Current Population Size Research Articles

Genetic Structure, Diversity and Long Term Viability of a Medicinal Plant, Nothapodytes nimmoniana Graham. (Icacinaceae), in Protected and Non-Protected Areas in the Western Ghats Biodiversity Hotspot.

Background and QuestionThe harvesting of medicinal plants from wild sources is escalating in many parts of the world, compromising the long-term survival of natural populations of medicinally important plants and sustainability of sources of raw material to meet pharmaceutical industry needs. Although protected areas are considered to play a central role in conservation of plant genetic resources, the effectiveness of protected areas for maintaining medicinal plant populations subject to intense harvesting pressure remain largely unknown. We conducted genetic and demographic studies of Nothapodytes nimmoniana Graham, one of the extensively harvested medicinal plant species in the Western Ghats biodiversity hotspot, India to assess the effectiveness of protected areas in long-term maintenance of economically important plant species.Methodology/Principal FindingsThe analysis of adults and seedlings of N. nimmoniana in four protected and four non-protected areas using 7 nuclear microsatellite loci revealed that populations that are distributed within protected areas are subject to lower levels of harvesting and maintain higher genetic diversity (He = 0.816, Ho = 0.607, A = 18.857) than populations in adjoining non-protected areas (He = 0.781, Ho = 0.511, A = 15.571). Furthermore, seedlings in protected areas had significantly higher observed heterozygosity (Ho = 0.630) and private alleles as compared to seedlings in adjoining non-protected areas (Ho = 0.426). Most populations revealed signatures of recent genetic bottleneck. The prediction of long-term maintenance of genetic diversity using BOTTLESIM indicated that current population sizes of the species are not sufficient to maintain 90% of present genetic diversity for next 100 years.Conclusions/SignificanceOverall, these results highlight the need for establishing more protected areas encompassing a large number of adult plants in the Western Ghats to conserve genetic diversity of economically and medicinally important plant species.

Conservation of threatened goat breeds in India

India is a rich repository of goat genetic resources having 23 well-recognized goat breeds. These breeds have evolved through natural selection and selective breeding by rearers for adaptation to specific agro-ecological conditions. As the indigenous goat breeds of India display great variation in adaptability, productivity, feed utilization, disease resistance, etc. so conservation for unique characteristics of indigenous breeds are of great importance. The recognized breeds of Indian goat population are facing a greater threat due to lack of enforcement of proper breeding policy, inadequate number of breeding bucks, indiscriminate crossbreeding and intermixing among breeds with local animals etc. Considering the current population size, declining rate of population, loss of habitat and introduction of other breeds in the area, the threatened goat breeds are Jamunapari, Beetal, Jakhrana and Surti in the northwestern region, Sangamneri, Osmanabadi, Malabari and Attappady Black in the southern region, Ganjam in the eastern region, and Chegu and Changthangi in the temperate Himalayan region. Furthermore, the positions of several breeds are more or less vulnerable in their breeding tracts. Now, efforts have been made to conserve the indigenous goat breeds for their unique characteristics in their home tracts through in-situ and ex-situ conservation in different agroclimatic regions of India.

Fitting state–space models to seal populations with scarce data

Abstract We estimate temporal variation in fecundity, the reproduction rate, for Barents Sea and Greenland Sea harp seals using a state–space approach. A stochastic process model for fecundity is integrated with an age-structured population dynamics model and fit to available data for these two harp seal populations. Owing to scarceness of data, it is necessary to “borrow strength” from the Northwest Atlantic harp seal population in form of prior distributions on autocorrelation and variance in fecundity. Comparison is made to a simpler deterministic population dynamics model. The state–space model is more flexible and is able to account for the variations in the data. For Barents Sea harp seals, the state–space model gives a higher estimate of current population size but also a much higher associated uncertainty. In the Greenland Sea, the differences between the stochastic and deterministic models are much smaller.

Post-release monitoring of a critically endangered galliform subspecies,Francolinus bicalcaratus ayesha,in Morocco: a field study using playback call counts

The Double-spurred Francolin Francolinus bicalcaratus ayesha is a critically endangered galliform subspecies in Morocco. To improve the viability of this threatened population, 300 captive-bred francolins were released into the Didactic Lot of the Royal Moroccan Federation of Hunting, and post-release monitoring was conducted. In this study, we used playback call counts to assess differences in habitat use and temporal variations in vocal activity of Double-spurred Francolins. The number of male calls per point count was significantly higher in the wooden matorral (WM) than in the non-wooden matorral (MT). The male responses per point count also increased depending on date, reaching a maximum in the first 10 days of March. The pattern was similar in the two habitats, although the maximum average call rates were significantly different [WM = 1.575 (95% CI: 1.394–1.780), MT = 0.481 (95% CI: 0.393–0.589)]. We suggest that call counts collected during this period could be used to index the annual change of the released population in that area. Further researches are, however, needed to (1) estimate the current population size of the released francolins and (2) characterize the habitats used within this protected area.

Out of the darkness: the first comprehensive survey of the Critically Endangered Anjouan Scops Owl Otus capnodes

SummaryAlthough birds are among the best studied taxa, many of the globally threatened species lack the information required to fully assess their conservation status and needs. One such species is the Anjouan Scops Owl Otus capnodes which was presumed extinct until its rediscovery to science in 1992. Based on the limited extent and decline of the moist forests in the highlands of Anjouan in the Comoro Islands, a population size of only 100–200 pairs was estimated and the species was classified as ‘Critically Endangered’. The current study is the first comprehensive survey ever conducted on this species, and aimed to establish the current distribution and population size. Point counts with distance sampling were conducted across the agroforestry and forest zones of Anjouan in both a dry and wet season. A niche suitability model predicted the species distribution to be wider than expected with owls observed as low as 300 m altitude and in highly modified agroforestry habitats. However, the encounter rate in natural relatively undisturbed forest was significantly greater than in other habitats. The wider than expected geographic range of O. capnodes supports a possible downlisting of this species on the IUCN Red List to ‘Endangered’. Population size was found to be far greater than previously thought, at approximately 3,450 individual owls in the dry season and 5,450 in the wet season. These results show the importance of investing in robust surveys of poorly known and cryptic bird species, and provide up to date and important information for landscape scale conservation planning in the Comoros Islands.

Impact of habitat alteration on endemic Afromontane chameleons: evidence for historical population declines using hierarchical spatial modelling

AbstractAimWe map estimated historical population declines resulting from species‐specific models of sensitivity to habitat fragmentation for three forest‐dependent chameleons.LocationEast Usambara Mountains, Eastern Arc Mountains, Tanzania.MethodsWe surveyed three chameleon species (Rhampholeon spinosus,Rhampholeon temporalisandTrioceros deremensis) along 32.2 km of transects and used a hierarchical, distance‐sampling model to estimate densities. The model included habitat characteristics at the landscape (patch) and local (transect) scales while accounting for detectability. By analysing the model in a Bayesian framework, we were able to propagate error through the entire analysis and obtain exact solutions despite small sample sizes. We then used our estimated relationships between habitat and density to project chameleon population sizes across current and historical land cover maps of the study area (230 km2), giving an estimate of the impact of anthropogenic habitat alteration on these species.ResultsSpecies’ densities increased in larger patches and further from patch edges and varied seasonally. Local vegetation characteristics had significant relationships with expected chameleon densities, though effect sizes were small. Estimates of total current population sizes varied by two orders of magnitude among species, but each was 49–79% higher than detection‐naïve estimates. All three declined from estimated historical levels by approximately 60% in the study area, approximately one‐third more than would be expected from forest loss alone. Remaining populations of the study species are predominantly located in protected nature reserves, so the future of these species will likely be determined by the degree of protection offered by the nature reserves.Main conclusionsHabitat loss and fragmentation have greatly reduced forest‐dependent chameleon population sizes in the East Usambara Mountains. Populations of these species in other areas are experiencing higher rates of habitat loss. Efforts aimed at ensuring the efficacy of protected forests may be a key to conserving remaining populations.

Noninvasive genetic sampling allows estimation of capercaillie numbers and population structure in the Bohemian Forest

Wildlife conservation and management of endangered species requires reliable information on the size and structure of populations. One of the flagship species in European wildlife conservation is the forest-dwelling capercaillie (Tetrao urogallus), where several populations are endangered. In the Bohemian Forest, e.g., the population severely declined 30 years ago with only 100 birds remaining in 1985. Subsequently, breeding and release programs were conducted to supplement the local population. The current distribution and population size, however, remained unknown. With recent habitat changes and increasing recreational activities, a reliable population estimate to inform conservation plans was needed. A team of scientists and volunteers collected fresh capercaillie droppings covering an area of about 120,000 ha. We genotyped ten microsatellite loci to estimate the current population size and to determine the population’s spatial and genetic structure. Population size and density estimators revealed a population size of approximately 500 individuals, which is thus one of the two largest relict populations in the low mountain ranges of temperate Europe. The population clustering revealed gene flow across the entire study area. Several genotypes were documented with multiple recaptures at spatial distances between 10 and 30 km additionally corroborating gene flow across the entire landscape of the study area. Males were more closely related than females on small spatial scales up to 3 km, indicating lower dispersal rates in males. We conclude that the population currently appears to have a viable size and shows unrestricted gene flow across state borders and management units of the entire Bohemian Forest. However, long-term viability of this population requires a transboundary strategy to sustainably protect and monitor this isolated capercaillie population in Central Europe.

Recent population size, trends, and limiting factors for the double-crested cormorant in western North America

The status of the double-crested cormorant (Phalacrocorax auritus) in western North America was last evaluated during 1987-2003. In the interim, concern has grown over the potential impact of predation by double-crested cormorants on juvenile salmonids (Oncorhynchus spp.), particularly in the Columbia Basin and along the Pacif ic coast where some salmonids are listed for protection under the United States Endangered Species Act. Recent re-evaluations of double-crested cormorant management at the local, flyway, and federal level warrant further examination of the current population size and trends in western North America. We collected colony size data for the western population (British Columbia, Washington, Oregon, Idaho, California, Nevada, Utah, Arizona, and the portions of Montana, Wyoming, Colorado and New Mexico west of the Continental Divide) by conducting aircraft-, boat-, or ground-based surveys and by cooperating with government agencies, universities, and non-profit organizations. In 2009, we estimated approximately 31,200 breeding pairs in the western population. We estimated that cormorant numbers in the Pacific Region (British Columbia, Washington, Oregon, and California) increased 72% from 1987-1992 to circa 2009. Based on the best available data for this period, the average annual growth rate (l) of the number of breeding birds in the Pacific Region was 1.03, versus 1.07 for the population east of the Continental Divide during recent decades. Most of the increase in the Pacif ic Region can be attributed to an increase in thesize of the nesting colony on East Sand Island in the Columbia River estuary, which accounts for about 39% of all breeding pairs in the western population and is the largest known breeding colony for the species (12,087 breeding pairs estimated in 2009). In contrast, numbers of breeding pairs estimated in coastal British Columbia and Washington have declined by approximately 66% during this same period. Disturbance at breeding colonies by bald eagles (Haliaeetus leucocephalus) and humans are likely limiting factors on the growth of the western population at present. Because of differences in biology and management, the western population of double-crested cormorants warrants consideration as a separate management unitfrom the population east of the Continental Divide. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

Genetic effects of living in a highly polluted environment: the case of the silversideBasilichthys microlepidotus(Jenyns) (Teleostei: atherinopsidae) in the Maipo River basin, central Chile

AbstractFreshwater systems are one of the environments most impacted by human activity, with pollution being a highly important factor. In Chile, several rivers exhibit varied levels of pollution, one of which is the Maipo River basin where the city of Santiago is located. The silversideBasilichthys microlepidotus(Jenyns) is an endemic fish species that inhabits this basin, thus we hypothesized that pollution has affected gene diversity and migration in populations ofB. microlepidotusfrom the Maipo River basin. The aim of this study was to identify the population structure ofB. microlepidotusin this basin and to determine if the populations of the silverside inhabiting polluted sites present differences in gene diversity and gene flow compared to populations inhabiting non‐polluted areas. Using the variability of eight microsatellites, five populations of silverside were detected; three inhabiting non‐polluted sites and two inhabiting polluted sites. From this, it was inferred thatB. microlepidotushas been able to tolerate pollution in the Maipo River basin. No differences in gene diversity or migration were detected between polluted and non‐polluted sites but comparison with historical estimation revealed an increase in the current migration rate when all the data from the basin were compared. A reduction in current effective population size was also observed when compared to historical values, and this is probably due to river degradation. Despite the disappearance of other fish species recorded at this basin, our results suggest thatB. microepidotusis tolerant to pollution, thus indicating that native species respond differently to this environmental factor.

Population structure and genetic signs of population bottlenecks in the endangered Hawaiian tree snail Achatinella sowerbyana

The native Hawaiian tree snail Achatinella sowerbyana has, along with its remaining congeners, experienced drastic population reductions in the past century. The species is endemic to O’ahu, and currently persists in fragmented wild populations and in a captive breeding facility at the University of Hawai’i at Manoa. We used seven microsatellite loci to examine genetic diversity and population structure, to look for genetic effects of population reductions, and to estimate current effective population sizes of four sampling locations on O’ahu, Hawai’i. We also sought to test the genetic similarity of the captive snails to the wild samples. Our results show low levels of inbreeding, but relatively low levels of genetic diversity. Bottleneck tests identified bottlenecks at each of the four populations, and current effective population sizes ranged from 9 to 68, indicating that continued reductions in genetic diversity are likely due to drift. There was measurable structure among populations, including significant FST values between all sampling locations, and two main clusters, each containing two populations. Attempts to assign the captive bred individuals to wild populations indicated they were more closely related to the southern populations, but that they were divergent from any of the wild populations. Our results indicate that, although introduced predators and habitat fragmentation still threaten A. sowerbyana, genetic concerns must also be addressed in managing this species. Strategies that retain the highest amount of genetic diversity and that are mindful of the population structure detected will provide A. sowerbyana the best chance for persistence.

A new population of Darwin's fox (Lycalopex fulvipes) in the Valdivian Coastal Range

FindingsDarwin's fox (Lycalopex fulvipes Martin, 1837) is an en-demic of the temperate forests of the Coastal Rangeof southern Chile, that was reported by Charles Darwinin 1834 in southern Chiloe Island (42° S, 74° W; Martin1837). Initially known exclusively from that island, itwas considered both an insular subspecies of the chillafox (Lycalopex griseus Gray, 1837) (Housse 1953; Clutton-Brock et al. 1976) and a valid species (Martin 1837; Gay1947; Osgood 1943). In 1990, a mainland population wasreported at Nahuelbuta National Park (ca. 450 km northof Chiloe Island, 37° 47′ S, 72° 59′ W; Figure 1a) in sym-patry with the chilla and culpeo foxes (Lycalopex culpaeusMolina, 1782) (Jaksic et al. 1990; Medel et al. 1990; Jimenezet al. 1991). This supported its status as a valid spe-cies, later confirmed through genetic studies (Yahnkeet al. 1996). Though this canid uses diverse habitat types,it is highly associated with native forest (Medel et al. 1990;Jimenez et al. 1991; Jimenez 2007). The current popula-tion size is not precisely known, but it has been estimatedto be fewer than 600 individuals, 90% of them on ChiloeIsland (Jimenez and McMahon 2004; Jimenez et al. 2008).In light of its small population size and the vulnerabilityof remaining populations, Darwin's fox was classifiedas Critically Endangered (CR: C2a (ii); cf. IUCN 2012).The discontinuous distribution of Darwin's fox, however,raised questions regarding the existence of other popula-tions in under-explored intermediate areas (e.g., Vila et al.2004; Jimenez et al. 2008). Recently, Vila et al. (2004)genetically identified a Darwin's fox skin from PuntaChanchan (39° 21′ S, 73° 14′ W) and reported possiblesightings by local people there and at Fundo Chaihuin(40° 01′ S, 73° 25′ W), but failed to find evidence of livingindividuals. An additional dead individual was reportedfrom the nearby locality of Lastarria (Gorbea district,39° 11′ S, 72° 6′ W; D'Elia et al. 2013). These localitiesare halfway between the previously known populations(Figure 1a), suggesting that indeed the range is less dis-continuous than was previously suspected.Here we report camera-trap (Bushnell Trophy Cam,Bushnell Corporation, Overland Park, KS, USA) recordsof Darwin's foxes in three different protected areas inLos Rios region, which indeed confirm the existenceof an intermediate population (Figure 1b,c). These re-cords were obtained as part of two independent studiesand a monitoring program. One of the studies and themonitoring program were conducted in the ValdivianCoastal Reserve (VCR; 40° 02′ S, 73° 35′ W; 50,250 ha;Figure 1b) during February to May 2012 and throughout2012, respectively. The third study surveyed two pro-tected areas (Figure 1b): Oncol Park (ONC; 39° 42′ S,73° 18′ W; 753 ha; March to May 2012) and AlerceCostero National Park (ACP; 39° 59′ S, 73° 28′ W;24,694 ha; December 2012 to March 2013).We recorded Darwin's fox in nine different cameratraps (i.e., one or more photos per camera trap), three ineach protected area (Figure 1c,d,e). Records from ONCcame from transects within the park or close to itsborder, whereas records from ACP came from the high-est elevation within the park. In all these cases, photoswere obtained in areas of either old-growth forest ordense understory, with cameras that were baited withraw chicken and commercial lures (Minnesota BrandBobcat Urine, Caven's Violator-7 and Terminator lures;Minnesota Trapline Products Inc., Pennock, MN, USA).All records from the VCR came from cameras set in anarea located close to ACP, including native forests andeucalyptus plantations with dense understory (Figure 1b).We did not use lures in the VCR.Our records add to the skin reported from PuntaChanchan (Vila et al. 2004) and the parallel report of adead individual at the nearby locality of Lastarria (D'Elia

The Impact of Accelerating Faster than Exponential Population Growth on Genetic Variation

Current human sequencing projects observe an abundance of extremely rare genetic variation, suggesting recent acceleration of population growth. To better understand the impact of such accelerating growth on the quantity and nature of genetic variation, we present a new class of models capable of incorporating faster than exponential growth in a coalescent framework. Our work shows that such accelerated growth affects only the population size in the recent past and thus large samples are required to detect the models' effects on patterns of variation. When we compare models with fixed initial growth rate, models with accelerating growth achieve very large current population sizes and large samples from these populations contain more variation than samples from populations with constant growth. This increase is driven almost entirely by an increase in singleton variation. Moreover, linkage disequilibrium decays faster in populations with accelerating growth. When we instead condition on current population size, models with accelerating growth result in less overall variation and slower linkage disequilibrium decay compared to models with exponential growth. We also find that pairwise linkage disequilibrium of very rare variants contains information about growth rates in the recent past. Finally, we demonstrate that models of accelerating growth may substantially change estimates of present-day effective population sizes and growth times.

The effect of inbreeding rate on fitness, inbreeding depression and heterosis over a range of inbreeding coefficients.

Understanding the effects of inbreeding and genetic drift within populations and hybridization between genetically differentiated populations is important for many basic and applied questions in ecology and evolutionary biology. The magnitudes and even the directions of these effects can be influenced by various factors, especially by the current and historical population size (i.e. inbreeding rate). Using Drosophila littoralis as a model species, we studied the effect of inbreeding rate over a range of inbreeding levels on (i) mean fitness of a population (relative to that of an outbred control population), (ii) within-population inbreeding depression (reduction in fitness of offspring from inbred versus random mating within a population) and (iii) heterosis (increase in fitness of offspring from interpopulation versus within-population random mating). Inbreeding rate was manipulated by using three population sizes (2, 10 and 40), and fitness was measured as offspring survival and fecundity. Fast inbreeding (smaller effective population size) resulted in greater reduction in population mean fitness than slow inbreeding, when populations were compared over similar inbreeding coefficients. Correspondingly, populations with faster inbreeding expressed more heterosis upon interpopulation hybridization. Inbreeding depression within the populations did not have a clear relationship with either the rate or the level of inbreeding.

Management regime influences shrubland birds and habitat conditions in the Northern Appalachians, USA

ABSTRACTPopulation declines of birds that breed in early‐successional shrubland habitat are of great concern to conservationists throughout the northeastern United States. To help increase the efficiency and effectiveness of efforts to conserve these species and their habitats, we studied birds in temporary forest openings created through even‐aged timber harvest, and permanent wildlife openings maintained through mechanical treatment and prescribed burning in the Northern Appalachians, USA in 2010 and 2011. We assessed the effects of treatment method, time since last treatment, and retained tree cover on shrubland bird abundance and habitat conditions. Burned and mechanically treated wildlife openings differed only in grass and fern cover. Both types of wildlife openings had more grasses and forbs, and less bare ground than silvicultural openings. Six out of 8 focal bird species were less abundant in silvicultural openings than in wildlife openings. In contrast, abundance of only 1 species differed between burned and mechanically treated wildlife openings. Silvicultural openings supported the same species as wildlife openings, indicating that this management option could be used in place of more costly wildlife opening management. However, because birds were more abundant in wildlife openings, maintaining the current population size of shrubland birds under a management strategy based entirely on silviculture would require a 50–300% increase in the area of silvicultural openings, depending on the species. Individual species peaked in abundance at different times post treatment, indicating that managers must maintain a range of early‐successional conditions across the landscape to provide habitat for the entire suite of shrubland birds. Six species exhibited a negative relationship with the basal area of retained conifer cover, and 7 species with deciduous tree cover, indicating that the retention of overstory trees in openings reduced their utility to early‐successional birds. © 2014 The Wildlife Society, 2014.

Effective population size of korean populations.

Recently, new methods have been developed for estimating the current and recent changes in effective population sizes. Based on the methods, the effective population sizes of Korean populations were estimated using data from the Korean Association Resource (KARE) project. The overall changes in the population sizes of the total populations were similar to CHB (Han Chinese in Beijing, China) and JPT (Japanese in Tokyo, Japan) of the HapMap project. There were no differences in past changes in population sizes with a comparison between an urban area and a rural area. Age-dependent current and recent effective population sizes represent the modern history of Korean populations, including the effects of World War II, the Korean War, and urbanization. The oldest age group showed that the population growth of Koreans had already been substantial at least since the end of the 19th century.

Nitrogen Isotope Composition of Peat Samples as a Proxy for Determining Human Colonization of Islands

The Aleutian Islands comprise a unique ecosystem, providing nesting grounds and habitat for more than ten million seabirds. No doubt their numbers were even larger prior to the introduction of foxes and rats, invasive species that have shaped the current population sizes and distributions of bird-breeding colonies. Here we present evidence that the peopling of the Aleutian Islands had the same dramatic effect on seabird populations. Analyses of nitrogen stable isotopes in Shemya Island peat deposits revealed significant 15 N enrichment of layers formed cal. 4,700–2,800 yrs BP suggesting high seabird guano input at that time. Following this period there was a sharp decline in δ15 N that coincides with the first appearance of human settlement and reflects drastic reduction in seabird abundance. The isotope signature of marine-derived nitrogen vectored by seabirds is specific only for coastal peat deposits; neither 15 N enrichment nor decline was detected in inland peat deposits.

Genetic status and timing of a weevil introduction to Santa Cruz Island, Galapagos.

Successful invasive species can overcome or circumvent the potential genetic loss caused by an introduction bottleneck through a rapid population expansion and admixture from multiple introductions. We explore the genetic makeup and the timing of a species introduction to Santa Cruz Island in the Galápagos archipelago. We investigate the presence of processes that can maintain genetic diversity in populations of the broad-nosed weevil Galapaganus howdenae howdenae. Analyses of combined genotypes for 8 microsatellite loci showed evidence of past population size reductions through moment and likelihood-based estimators. No evidence of admixture through multiple introductions was found, but substantial current population sizes (N0 298, 95% credible limits 50-2300), genetic diversity comparable with long-established endemics (Mean number of alleles = 3.875), and lack of genetic structure across the introduced range (F ST = 0.01359) could suggest that foundations are in place for populations to rapidly recover any loss of genetic variability. The time estimates for the introduction into Santa Cruz support an accidental transfer during the colonization period (1832-1959) predating the spurt in human population growth. Our evaluation of the genetic status of G. h. howdenae suggests potential for population growth in addition to our field observations of a concurrent expansion in range and feeding preferences towards protected areas and endemic host plants.

Population decline in the Rustic Bunting Emberiza rustica in Norway

Since the expansion of the Rustic Bunting (Emberiza rustica) westwards in northern Europe during the 19th and 20th centuries, declines have been reported in Fennoscandia. The Norwegian population was 100-500 breeding pairs in 1994. We carried out censuses to detect Rustic Buntings in Norway during 2008-12, and compared these results with previous records to evaluate recent population changes. Transect censuses made along 15 km of optimal habitat (swamp forest along rivers) yielded 18 territories during 1972-78, but in 2008 we found only 5 territories, and none since 2011. We also detected Rustic Buntings in 21 of 74 previously-occupied sites (one or more records during 1963-2007). During the study period 2008-12, we recorded Rustic Buntings in 41 sites, with a maximum of 47 territories in 2008. However, from 2008 to 2012 we detected a decline of 82% (yearly decline of 34% ± 9%; 95% CI). Local extinctions occurred in at least 31 sites. The current known population size is 13 territories in 9 sites, and the true population size may be only slightly larger. About half of all territories were associated with beaver dams, but the rate of decline during 2008-12 did not depend on dams. Extinctions could be attributed to habitat loss or change in 9/53 sites (1 logging, 1 cultivation, and 7 loss of a beaver dam). We suggest that the population decline of Norwegian Rustic Buntings is due to factors operating during migration or in wintering areas.

Predicting Grizzly Bear Density in Western North America

Conservation of grizzly bears (Ursus arctos) is often controversial and the disagreement often is focused on the estimates of density used to calculate allowable kill. Many recent estimates of grizzly bear density are now available but field-based estimates will never be available for more than a small portion of hunted populations. Current methods of predicting density in areas of management interest are subjective and untested. Objective methods have been proposed, but these statistical models are so dependent on results from individual study areas that the models do not generalize well. We built regression models to relate grizzly bear density to ultimate measures of ecosystem productivity and mortality for interior and coastal ecosystems in North America. We used 90 measures of grizzly bear density in interior ecosystems, of which 14 were currently known to be unoccupied by grizzly bears. In coastal areas, we used 17 measures of density including 2 unoccupied areas. Our best model for coastal areas included a negative relationship with tree cover and positive relationships with the proportion of salmon in the diet and topographic ruggedness, which was correlated with precipitation. Our best interior model included 3 variables that indexed terrestrial productivity, 1 describing vegetation cover, 2 indices of human use of the landscape and, an index of topographic ruggedness. We used our models to predict current population sizes across Canada and present these as alternatives to current population estimates. Our models predict fewer grizzly bears in British Columbia but more bears in Canada than in the latest status review. These predictions can be used to assess population status, set limits for total human-caused mortality, and for conservation planning, but because our predictions are static, they cannot be used to assess population trend.

Current Distribution, Relative Abundance, and Landscape-Level Habitat Associations of the Cerulean Warbler (Setophaga cerulea) Along the Lower Roanoke River in North Carolina

Setophaga cerulea (Cerulean Warbler) has been inadequately monitored along the Roanoke River in North Carolina since a breeding population was discovered there in 1972. Our objectives were to estimate the Cerulean Warbler's current population size and distribution along the river, and evaluate landscape habitat characteristics in the Roanoke River Basin among areas used and unused by the same species. In May 2001 and 2011, we surveyed for singing male Cerulean Warblers, primarily by boat, along approximately 160 km of the Roanoke River from Weldon to Williamston in northeast North Carolina. We found Cerulean Warblers in three distinct groups along the Roanoke River during both survey years; however, we detected at least 32.4% fewer males in 2011 (n = 23) than in 2001 (n = 34). The landscape within 500 m of areas used by Cerulean Warblers had significanlty less crop cover, blackwater floodplain (i.e., swamp) forest, and variation in mean canopy height than unused landscapes we surveyed. These same differences existed at distances up to 1 km, but several additional dissimilarities became evident at this scale, including presence of more evergreen plantations and a greater fragmentation of the dominant forested land cover at used versus unused landscapes. We recommend continued monitoring of the Cerulean Warbler along the Roanoke River, increased habitat protection, and encourage an in-depth investigation into management strategies to sustain this population.