specific information on their behavior and roosting patterns is lacking. Population genetic variation often provides the necessary data to make inferences about gene flow or mating behavior within that population. We used 2 types of molecular data: DNA sequences from the mitochondrial D loop and alleles at 5 microsatellite loci. Approximately 5% of the population, 24 males and 39 females (63 individuals), were sampled. No significant differentiation between 5 sites was present in nuclear microsatellite variation, but distribution of variation in maternally inherited markers differed among sites. This suggests limited dispersal of female Ozark big-eared bats and natal philopatry. Areas that experience local extinctions are unlikely to be recolonized by species that show strong site fidelity. These results provide a greater understanding of the population dynamics of Ozark big-eared bats and highlight the importance of cave protection relative to maintaining genetic integrity during recovery activities for this listed species. ?? 2005 American Society of Mammalogists.
Journal of Mammalogy↗
Low genetic diversity and minimal population substructure in the endangered Florida manatee: implications for conservation
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 of variance explained by between group variance. Although genetic issues, as inferred by neutral genetic markers, appear not to be critical at present, the Florida manatee continues to face demographic challenges due to anthropogenic activities and stochastic factors such as red tides, oil spills, and disease outbreaks; these can further reduce genetic diversity of the manatee population.
Journal of Mammalogy↗
Demographic response of Louisiana Waterthrush, a stream obligate songbird of conservation concern, to shale gas development
Shale gas development continues to outpace the implementation of best management practices for wildlife affected by development. We examined demographic responses of the Louisiana Waterthrush ( Parkesia motacilla ) to shale gas development during 2009–2011 and 2013–2015 in a predominantly forested landscape in West Virginia, USA. Forest cover across the study area decreased from 95% in 2008 to 91% in 2015, while the area affected by shale gas development increased from 0.4% to 3.9%. We quantified nest survival and productivity, a source–sink threshold, riparian habitat quality, territory density, and territory length by monitoring 58.1 km of forested headwater streams ( n = 14 streams). Across years, we saw annual variability in nest survival, with a general declining trend over time. Of 11 a priori models tested to explain nest survival ( n = 280 nests), 4 models that included temporal, habitat, and shale gas covariates were supported, and 2 of these models accounted for most of the variation in daily nest survival rate. After accounting for temporal effects (rainfall, nest age, and time within season), shale gas development had negative effects on nest survival. Population-level nest productivity declined and individual productivity was lower in areas disturbed by shale gas development than in undisturbed areas, and a source–sink threshold suggested that disturbed areas were more at risk of being sink habitat. Riparian habitat quality scores, as measured by a U.S. Environmental Protection Agency index and a waterthrush-specific habitat suitability index, differed by year and were negatively related to the amount of each territory disturbed by shale gas development. Territory density was not related to the amount of shale gas disturbance, but decreased over time as territory lengths increased. Overall, our results suggest a decline in waterthrush site quality as shale gas development increases, despite relatively small site-wide forest loss.
West Virginia↗
Spatial patterns in occupancy and reproduction of Golden Eagles during drought: Prospects for conservation in changing environments
We used a broad-scale sampling design to investigate spatial patterns in occupancy and breeding success of territorial pairs of Golden Eagles ( Aquila chrysaetos ) in the Diablo Range, California, USA, during a period of exceptional drought (2014–2016). We surveyed 138 randomly selected sample sites over 4 occasions each year and identified 199 pairs of eagles, 100 of which were detected in focal sample sites. We then used dynamic multistate modeling to identify relationships between site occupancy and reproduction of Golden Eagles relative to spatial variability in landscape composition and drought conditions. We observed little variability among years in site occupancy (3-yr mean = 0.74), but the estimated annual probability of successful reproduction was relatively low during the study period and declined from 0.39 (± 0.08 SE) to 0.18 (± 0.07 SE). Probabilities of site occupancy and reproduction were substantially greater at sample sites that were occupied by successful breeders in the previous year, indicating the presence of sites that were consistently used by successfully reproducing eagles. We found strong evidence for nonrandom spatial distribution in both occupancy and reproduction: Sites with the greatest potential for occupancy were characterized by rugged terrain conditions with intermediate amounts of grassland interspersed with patches of oak woodland and coniferous forest, whereas successful reproduction was most strongly associated with the amount of precipitation that a site received during the nesting period. Our findings highlight the contribution of consistently occupied and productive breeding sites to overall productivity of the local breeding population, and show that both occupancy and reproduction at these sites were maintained even during a period of exceptional drought. Our approach to quantifying and mapping site quality should be especially useful for the spatial prioritization of compensation measures intended to help offset the impacts of increasing human land use and development on Golden Eagles and their habitats.
California↗
California red-legged frog (Rana draytonii) movement and habitat use: Implications for conservation
Nonbreeding habitats are critically important for Rana draytonii, especially for individuals that breed in temporary bodies of water. We radiotracked 123 frogs to evaluate seasonal habitat use. Individual frogs were continuously tracked for up to 16 months. Some individuals remained at breeding ponds all year, but 66% of female and 25% of male frogs moved to nonbreeding areas, even when the breeding site retained water. Frogs at our main study site moved 150 m (median), roughly the distance to the nearest suitable nonbreeding area. The greatest straight-line distance traveled was 1.4 km, although the presumed distance traveled was 2.8 km. Females were more likely than males to move from permanent ponds (38% of females, 16% of males), but among dispersing frogs, males and females did not differ in distance moved. Some frogs left breeding sites shortly after oviposition (median = 12 days for females, 42.5 days for males), but many individuals remained until the site was nearly dry. Fog provided moisture for dispersal or migration throughout the summer. Our data demonstrate that maintaining populations of pond-breeding amphibians requires that all essential habitat components be protected; these include (1) breeding habitat, (2) nonbreeding habitat, and (3) migration corridors. In addition, a buffer is needed around all three areas to ensure that outside activities do not degrade any of the three habitat components.
California↗
Genetic characterization of Neotropical Jabiru Storks: Insights for conservation
Jabiru Stork (Jabiru mycteria is listed under Appendix I of CITES and considered threatened in Central America. The first population genetic analysis of Jabiru Storks was carried out using mitochondrial DNA (mtDNA) control region sequences (520 bp) and five heterologous microsatellite loci. Samples were collected from the field (N = 49) and museum skins (N = 22) in Central (mainly Belize, Nicaragua and Costa Rica) and South America (Colombia, Venezuela, Peru and Brazil). A decline of mtDNA diversity was observed in comparisons between past (N = 20) and present (N = 40) samples collected in Central America and northern South America. Similar levels of microsatellite loci diversity were observed among contemporary samples. Lower levels of mtDNA variability were observed in samples from Central America and northern South America when compared to the Brazilian Pantanal region. Significant levels of genetic differentiation were found between contemporary locations sampled, whereas non-significant results were observed for historic samples. The non-geographic association of haplotypes observed at the cladograms and the recent divergence times estimated between locations are indicative of an evolutionary history of a large population size with limited population structure. Reconnection of populations via increased gene flow, particularly in Central America, is recommended if genetic structure and status are to be restored.
Waterbirds↗