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Bumble bees are among the most abundant and important wild pollinators in North America. Spring nest establishment is a brief and vulnerable stage in the colony life cycle that is poorly understood. Bumble bee nesting activity in temperate North America has received little recent attention, and this knowledge gap is a barrier to conservation efforts. The aim of this study was to investigate the habitat use, nesting phenology, and key food plants of spring bumble bee queens. Through 108 nonlethal surveys of bumble bee queens in spring 2018, researchers observed 451 nest seeking and 555 foraging queens of nine species in Ohio, U.S.A. Spring queen activity began in mid-April and peaked in mid-May, although nest seekers were observed into late June. Nest seeking queens favored woody transitional habitats over open habitats. In accordance queen abundance and diversity increased with the proportion of forest in the surrounding landscape. The proportion of row crops and urban areas negatively influenced queen diversity and the number of nest seekers, respectively. Through a literature review, the earliest emergence dates for each species were compared for 12 datasets to establish an order of species emergence in northeastern North America. Forty-seven species of flowering plants were used by foraging queens. Highly visited food plants included both native and nonnatives(*): Lupinus perennis, Malus spp., Taraxacum officinale*, Lonicera spp.*, Lamium purpureum*, Glechoma hederacea*, Trifolium pratense*, and Mertensia virginica. Systematic field surveys are needed by state to document the timing of spring queen emergence and nesting activities to inform conservation efforts.
Wild Lupine (Lupinus perennis) is an indicator of Midwestern U.S.A. oak savannas and the main larval food for endangered Karner Blue butterflies. In the past 100 y, this perennial has declined in distribution and abundance. To determine if this decline was related to population size and/or environmental factors and to better understand patterns of reproduction, we compared frequencies of seed coat colors, seed production variables, and environmental factors among 16 populations ranging in size from 25 to 8300 plants. Seedlings were germinated in the greenhouse to measure early offspring vigor. A seed color/substrate field experiment examined differences in seed removal to look at predation risk. Higher seed production was associated with increased population size, while fewer seeds per fruit were associated with increased bare ground, and higher fruits per stem and seed mass were found as soil pH increased. Although seedling emergence declined with increased bare ground, seedling growth was most correlated with pH and light, but not population size. Small populations had reduced seed color variation. Seed removal rates averaged 65% across all treatments, but dark-colored seeds had higher predation than light-colored seeds, regardless of substrate. Seed removal increased over time and was influenced by vegetative cover and distance to roads and water. Our results suggest managers should minimize the amount of bare ground and strive to maintain population sizes over 500 in order to restore and conserve Lupine populations.
Seed dispersal by animals is an important plant-animal mutualism, but saurochory, the dispersal of seeds by reptiles, is an understudied phenomenon despite its prevalence in many taxa. The effects of seed ingestion by the gopher tortoise (Gopherus polyphemus) were investigated in eight central Florida plant species by comparing germination of ingested seeds to seeds that did not pass through tortoises. Seeds from both treatments were also planted with and without tortoise scat. Both the percentage of seeds germinating and the time to germination were recorded. Ingested seeds from two fleshy-fruited plant species germinated in greater proportions and in less time than control seeds. The presence of scat also increased germination proportion following gut passage and decreased time to germination in both these species. Germination proportions in five dry-fruited native species were either not affected, or lowered, and time to germination was either not affected, or slower. Similarly, the effects of scat had either no effect on germination percentage in these species or caused a decrease, and either had no effect on time to germination or caused an increase. One non-native dry-fruited species was also tested, and although germination percentage following gut passage was unaffected, time to germination decreased. Similarly, while the addition of scat increased germination percentage, there was no effect on time to germination. In summary only seeds from fleshy-fruited plant species were consistently positively impacted by passage through gopher tortoise guts and by gopher tortoise scat.
Habitat destruction and anthropogenic drivers have led to amphibian population declines worldwide, but the conservation status of many species remains in question. This study reports on the distribution of Mudpuppies, Necturus maculosus, in southeast Ohio, where widespread acid mine drainage and other forms of habitat destruction have led to severe declines and extinction in many waterways. Within the last century, however, the region has reforested, and damage to some streams has been mitigated, providing opportunities for Mudpuppy recolonization and population recovery. However, being a relatively secretive species, Mudpuppies require difficult and time intensive field surveys to detect. Therefore, the current distribution and conservation status of Mudpuppies in southeast Ohio is unclear. As a first step in documenting the current distribution and abundance of Mudpuppies in southeast Ohio, we conducted a rapid species assessment using environmental DNA (eDNA) surveys (September–November 2016) at 10 stream sites. We detected Mudpuppies at six of 10 streams using eDNA, including four streams in which they were known to occur from historical records and two streams from which Mudpuppies had not been previously reported. We also collected habitat data at each site, including concentrations of heavy metals and nutrients, physical stream habitat, conductivity, pH, temperature, total dissolved solids, and oxygen levels. Using logistic regression, we found composite Qualitative Habitat Evaluation Index (QHEI) scores were the best predictor of Mudpuppy presence. Our results suggest Mudpuppy eDNA is not easily detected when they are at low density, and animals may need to be within approximately 182 m of sampling points to be detected.
Streams of North America have been degraded by over a century of anthropogenic stressors, including channelization, fragmentation, impoundment, dewatering, and the modification of the natural flow regime. These stressors have contributed to the decline of many freshwater fish species and are particularly detrimental to the pelagic-broadcast spawning reproductive guild of cyprinids. Members of this guild require an unfragmented river section of 458 (±137) river kilometers (rkm) in length to persist. The Plains Minnow is a member of this reproductive guild and is listed within Kansas as a threatened species. Plains Minnow were once common throughout Kansas, but have experienced declines in abundance and distribution. Using historical data and 14 y of new data, we analyzed the proportion of sites occupied by Plains Minnow over time within Kansas as a whole and within specific river basins using parametric linear regression models and nonparametric localized regression models. We found Plains Minnow to be declining within the historical range of the species across the state as a whole and specifically within the Smoky Hill-Saline and Lower Arkansas river basins. We found Plains Minnow distributions to be unchanging within the Kansas-Lower Republican and the Cimarron river basins. Within the Smoky Hill-Saline and the Kansas-Lower Republican river basins, the proportion of sites occupied by Plains Minnow has been at or near zero for the majority of the time period studied. Our findings support previously published studies and contribute to the growing body of evidence that Plains Minnow continue to decline within Kansas. If the species is to recover within the state, anthropogenic stressors will have to be mitigated, and repatriation efforts will need to be conducted.
Habitat use information for many headwater fish species in the southeastern United States is lacking, despite this group's contribution to regional biodiversity. The Tallapoosa Darter Etheostoma tallapoosae is an endemic species to the Tallapoosa River system, found within Georgia and Alabama. In this study collected data from four streams within the upper part of the species' range to provide estimates of habitat use for this rare percid. Our results indicate the Tallapoosa Darter is a microhabitat specialist and typically spawns in areas composed of coarse substrates and characterized by moderate depths (22-31 cm) and current velocities (0.09-0.18 m·s–1). This species also appears to use coarse gravel more than expected for egg-deposition, in relation to other substrate classes. Any future management plans within this river system should feature this endemic given the Tallapoosa Darter is a microhabitat specialist.
Intra- and inter-population comparisons of size at reproduction, clutch size, and egg mass revealed differences between one stream and one lake population of ninespine stickleback (Pungitius pungitius) in Alaska. These results are compared with published data for a second lake population. Ninespine stickleback in the stream appeared to reproduce at a smaller overall average size and to produce greater numbers of smaller eggs per clutch than lake-dwelling ninespine stickleback. This pattern of life history traits is consistent with that reported for populations of the threespine stickleback (Gasterosteus aculeatus) in published studies from Alaska and Central Europe, suggesting stream environments favor a different set of life history tactics than lakes in both species. Further research is needed to test this hypothesis and to elucidate the causal mechanisms.
American martens (Martes americana) in the northern Lower Peninsula of Michigan (NLP) represent a re-introduced and isolated population that is the southern-most distributed marten population in eastern North America. During 2005–2006 we conducted a radiotelemetry and track-survey study of martens in the NLP. We estimated home-range size and patterns of habitat use in order to develop a spatial model to predict distribution of marten habitat. Marten home ranges were comprised of more (>75%) upland deciduous and upland mixed forest compared to the landscape, which included ≤60% of these cover types. Within core areas, martens selected upland conifer stands. Our Penrose habitat model identified <25% of the NLP as primary marten habitat. Further, 70% of marten habitat patches were <1000 ha in size and were isolated by an average of 5.3 km (SE = 2.0). Our marten habitat model identifies focal areas for surveying and monitoring populations and sites for supplementation or re-introduction. Our model also highlights the need for managers to better coordinate active landscape-scale management of wildlife and forests to reduce fragmentation impacts on extant and reintroduced marten populations.
Black bear distribution and dispersal in Mexico are uncertain. Here we document the occurrence of a black bear in the Sierra Gorda Biosphere Reserve in the Mexican State of Queretaro. We assessed its population membership using microsatellites genetic markers and conclude the individual came from the Nuevo Leon population, which is approximately 200 km north of the study area.
Samples of the Skygazer Shiner, Notropis uranoscopus, were taken from the Tallapoosa River from 1988 to 1989. Examination of ovarian condition in female fish showed reproduction occurred from April to August. Clutch size of females varying in length from 40.4– 46.2 mm standard length, and collected in April 1988, ranged from 336 to 582 eggs and was significantly related to female size. Mean female ovum diameter ranged from 0.84 to 0.92 mm and averaged 0.87 mm; there was no significant relationship with female body size. The Skygazer Shiner appears to exhibit an “opportunistic” life-history strategy.
We studied factors associated with survival, sex ratio, and seasonality of the tachinid fly Lespesia archippivora parasitizing monarch butterflies (Danaus plexippus). A total of 424 L. archippivora flies were collected from 124 parasitized monarch larvae in 2016 and 2017. The majority of flies emerged during the monarch's 5th larval instar. Both fly survival and brood size were higher for those emerging during the 5th instar relative to flies emerging during the 4th instar or pupal stage. Brood size ranged from 1 to 10 flies, and the proportion of each brood that successfully pupated to emerge as adults increased with brood size. Adults emerging from larger broods were lighter and smaller, which likely impacts subsequent fecundity and survival. Overall sex ratio was skewed towards males, with 222 male and 129 female adults identified. L. archippivora were recovered from monarchs both early in the season and at the end of the season, with a gap from mid-June to mid-July; a pattern consistent with a bivoltine life cycle.
The fungal pathogen Nosema bombi impacts bumblebee fitness and is a factor in population declines throughout North America. Pesticides are also thought to contribute to declines, because they harm the innate immune system of insects, making them more susceptible to disease. A total of 232 bumblebees were collected at nine different farms across Michigan (U.S.A.), including farms that used pesticides and those that did not, in summer 2017. The bees were identified and tested for Nosema bombi. All bees were found to be free from N. bombi infection, suggesting this microsporidian may not yet have a biologically important impact on bumblebee populations in Michigan.
Ecosystem community structure and function is shaped in part by intra- and inter-specific interactions among plants. Facilitative interactions, wherein one plant benefits another's fitness, can strongly influence plant community dynamics. We investigated the potential of an endemic, perennial bunchgrass, wiregrass (Aristida beyrichiana), to function as a nurse plant for longleaf pine (Pinus palustris) seedlings in fire-maintained pine savannas of the southeastern U.S.A. We documented significantly more pine seedlings growing close to established wiregrass bunchgrasses in a site burned one year prior to sampling. Pine seedlings growing close to wiregrass were also significantly taller than those growing further away. This positive spatial association between wiregrass and pine seedlings suggests that wiregrass facilitates early longleaf pine establishment in flatwoods environments, at least within the first year after fire.
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