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At least 91 records · Page 5Linked to original sources
USGS2014

Population demographics and life history of the round hickorynut (Obovaria subrotunda) in the Duck River, Tennessee

Population characteristics and life history aspects of healthy mussel populations are poorly understood. The reproductive cycle, age and growth, and population structure of Obovaria subrotunda were examined at four sites in the middle Duck River, Tennessee. Obovaria subrotunda was confirmed to be a bradytictic species, spawning in the late summer and holding glochidia in the gills for 11 mo until the following summer. Fecundity was positively related to mussel length (R 2 = 0.75) and ranged from 7122 to 76,584 glochidia. Fourteen species of fish found in the Duck River, in the families Percidae, Cyprinidae, and Cottidae, were infested with glochidia in the laboratory to examine potential hosts. Juveniles transformed on Etheostoma blennioides (greenside darter), E. obama (spangled darter), E. flabellare (fantail darter), and Cottus carolinae (banded sculpin). Analyses of shell thin-sections indicated that males grew faster and obtained a larger size than females. Individuals live to at least 14 y old. Females became sexually mature at age one. Four sites were quantitatively sampled using a systematic design with three random starts. The observed ratio of adult males to females (0.9∶1) did not differ significantly from 1∶1. Results of the quantitative sampling showed an increase in density compared to earlier studies and a high proportion of 1 to 5 y old O. subrotunda .

Tennessee↗
USGS2014

Historic changes in fish assemblage structure in midwestern nonwadeable rivers

Historical change in fish assemblage structure was evaluated in the mainstems of the Des Moines, Iowa, Cedar, Wapsipinicon, and Maquoketa rivers, in Iowa. Fish occurrence data were compared in each river between historical and recent time periods to characterize temporal changes among 126 species distributions and assess spatiotemporal patterns in faunal similarity. A resampling procedure was used to estimate species occurrences in rivers during each assessment period and changes in species occurrence were summarized. Spatiotemporal shifts in species composition were analyzed at the river and river section scale using cluster analysis, pairwise Jaccard's dissimilarities, and analysis of multivariate beta dispersion. The majority of species exhibited either increases or declines in distribution in all rivers with the exception of several “unknown” or inconclusive trends exhibited by species in the Maquoketa River. Cluster analysis identified temporal patterns of similarity among fish assemblages in the Des Moines, Cedar, and Iowa rivers within the historical and recent assessment period indicating a significant change in species composition. Prominent declines of backwater species with phytophilic spawning strategies contributed to assemblage changes occurring across river systems.

Iowa↗
USGS2014

Model distribution of Silver Chub ( Macrhybopsis storeriana ) in western Lake Erie

Silver Chub ( Macrhybopsis storeriana ) was once a common forage fish in Lake Erie but has declined greatly since the 1950s. Identification of optimal and marginal habitats would help conserve and manage this species. We developed neural networks to use broad-scale habitat variables to predict abundance classes of Silver Chub in western Lake Erie, where its largest remaining population exists. Model performance was good, particularly for predicting locations of habitat with the potential to support the highest and lowest abundances of this species. Highest abundances are expected in waters >5 m deep; water depth and distance to coastal habitats were important model features. These models provide initial tools to help conserve this species, but their resolution can be improved with additional data and consideration of other ecological factors.

American Midland Naturalist↗
USGS2014

Captive propagation, reproductive biology, and early life history of the Diamond Darter ( Crystallaria cincotta )

Reproductive biology and early life history data are critical for the conservation and management of rare fishes. During 2008–2012 a captive propagation study was conducted on the Diamond Darter, Crystallaria cincotta , a rare species with a single extant population in the lower Elk River, West Virginia. Water temperatures during spawning ranged from 11.1–23.3 C. Females and males spawned with quick vibrations, burying eggs in fine sand in relatively swift clean depositional areas. Egg size was 1.8–1.9 mm, and embryos developed within 7 to 11 d. Diamond Darters were 6.7–7.2 mm total length (TL) at hatch. Larvae ranged from 9.0–11.0 mm TL following a 5–10 d period of yolk sac absorption. Larvae had relatively large mouth gapes and teeth and were provided brine shrimp Artemia sp., Ceriodaphnia dubia neonates, marine Brachionus rotifers, and powdered foods (50–400 µm) but did not appear to feed in captivity, except for one observation of larval cannibalization. Larvae survived for a maximum of 10 d. To increase larval survival and reduce the possibility of cannibalism, other alternative food sources are needed during captive propagation.

Tennessee↗
USGS2014

Resource partitioning in two stream salamanders, Dicamptodon tenebrosus and Rhyacotriton cascadae, from the Oregon Cascade Mountains

We investigated the potential for resource partitioning between the Coastal giant salamander ( Dicamptodon tenebrosus ) and the Cascade torrent salamander ( Rhyacotriton cascadae ) by examining their diet and microhabitats in forest streams. Larval D. tenebrosus and R. cascadae fed primarily upon aquatic insect larvae. We found similar foods in larval and adult R. cascadae and combined these results. Dicamptodon larvae consumed ephemeropteran, plecopteran, and trichopteran larvae in about equal amounts whereas R. cascadae ate more trichopteran and less ephemeropteran larvae than D. tenebrosus . Diet of all R. cascadae overlapped more with smaller than larger sized D. tenebrosus larvae. Comparisons of diets with available foods indicated R. cascadae is more selective or more gape-limited in its feeding habits than D. tenebrosus larvae. The two salamanders differed in use of microhabitats in creeks, which may contribute to their diet differences.

Oregon↗
USGS2016

First record of the bigeye shiner ( Notropis boops ) from West Virginia

We report a population of Bigeye Shiner Notropis boops in the South Fork Hughes River drainage of the Little Kanawha River, West Virginia. A total of 27 individuals of N. boops were collected during five sampling efforts from 1999 to 2005. These specimens represent an addition to the state fauna, a distributional record for the Little Kanawha River, and an eastern range extension for this species on the Appalachian Plateau, West Virginia. Notropis boops in the South Fork Hughes River drainage likely represents a native population.

West Virginia↗
USGS2015

Can orchards help connect Mediterranean ecosystems? Animal movement data alter conservation priorities

As natural habitats become fragmented by human activities, animals must increasingly move through human-dominated systems, particularly agricultural landscapes. Mapping areas important for animal movement has therefore become a key part of conservation planning. Models of landscape connectivity are often parameterized using expert opinion and seldom distinguish between the risks and barriers presented by different crop types. Recent research, however, suggests different crop types, such as row crops and orchards, differ in the degree to which they facilitate or impede species movements. Like many mammalian carnivores, bobcats ( Lynx rufus ) are sensitive to fragmentation and loss of connectivity between habitat patches. We investigated how distinguishing between different agricultural land covers might change conclusions about the relative conservation importance of different land uses in a Mediterranean ecosystem. Bobcats moved relatively quickly in row crops but relatively slowly in orchards, at rates similar to those in natural habitats of woodlands and scrub. We found that parameterizing a connectivity model using empirical data on bobcat movements in agricultural lands and other land covers, instead of parameterizing the model using habitat suitability indices based on expert opinion, altered locations of predicted animal movement routes. These results emphasize that differentiating between types of agriculture can alter conservation planning outcomes.

California↗
USGS2015

Raccoon spatial requirements and multi-scale habitat selection within an intensively managed central Appalachian forest

We studied a raccoon ( Procyon lotor ) population within a managed central Appalachian hardwood forest in West Virginia to investigate the effects of intensive forest management on raccoon spatial requirements and habitat selection. Raccoon home-range (95% utilization distribution) and core-area (50% utilization distribution) size differed between sexes with males maintaining larger (2&times;) home ranges and core areas than females. Home-range and core-area size did not differ between seasons for either sex. We used compositional analysis to quantify raccoon selection of six different habitat types at multiple spatial scales. Raccoons selected riparian corridors (riparian management zones [RMZ]) and intact forests (> 70 y old) at the core-area spatial scale. RMZs likely were used by raccoons because they provided abundant denning resources ( i.e ., large-diameter trees) as well as access to water. Habitat composition associated with raccoon foraging locations indicated selection for intact forests, riparian areas, and regenerating harvest (stands <10 y old). Although raccoons were able to utilize multiple habitat types for foraging resources, a selection of intact forest and RMZs at multiple spatial scales indicates the need of mature forest (with large-diameter trees) for this species in managed forests in the central Appalachians.

American Midland Naturalist↗
USGS2015

Status of the Topeka shiner in west-central Iowa

The Topeka shiner Notropis topeka is a federally endangered fish species that is estimated to occupy only 20% of its historic range. In Iowa Topeka shiners have been in decline for decades. Our goal was to determine the present distribution of Topeka shiners in the west-central portion of their range in Iowa and to characterize the extent of its decline. We compared the current distribution to distributions generated from earlier collections. We found Topeka shiners in six of 22 watersheds where they occurred historically. Status of Topeka shiners was judged to be stable in 27% of the watersheds, at risk in 45% of the watersheds, and possibly extirpated in 27% of the watersheds. None were classified as increasing. Based on comparison of the historical distribution with more recent ones, Topeka shiners in west-central Iowa showed a 27% decline a decade ago and currently exhibits a 73% decline in their distribution. The collective evidence from four of five other states in the species&rsquo; range reveals similar declines. This study provides further information on the local distribution and extent of decline for this federally endangered species with a greatly reduced and fragmented overall distribution.

American Midland Naturalist↗
USGS2016

Assessing predation risks for small fish in a large river ecosystem between contrasting habitats and turbidity conditions

This study examined predation risk for juvenile native fish between two riverine shoreline habitats, backwater and debris fan, across three discrete turbidity levels (low, intermediate, high) to understand environmental risks associated with habitat use in a section of the Colorado River in Grand Canyon, AZ. Inferences are particularly important to juvenile native fish, including the federally endangered humpback chub Gila cypha . This species uses a variety of habitats including backwaters which are often considered important rearing areas. Densities of two likely predators, adult rainbow trout Oncorhynchus mykiss and adult humpback chub, were estimated between habitats using binomial mixture models to examine whether higher predator density was associated with patterns of predation risk. Tethering experiments were used to quantify relative predation risk between habitats and turbidity conditions. Under low and intermediate turbidity conditions, debris fan habitat showed higher relative predation risk compared to backwaters. In both habitats the highest predation risk was observed during intermediate turbidity conditions. Density of likely predators did not significantly differ between these habitats. This information can help managers in Grand Canyon weigh flow policy options designed to increase backwater availability or extant turbidity conditions.

Arizona↗
USGS2016

Spatial variation in biofouling of a unionid mussel ( Lampsilis siliquoidea ) across the western basin of Lake Erie

Invasion of North American waters by nonnative Dreissena polymorpha and D. rostriformis bugensis has resulted in declines of the Unionidae family of native North American mussels. Dreissenid mussels biofoul unionid mussels in large numbers and interfere with unionid movement, their acquisition of food, and the native mussels' ability to open and close their shells. Initial expectations for the Great Lakes included extirpation of unionids where they co-occurred with dreissenids, but recently adult and juvenile unionids have been found alive in several apparent refugia. These unionid populations may persist due to reduced dreissenid biofouling in these areas, and/or due to processes that remove biofoulers. For example locations inaccessible to dreissenid veligers may reduce biofouling and habitats with soft substrates may allow unionids to burrow and thus remove dreissenids. We deployed caged unionid mussels ( Lampsilis siliquoidea ) at 36 sites across the western basin of Lake Erie to assess spatial variation in biofouling and to identify other areas that might promote the persistence or recovery of native unionid mussels. Biofouling ranged from 0.03 &ndash; 26.33 g per mussel, reached a maximum in the immediate vicinity of the mouth of the Maumee River, and appeared to primarily consist of dreissenid mussels. A known mussel refugium in the vicinity of a power plant near the mouth of the Maumee actually exhibited very high biofouling rates, suggesting that low dreissenid colonization did not adequately explain unionid survival in this refugium. In contrast, the southern nearshore area of Lake Erie, near another refugium, had very low biofouling. A large stretch of the western basin appeared to have low biofouling rates and muddy substrates, raising the possibility that these open water areas could support remnant and returning populations of unionid mussels. Previous observations of unionid refugia and the occurrence of low biofouling rates in large areas of the western basin of Lake Erie raise the possibility that unionid and dreissenid coexistence may be possible here and elsewhere.

Michigan, Ohio↗
USGS2017

Influence of poisoned prey on foraging behavior of ferruginous hawks

We recorded 19 visits by ferruginous hawks ( Buteo regalis ) over 6 d at two black–tailed prairie dog ( Cynomys ludovicianus ) subcolonies poisoned with the rodenticide Rozol® Prairie Dog Bait (0.005% chlorophacinone active ingredient) and at an adjacent untreated subcolony. Before Rozol® application ferruginous hawks foraged in the untreated and treated subcolonies but after Rozol® application predation by ferruginous hawks was only observed in the treated subcolonies. We suggest that ferruginous hawks' preference for hunting in the treated subcolonies after Rozol® application was influenced by the availability of easy-to-capture prey, presumably due to Rozol® poisoning. The energetically beneficial behavior of favoring substandard prey may increase raptor encounters with rodenticide exposed animals if prey vulnerability has resulted from poisoning.

The American Midland Naturalist↗
USGS2017

Tree species preferences of foraging songbirds during spring migration in floodplain forests of the Upper Mississippi River

Floodplain forest of the Upper Mississippi River is important for songbirds during spring migration. However, the altered hydrology of this system and spread of reed canary grass (Phalaris arundinacea) and emerald ash borer (Agrilus planipennis) threaten tree diversity and long-term sustainability of this forest. We estimated tree preferences of songbirds during spring migration 2010–2013 to help guide management decisions that promote tree diversity and forest sustainability and to evaluate yearly variation in tree selection. We used the point center-quarter method to assess relative availability of tree species and tallied bird foraging observations on tree species as well as recording the phenophase of used trees on five 40 ha plots of contiguous floodplain forest between La Crosse, Wisconsin and New Albin, Iowa, from 15 April through 1 June. We quantified bird preferences by comparing proportional use of tree species by each bird species to estimates of tree species availability for all 4 y and for each year separately. Species that breed locally preferred silver maple (Acer saccharinum), which is dominant in this forest. The common transient migrant species and the suite of 17 transient wood warbler species preferred hackberry (Celtis occidentalis) and oaks (Quercus spp.), which are limited to higher elevations on the floodplain. We observed earlier leaf development the warm springs of 2010 and 2012 and later leaf development the cold springs of 2011 and 2013. Yellow-rumped Warbler (Setophaga coronata), American Redstart (S. ruticilla), Warbling Vireo (Vireo gilvus) and Baltimore Oriole (Icterus galbula), and the suite of transient migrant wood warblers spread their foraging efforts among tree species in colder springs and were more selective in warmer springs. All three of the important tree species are not regenerating well on the UMR and widespread die-off of silver maple is possible in 50 y without large scale management.

Minnesota, Wisconsin↗
USGS2017

Diet composition of age-0 fishes in created habitats of the Lower Missouri River

Channelization of the Missouri River has greatly reduced the availability of shallow water habitats used by many larval and juvenile fishes and contributed to imperilment of floodplain-dependent biota. Creation of small side channels, or chutes, is being used to restore shallow water habitat and reverse negative environmental effects associated with channelization. In the summer of 2012, the U.S. Army Corps of Engineers collected early life stages of fishes from constructed chutes and nearby unrestored shallow habitats at six sites on the Missouri River between Rulo, Nebraska and St. Louis, Missouri. We compared the diets of two abundant species of fishes to test the hypothesis that created shallow chutes provided better foraging habitat for early life stages than nearby unrestored shallow habitats. Graphical analysis of feeding patterns of freshwater drum indicated specialization on chironomid larvae, which were consumed in greater numbers in unrestored mainstem reaches compared to chutes. Hiodon spp. were more generalist feeders with no differences in prey use between habitat types. Significantly greater numbers of individuals with empty stomachs were observed in chute shallow-water habitats, indicating poor foraging habitat. For these two species, constructed chute shallow-water habitat does not appear to provide the hypothesized benefits of higher quality foraging habitat.

Missouri↗
USGS2017

Grassland bird productivity in warm season grass fields in southwest Wisconsin

Surrogate grasslands established through federal set-aside programs, such as U.S. Department of Agriculture's Conservation Reserve Program (CRP), provide important habitat for grassland birds. Warm season grass CRP fields as a group have the potential for providing a continuum of habitat structure for breeding birds, depending on how the fields are managed and their floristic composition. We studied the nesting activity of four obligate grassland bird species, Bobolink ( Dolichonyx oryzivorus ), Eastern Meadowlark ( Sturnella magna ), Grasshopper Sparrow ( Ammodramus savannarum ), and Henslow's Sparrow ( A. henslowii ), in relation to vegetative composition and fire management in warm season CRP fields in southwest Wisconsin during 2009–2011. Intraspecific variation in apparent nest density was related to the number of years since the field was burned. Apparent Grasshopper Sparrow nest density was highest in the breeding season immediately following spring burns, apparent Henslow's Sparrow nest density was highest 1 y post burn, and apparent Bobolink and Eastern Meadowlark nest densities were higher in post fire years one to three. Grasshopper Sparrow nest density was highest on sites with more diverse vegetation, specifically prairie forbs, and on sites with shorter less dense vegetation. Bobolink, Eastern Meadowlark, and Henslow's Sparrow apparent nest densities were higher on sites with deeper litter; litter was the vegetative component that was most affected by spring burns. Overall nest success was 0.487 for Bobolink (22 d nesting period), 0.478 for Eastern Meadowlark (25 d nesting period), 0.507 for Grasshopper Sparrow (22 d nesting period), and 0.151 for Henslow's Sparrow (21 d nesting period). The major nest predators were grassland-associated species: thirteen-lined ground squirrel ( Ictidomys tridecemlineatus ), striped skunk ( Mephitis mephitis ), milk snake ( Lampropeltis triangulum ), American badger ( Taxidea taxus ), and western fox snake ( Elaphe vulpina ). Overall depredation rate was not affected by the number of years since the site had been burned. The diversity of vegetation on warm season CRP fields created by management using fire provides a continuum of structure for obligate grassland birds to use for breeding and habitat for a diversity of nest predators.

Wisconsin↗
USGS2017

Life history attributes of Arizona Grasshopper Sparrow (Ammodramus savannarum ammolegus) and comparisons with other North American subspecies

Ammodramus savannarum ammolegus —commonly referred to as the Arizona Grasshopper Sparrow—occurs in the desert and plains grasslands of southeastern Arizona, southwestern New Mexico, and northern Sonora, Mexico. Although a subspecies of conservation concern, this is the first intensive study of its life history and breeding ecology, providing baseline data and facilitating comparisons with other North American Grasshopper Sparrow subspecies. Specifically, I found A. s. ammolegus males generally weighed less than other subspecies (16.0 ± 0.8 g) but with intermediate exposed culmen length (11.6 ± 0.5 mm) and wing chord length similar to the other two migratory subspecies (62.7 ± 1.5 mm). Territory size for A. s. ammolegus was 0.72 ± 0.37 ha, with some variation between sites and among years, possibly indicating variation in habitat quality across spatial and temporal scales. The return rate for A. s. ammolegus males was 39.2%. Nest initiation for A. s. ammolegus was early to mid-July after the monsoons had begun. Domed nests were constructed on the ground, primarily under native bunch grasses, and frequently with a tunnel extending beyond the nest rim, with nest openings oriented north. Clutch size was 3.97 ± 0.68, with no evidence of Brown-headed Cowbird ( Molothrus ater ) nest parasitism. Extreme climate factors in the arid Southwest may have affected the life history and morphology of A. s. ammolegus as compared to other subspecies, influencing body size and mass, culmen length, breeding phenology, and nest orientation. Other geographic variation occurred in return rates, clutch size, and nest parasitism rates. The baseline data for A. s. ammolegus obtained in this study will inform future taxonomic and ecological studies as well as conservation planning. Comparisons of A. s. ammolegus morphometrics with those of other subspecies will assist field biologists in distinguishing among subspecies where they overlap, especially on wintering grounds.

Arizona↗
USGS2017

Local-scale habitat associations of grassland birds in southwestern Minnesota

Conservation of obligate grassland species requires not only the protection of a sufficiently large area of habitat but also the availability of necessary vegetation characteristics for particular species. As a result land managers must understand which habitat characteristics are important for their target species. To identify the habitat associations of eight species of grassland birds, we conducted bird and vegetation surveys on 66 grassland habitat patches in southwestern Minnesota in 2013 and 2014. Species of interest included sedge wren ( Cistothorus platensis ), Savannah sparrow ( Passerculus sandwichensis ), grasshopper sparrow ( Ammodramus savannarum ), Henslow's sparrow ( Ammodramus henslowii ), dickcissel ( Spiza americana ), bobolink ( Dolichonyx oryzivorus ), and western meadowlark ( Sturnella neglecta ). We calculated correlation coefficients between vegetation variables and species density as measures of linear association. We assessed curvilinear relationships with loess plots. We found grassland birds on 95.5% of surveyed sites, indicating remnant prairie in southwestern Minnesota is used by grassland birds. In general individual species showed different patterns of association and most species were tolerant of a wide variety of habitat conditions. The most consistent pattern was a negative association with both the quantity and proximity of trees. Our findings that individual species have different habitat preferences suggest that prairie resource managers may need to coordinate management efforts in order to create a mosaic of habitat types to support multiple species, though tree control will be an important and ongoing management activity at the individual site level.

Minnesota↗
USGS2017

Evidence for migratory spawning behavior by morphologically distinct Cisco (Coregonus artedi) from a small inland lake

Conservation and management of rare fishes relies on managers having the most informed understanding of the underlying ecology of the species under investigation. Cisco (Coregonus artedi), a species of conservation concern, is a cold-water pelagic fish that is notoriously variable in morphometry and life history. Published reports indicate, at spawning time, Cisco in great lakes may migrate into or through large rivers, whereas those in small lakes move inshore. Nonetheless, during a sampling trip to Follensby Pond, a 393 ha lake in the Adirondack Mountains, New York, we observed gravid Cisco swimming over an outlet sill from a narrow shallow stream and into the lake. We opportunistically dip-netted a small subsample of 11 individuals entering the lake from the stream (three female, eight male) and compared them to fish captured between 2013 and 2015 with gillnets in the lake. Stream-captured Cisco were considerably larger than lake-captured individuals at a given age, had significantly larger asymptotic length, and were present only as mature individuals between age of 3 and age 5. These results could suggest either Cisco are migrating from a nearby lake to spawn in Follensby Pond, or that a distinct morphotype of Cisco from Follensby Pond migrates out to the stream and then back in at spawning time. Our results appear to complement a handful of other cases in which Cisco spawning migrations have been documented and to provide the first evidence for such behavior in a small inland lake.

The American Midland Naturalist↗