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At least 775 records · Page 43Linked to original sources
USGS2010

Recruitment in a Colorado population of big brown bats: Breeding probabilities, litter size, and first-year survival

We used markrecapture estimation techniques and radiography to test hypotheses about 3 important aspects of recruitment in big brown bats (Eptesicus fuscus) in Fort Collins, Colorado: adult breeding probabilities, litter size, and 1st-year survival of young. We marked 2,968 females with passive integrated transponder (PIT) tags at multiple sites during 2001-2005 and based our assessments on direct recaptures (breeding probabilities) and passive detection with automated PIT tag readers (1st-year survival). We interpreted our data in relation to hypotheses regarding demographic influences of bat age, roost, and effects of years with unusual environmental conditions: extreme drought (2002) and arrival of a West Nile virus epizootic (2003). Conditional breeding probabilities at 6 roosts sampled in 2002-2005 were estimated as 0.64 (95% confidence interval [95% CI] = 0.530.73) in 1-year-old females, but were consistently high (95% CI = 0.940.96) and did not vary by roost, year, or prior year breeding status in older adults. Mean litter size was 1.11 (95% CI = 1.051.17), based on examination of 112 pregnant females by radiography. Litter size was not higher in older or larger females and was similar to results of other studies in western North America despite wide variation in latitude. First-year survival was estimated as 0.67 (95% CI = 0.610.73) for weaned females at 5 maternity roosts over 5 consecutive years, was lower than adult survival (0.79; 95% CI = 0.770.81), and varied by roost. Based on model selection criteria, strong evidence exists for complex roost and year effects on 1st-year survival. First-year survival was lowest in bats born during the drought year. Juvenile females that did not return to roosts as 1-year-olds had lower body condition indices in late summer of their natal year than those known to survive. ?? 2009 American Society of Mammalogists.

Journal of Mammalogy↗
USGS2011

Black-footed ferrets and Siberian polecats as ecological surrogates and ecological equivalents

Ecologically equivalent species serve similar functions in different communities, and an ecological surrogate species can be used as a substitute for an equivalent species in a community. Siberian polecats (Mustela eversmanii) and black-footed ferrets (M. nigripes) have long been considered ecological equivalents. Polecats also have been used as investigational surrogates for black-footed ferrets, yet the similarities and differences between the 2 species are poorly understood. We contrasted activity patterns of radiotagged polecats and ferrets released onto ferret habitat. Ferrets tended to be nocturnal and most active after midnight. Polecats were not highly selective for any period of the day or night. Ferrets and polecats moved most during brightly moonlit nights. The diel activity pattern of ferrets was consistent with avoidance of coyotes (Canis latrans) and diurnal birds of prey. Similarly, polecat activity was consistent with avoidance of red foxes (Vulpes vulpes) in their natural range. Intraguild predation (including interference competition) is inferred as a selective force influencing behaviors of these mustelines. Examination of our data suggests that black-footed ferrets and Siberian polecats might be ecological equivalents but are not perfect surrogates. Nonetheless, polecats as surrogates for black-footed ferrets have provided critical insight needed, especially related to predation, to improve the success of ferret reintroductions. ?? 2011 American Society of Mammalogists.

Journal of Mammalogy↗
USGS2011

Mortality of Siberian polecats and black-footed ferrets released onto prairie dog colonies

Black-footed ferrets ( Mustela nigripes ) likely were extirpated from the wild in 1985–1986, and their repatriation depends on captive breeding and reintroduction. Postrelease survival of animals can be affected by behavioral changes induced by captivity. We released neutered Siberian polecats ( M. eversmanii ), close relatives of ferrets, in 1989–1990 on black-tailed prairie dog ( Cynomys ludovicianus ) colonies in Colorado and Wyoming initially to test rearing and reintroduction techniques. Captive-born polecats were reared in cages or cages plus outdoor pens, released from elevated cages or into burrows, and supplementally fed or not fed. We also translocated wild-born polecats from China in 1990 and released captive-born, cage-reared black-footed ferrets in 1991, the 1st such reintroduction of black-footed ferrets. We documented mortality for 55 of 92 radiotagged animals in these studies, mostly due to predation (46 cases). Coyotes ( Canis latrans ) killed 31 ferrets and polecats. Supplementally fed polecats survived longer than nonprovisioned polecats. With a model based on deaths per distance moved, survival was highest for wild-born polecats, followed by pen-experienced, then cage-reared groups. Indexes of abundance (from spotlight surveys) for several predators were correlated with mortality rates of polecats and ferrets due to those predators. Released black-footed ferrets had lower survival rates than their ancestral population in Wyoming, and lower survival than wild-born and translocated polecats, emphasizing the influence of captivity. Captive-born polecats lost body mass more rapidly postrelease than did captive-born ferrets. Differences in hunting efficiency and prey selection provide further evidence that these polecats and ferrets are not ecological equivalents in the strict sense.

Journal of Mammalogy↗
USGS2004

Analysis of predator movement in prairie landscapes with contrasting grassland composition

Mammalian predation influences waterfowl breeding success in the U.S. northern Great Plains, yet little is known about the influence of the landscape on the ability of predators to find waterfowl nests. We used radiotelemetry to record nightly movements of red foxes ( Vulpes vulpes ) and striped skunks ( Mephitis mephitis ) in two 41.4-km 2 study areas in North Dakota. Study areas contained either 15–20% grassland (low grassland composition) or 45–55% grassland (high grassland composition). Grasslands included planted cover, pastureland, and hayland. We predicted that the type and composition of cover types in the landscape would influence both predator movement across the landscape (as measured by the fractal dimension and displacement ratio) as well as localized movement (as measured by the rate of movement and turning angle between locations) within patches of different cover types. Red fox movements were straighter (lower fractal dimensions and higher displacements) across landscapes with a low grassland composition, indicating directed movement between the more isolated patches of planted cover. Striped skunk movements did not differ between landscape types, illustrating their movement along wetland edges, which had similar compositions in both landscape types. The high variability in turning angles by red fox in planted cover and pastureland in both landscape types is consistent with restricted-area foraging. The high rate of movement by red foxes in planted cover and by striped skunks in wetland edges suggests that spatial memory may influence movement patterns. Understanding the behavior of predators in fragmented prairie landscape is essential for managing breeding habitat for grassland birds and for predicting the spatial and temporal dynamics of predators and their prey.

North Dakota↗
USGS2010

Release of infectious cells from epidermal ulcers in Ichthyophonus sp.–infected Pacific Herring (Clupea pallasii): Evidence for multiple mechanisms of transmission

A common clinical sign of ichthyophoniasis in herring and trout is “sandpaper” skin, a roughening of the epidermis characterized by the appearance of small papules, followed by ulceration and sloughing of the epithelium; early investigators hypothesized that these ulcers might be a means of transmitting the parasite, Ichthyophonus sp ., without the necessity of ingesting an infected host. We examined the cells associated with the epidermal lesions and confirmed that they were viable Ichthyophonus sp. cells that were readily released from the skin into the mucous layer and ultimately into the aquatic environment. The released cells were infectious when injected into the body cavity of specific-pathogen-free herring. Our hypothesis is that different mechanisms of transmission occur in carnivorous and planktivorous hosts: Planktonic feeders become infected by ingestion of ulcer-derived cells, while carnivores become infected by ingestion of whole infected fish.

Journal of Parasitology↗
USGS2009

Behavior and reproductive success of rock sandpipers breeding on the Yukon-Kuskokwim river delta, Alaska

We studied Rock Sandpiper ( Calidris ptilocnemis ) breeding behavior and monitored reproductive success from 1998 to 2005 on the Yukon-Kuskokwim River Delta, Alaska, USA. We banded 24 adults and monitored 45 nests. Annual return rate of adults ranged between 67 and 100%. Six pairs of Rock Sandpipers bred at our study site for ≥2 years, and among these we did not observe mate change (i.e., when both members of a pair returned and each mated with a new individual). Nests were typically initiated by mid-May and 53% of females laid second clutches if first clutches were lost through mid-June. Males regularly incubated clutches during the morning (0800–1259 hrs AKDT) and afternoon (1300–1759 hrs) and rarely during the evening (1800– 2300 hrs), whereas female incubation was relatively consistent throughout the day. Apparent nest success (percent of known nests successfully hatching >1 chick) among first and second nests was 19 and 44%, respectively ( n = 45). A minimum of 44% of hatching nests fledged at least one young. Males cared for young but half of females deserted mate and brood 1–7 days post-hatch. This first description of North American Rock Sandpiper breeding behavior from a color-marked population complements previous work on this species on the Chukotsky Peninsula, Russia.

Wilson Journal of Ornithology↗
USGS2011

Interactions of raptors and Lesser Prairie-Chickens at leks in the Texas Southern High Plains

We examined behavioral interactions of raptors, Chihuahuan Ravens ( Corvus cryptoleucus ), and Lesser Prairie-Chickens ( Tympanuchus pallidicinctus ) at leks in the Texas Southern High Plains. Northern Harriers ( Circus cyaneus ) and Swainson's Hawks ( Buteo swainsoni ) were the most common raptors observed at leks. Only 15 of 61 (25%) raptor encounters at leks (0.09/hr) resulted in a capture attempt (0.02/hr). Mean (± SD) time for Lesser Prairie-Chickens to return to lekking behavior following a raptor encounter was 4.2 ± 5.5 min suggesting the disturbance had little influence on lekking behaviors. Lesser Prairie-Chickens engaged in different escape behaviors depending on raptor species and, generally, did not respond to ravens suggesting they are able to assess different predation risks. The raptors in our study area posed little predation risk to lekking prairie-chickens. Behavioral disturbance at leks appears minimal due to the lack of successful predation events, low raptor encounter rates, and short time to return to lekking behavior.

Texas↗
USGS2013

Breeding biology of an afrotropical forest understory bird community in northeastern Tanzania

Many aspects of the breeding biology of Afrotropical forest birds are poorly known. Here we provide a description based on the monitoring of 1461 active nests over eight breeding seasons about one or more aspects of the breeding biology for 28 coexisting understory bird species on the Amani Plateau in the East Usambara Mountains, Tanzania. Mean nest height and mean distance of nest from forest edge varied widely among species with most species constructing nests across a broad vertical and forest edge to interior gradient. However, there were important exceptions with all sunbird species and several dove and waxbill species constructing nests in close proximity to the forest edge. For 17 common species for which we recorded two or more active nests, mean clutch size across species was 1.9 eggs per clutch, the lowest site-specific mean clutch size yet reported for a tropical forest bird community. For nine bird species, a subset of the 17 common species, length of breeding season, defined as the difference between the earliest and latest recorded incubation onset date, ranged from 88–139 days. Most of these nine species displayed a unimodal distribution in incubation onset dates across a breeding season which extended from the end of August through middle January. In summary, a wide variation exists in most aspects of the breeding biology within an understory forest bird community in the East Usambara Mountains.

Wilson Journal of Ornithology↗
USGS2016

Reproductive success and habitat characteristics of Golden-winged Warblers in high-elevation pasturelands

The Golden-winged Warbler ( Vermivora chrysoptera ) is one of the most rapidly declining vertebrate species in the Appalachian Mountains. It is the subject of extensive range-wide research and conservation action. However, little is known about this species' breeding ecology in high-elevation pasturelands, a breeding habitat with conservation potential considering the U.S. Natural Resource Conservation Service's Working Lands for Wildlife program targeting private lands in the Appalachian Mountains. We located 100 nests of Golden-winged Warblers in pastures in and around the Monongahela National Forest in West Virginia during 2008&ndash;2012. Daily nest survival rate (mean &plusmn; SE = 0.962 &plusmn; 0.006), clutch size (4.5 &plusmn; 0.1), and number of young fledged per nest attempt (2.0 &plusmn; 0.2) and successful nest (4.0 &plusmn; 0.1) fell within the range of values reported in other parts of the species' range and were not significantly affected by year or the presence/absence of cattle grazing. Classification tree analysis revealed that nests were in denser vegetation (&ge;52%) and closer to forest edges (<36.0 m) and shrubs (<7.0 cm) than random locations within the male's territory. Successful nests had significantly more woody cover (&ge;9%) within 1 m than failed nests. Our results suggest that cattle grazing at 1.2&ndash;2.4 ha of forage/animal unit with periodic mowing can create and maintain these characteristics without interfering with the nesting of Golden-winged Warblers. High-elevation pasturelands may provide a refuge for remaining populations of Golden-winged Warblers in this region.

Wilson Journal of Ornithology↗
USGS2021

Songbird use of interior and edge floodplain forest sites along the Upper Mississippi River, USA, during spring migration and breeding seasons

Floodplain forests of large rivers in the midwestern United States are naturally fragmented by sloughs, backwaters, wetlands, and shrub carr. On the highly altered Upper Mississippi River (UMR), resource managers want to protect and manage floodplain forests to benefit forest “interior” bird species. To discover bird relations with interior and edge floodplain forest, we characterized bird assemblages during spring migration and breeding season in 3 forest types: habitat in the interior of forest areas > 100 m from an edge, edges associated with interior areas, and other areas of forest not associated with an interior area (random sites) on the UMR between Hastings and Red Wing, Minnesota. The random sites represent the majority of UMR floodplain forest area because only a small percentage of forest occurs >100 m from edge. Estimated habitat characteristics did not differ among interior, edge, and random sites. Bird relative abundance, species richness, diversity, assemblage composition, and detections of all but one species (in spring) did not differ among interior, edge, and random sites during both seasons. Our results suggest a homogeneous bird assemblage across UMR floodplain forest in the study area during spring migration and the breeding season, and that individual forest bird species do not seem to be more abundant in interior or edge areas as we defined them.

Minnesota, Wisconsin↗
USGS2008

Prominent pancreatic endocrinopathy and altered control of food intake disrupt energy homeostasis in prion diseases

Prion diseases are fatal neurodegenerative diseases that can induce endocrinopathies. The basis of altered endocrine function in prion diseases is not well understood, and the purpose of this study was to investigate the spatiotemporal relationship between energy homeostasis and prion infection in hamsters inoculated with either the 139H strain of scrapie agent, which induces preclinical weight gain, or the HY strain of transmissible mink encephalopathy (TME), which induces clinical weight loss. Temporal changes in body weight, feed, and water intake were measured as well as both non-fasted and fasted concentrations of serum glucose, insulin, glucagon, ??-ketones, and leptin. In 139H scrapie-infected hamsters, polydipsia, hyperphagia, non-fasted hyperinsulinemia with hyperglycemia, and fasted hyperleptinemia were found at preclinical stages and are consistent with an anabolic syndrome that has similarities to type II diabetes mellitus and/or metabolic syndrome X. In HY TME-infected hamsters, hypodipsia, hypersecretion of glucagon (in both non-fasted and fasted states), increased fasted ??-ketones, fasted hypoglycemia, and suppressed non-fasted leptin concentrations were found while feed intake was normal. These findings suggest a severe catabolic syndrome in HY TME infection mediated by chronic increases in glucagon secretion. In both models, alterations of pancreatic endocrine function were not associated with PrPSc deposition in the pancreas. The results indicate that prominent endocrinopathy underlies alterations in body weight, pancreatic endocrine function, and intake of food. The prion-induced alterations of energy homeostasis in 139H scrapie- or HY TME-infected hamsters could occur within areas of the hypothalamus that control food satiety and/or within autonomic centers that provide neural outflow to the pancreas. ?? 2008 Society for Endocrinology.

Journal of Endocrinology↗
USGS1998

Estimating relative abundance from count data

Much of the available information on large-scale patterns of animal abundance is based on count surveys. The data provided by such surveys are often influenced by nuisance factors affecting the numbers of animals counted, but unrelated to population size. Temporal and spatial patterns in nuisance factors may exist, causing simple summaries of counts to give a misleading view of patterns in population size. We develop models for count data that allows the incorporation of such factors, and describe methods for estimating spatial patterns of relative abundance from counts. We carry out spatial analyses of North American Breeding Bird Survey data, in which observer ability is a nuisance parameter nested within sites. In light of evidence that new observers tend to count more birds than the observers they replace, we model observer ability as a random effect with mean depending on observer initiation year.

Austrian Journal of Statistics↗
USGS2014

Editors are editors, not oracles

Farji-Brener and Kitzberger (2014; hereafter FBK) resurrect the issues of Farji-Brener (2007) concerning manuscripts that are submitted to journals but that are not sent out for peer review: a process we call “reject following editorial review” (RFER). We thank FBK for reviving discussion about this important topic as new challenges, including new publication outlets, peer-review models, and an increasingly complex and voluminous scientific literature, are emerging across the publication landscape. While we disagree with FBK's perspective and conclusions, we recognize that this discussion can help to improve editorial and publication processes, and we welcome the opportunity to inform the ecological community about the current status of editorial practice at ESA journals.

Bulletin of the Ecological Society of America↗
USGS2005

A note on the comparative turbidity of some estuaries of the Americas

Field data from 27 estuaries of the Americas are used to show that, in broad terms, there is a large difference in turbidity between the analyzed east and west-coast estuaries and that tidal range and tidal length have an important influence on that turbidity. Generic, numerical sediment-transport modeling is used to illustrate this influence, which exists over a range of space scales from, e.g., the Rogue River Estuary (few km, few mg l-1) to the Bay of Fundy (hundreds of km, few g l-1). The difference in Pacific and Atlantic seaboard estuarine turbidity for the analyzed estuaries is ultimately related to the broad-scale geomorphology of the two continents.

Journal of Coastal Research↗
USGS2006

Renesting by dusky Canada geese on the Copper River Delta, Alaska

The population of dusky Canada geese ( Branta canadensis occidentalis ; hereafter duskies) breeding on the Copper River Delta (CRD), Alaska, USA, has been in long-term decline, largely as a result of reduced productivity. Estimates of renesting rates by duskies may be useful for adjusting estimates of the size of the breeding population derived from aerial surveys and for understanding population dynamics. We used a marked population of dusky females to obtain estimates of renesting propensity and renesting interval on the CRD, 1999&ndash;2000. Continuation nests, replacement nests initiated without a break in the laying sequence, resulted only after first nests were destroyed in the laying stage with &le;4 eggs laid. Renesting propensity declined with nest age from 72% in mid-laying to 30% in early incubation. Between first nests and renests, mean interval was 11.9 &plusmn; 0.6 days, mean distance was 74.5 m (range 0&ndash;214 m), and clutch size declined 0.9 &plusmn; 0.4 eggs. We incorporated our renesting estimates and available estimates of other nesting parameters into an individual-based model to predict the proportion of first nests, continuation nests, and renests, and to examine female success on the CRD, 1997&ndash;2000. Our model predicted that 19&ndash;36% of nests each year were continuation nests and renests. Also, through 15 May (the approx. date of breeding ground surveys), 1.1&ndash;1.3 nests were initiated per female. Thus, the number of nests per female would have a significant, though relatively consistent, effect on adjusting the relation between numbers of nests found on ground surveys versus numbers of birds seen during aerial surveys. We also suggest a method that managers could use to predict nests per female using nest success of early nests. Our model predicted that relative to observed estimates of nest success, female success was 32&ndash;100% greater, due to replacement nests. Thus, although nest success remains low, production for duskies was higher than previously thought. For dusky Canada geese, managers need to consider both continuation nests and renests in designing surveys and in calculating adjustment factors for the expansion of aerial survey data using nest densities.

Alaska↗
USGS1979

Risk preferences and flood insurance

A detailed theoretical model characterizing the individual's decision to purchase flood insurance is specified and the magnitude of the risk parameter is estimated using data based on transactions of flood insurance purchases. Empirical results for several samples of this subset of the general population indicated that consumers exhibited a relatively uniform degree of risk aversion across various localities where different hydrologic and economic conditions prevailed. While the estimates presented should not be directly extrapolated to the entire population located in a flood prone area, they provide evidence that parameters determining an individual's and/or community's willingness to pay for flood protection can be measured.

American Journal of Agricultural Economics↗
USGS1986

Habitat use and terrestrial activity by red tree voles ( Arborimus longicaudus ) in Oregon

Several species of vertebrates may find optimal habitat for breeding, nesting, or foraging in old-growth (>200 years old) confierous forests in the Pacific Northwest. Old-growth forests are economically valuable, however, and most unprotected stands will be cut within 40 years (Franklin et al., 1981). Meslow et al. (1981) and Raphael (1984) identified a critical need to document habitat use and establish the relationship of wildlife species in these forests. In 1983, we operated arrays of pitfall traps for six months to investigate habitat use by terrestrial herpetofauna and small mammals in four age classes of Douglas-fir ( Pseudotsuga menziesii ) forest in and near the H. J. Andrews Experimental Forest, Linn and Lane counties, Oregon. Red tree voles, Arborimus longicaudus , were among the mammals captured. This species is considered to find optimum habitat in old-growth forests (Franklin et al., 1981; Meslow et al., 1981), but quantitative data on the local occurrence of the species are lacking. Here we report on habitat use by A. longicaudus and document terrestrial activity for this presumably arboreal species. A pitfall array was located in each of 18 stands dominated by Douglas-fir. Each array consisted of two sets of three 5-m aluminum drift fences each with pitfall traps (No. 10 tin cans; 6.4 l in volume) at the ends of the fences (see Bury and Raphael, 1983). The 18 stands represented four successional stages based on estimated age: 3 pre-canopy (clear cuts 5-9 years old), 3 young (30-69 years), 4 mature (76-150 years), and 8 old-growth (195-450 years). Additionally, old-growth stands were ranked on a general moisture gradient (wet, mesic, or dry) based on aspect, topographic position, and presence of indicator plant species. Pitfall traps were operated continuously for 180 days from late May to late November, 1983.

Oregon↗