Showing papers in "American Midland Naturalist in 2020"
TL;DR: It is found ∼90% of the camera trap events occurred in Aug., Sept., and Oct, which coincides with the maturing of P. strobus cones, suggesting Peromyscus spp.
Abstract: Ecological understanding of many arboreal and semi-arboreal species is limited because of difficulties associated with studying wildlife in canopies. As part of a multi-faceted Pinus strobus canopy research project, we used camera traps located in canopies to examine diel, seasonal, and spatial patterns of Peromyscus spp.'s arboreal habitat use. From 2014 to 2018, we documented 201 events of Peromyscus spp. using the canopy over the course of 8491 camera trap nights, at three separate sites spanning a 57 km north-south transect. We detected Peromyscus spp. at heights up to 24 m, the highest above-ground observation on record, for Peromyscus leucopus (white-footed mouse) or Peromyscus maniculatus (deer mouse), the two species of Peromyscus present within our study area. To determine species-specific canopy use, we live-trapped Peromyscus at the base of each research tree and applied differential markings; right ear tags for P. leucopus and left ear tags for P. maniculatus. Camera trap images revealed both species of Peromyscus climbed with peak activity between 2000 h and 0400 h. We found ∼90% of the camera trap events occurred in Aug., Sept., and Oct. which coincides with the maturing of P. strobus cones, suggesting Peromyscus spp. may seasonally exploit arboreal habitats to forage. Daily and monthly detection probabilities for Peromyscus spp. ranged from 0.15–0.70 and from 0.14–0.91, respectively. The probability of all three cameras failing to detect an individual Peromyscus spp., given it was present in the tree, on any given day or month, ranged from 0.15–0.19 and 0.01–0.06, respectively; indicating our examination of activity patterns was robust. Our observations challenge previous ideas of the arboreal tendencies of Peromyscus spp. and further expand our understanding of the natural history of these species within the arboreal realm.
10 citations
TL;DR: In this paper, the authors quantified the composition of reproductive habitat in lek landscapes across the northern extent of the Lesser Prairie-Chicken range, and examined vegetation characteristics that influence lek attendance.
Abstract: Lesser Prairie-Chicken (Tympanuchus pallidicinctus) populations have declined throughout most of their distribution since the mid-1980s. These declines are largely attributed to loss of habitat through the conversion and expansion of cropland, construction of oil wells and other anthropogenic features on the landscape, and grazing intensification. Changes in habitat availability and quality are seemingly having a disproportionate effect on the reproductive habitat of Lesser Prairie-Chickens, as some populations continue to decline. Nest and brood survival are crucial to population growth of Lesser Prairie-Chickens, with adequate reproductive habitat vital to population persistence. To better understand the influence of reproductive habitat availability on populations, we quantified the composition of reproductive habitat in lek landscapes across the northern extent of the Lesser Prairie-Chicken range. We measured vegetation at six study sites in Kansas and Colorado from 2013–2016. We sought to quantify available nest and brooding habitat adjacent to leks, investigate the relationship between reproductive habitat availability and lek attendance by males at several spatial scales, and examine vegetation characteristics that influence lek attendance. Within 5 km of a lek, 25% (2546/10,320 points) and 26% (2682/10,320 points) of random locations provided nesting and brooding habitat, respectively. Changes to reproductive habitat at both scales affected male attendance at leks. Visual obstruction of vegetation was the main predictor of male lek attendance at both spatial scales and limited the amount of reproductive habitat in lek landscapes. Accordingly, management should increase visual obstruction throughout the Lesser Prairie-Chicken range to increase reproductive success and improve populations to facilitate achieving the conservation goal set by the Western Association of Fish and Wildlife Agencies of a 10 y average Lesser Prairie-Chicken population of 67,000 birds.
9 citations
TL;DR: More interventions are likely required for the restoration and reference plant communities to converge in arid environments, and it is suggested considering multiple seeding treatments that will maximize the potential for ideal germination conditions and additional local interventions that may help accumulate litter and protect seeds.
Abstract: Recovery of degraded lands in arid environments is especially challenging due to difficulty of matching ideal conditions to seed germination requirements and reduced native soil seed banks. Restoration practitioners try to overcome these challenges through seeding and site preparation treatments. In the McDowell Sonoran Preserve, Scottsdale, Arizona, the focus for restoring old roads was on seeding, cactus transplants, and soil treatments (either ripping or adding soil from nearby construction areas). Here we evaluated the success of these restoration sites 5–8 y after project completion. We compared vegetation and ground cover on eight roads that received a combination of these restoration treatments with adjacent reference areas. Plant cover was similar between the restoration and reference plots, but plant composition was different. The restoration plots contained more cacti due to cactus transplants, whereas the reference areas contained more shrub cover. The number of native plant species was greater in the reference areas than in the restoration plots. Seeding treatment had little effect, with only five of 11 seeded species appearing in plots, and only one species, Bouteloua aristidoides, appeared in both treatments that included seeding. Although cacti may have contributed to overall plant cover, they did not appear to aid establishment of other plants. Our findings suggest more interventions are likely required for the restoration and reference plant communities to converge in arid environments. We suggest considering multiple seeding treatments that will maximize the potential for ideal germination conditions and additional local interventions that may help accumulate litter and protect seeds.
7 citations
TL;DR: This research examined how interspecific variation in activity level and response to predation risk, corresponds to the distributions of tadpole species along the hydroperiod gradient, and highlighted this tradeoff can have consequences on the life histories of multiple species.
Abstract: Increasing activity levels permit greater food intake for use towards growth and reproduction, consequently increasing predation risk via increased detection. Larval anurans are models to examine activity level-predation risk tradeoffs, as they occupy a variety of lentic habitats that impose constraints on the distribution and abundance of species. Ephemeral ponds have a low abundance and diversity of predators and as a result tadpole species tend to have high foraging rates for rapid development. Permanent ponds generally possess a greater diversity and abundance of predators and tadpoles inhabiting these locations tend to have low activity rates or chemical defenses to minimize predation risk. The objective of this research was to examine how interspecific variation in activity level and response to predation risk, corresponds to the distributions of tadpole species along the hydroperiod gradient. Furthermore, we examined the intraspecific variation in activity level among the species. We conducted a series of laboratory experiments in which we quantified baseline activity patterns and the change in activity after the addition of a predator or exposure to alarm cues, for 12 species of larval anurans native to East Texas. Species that maintained a high activity level generally occupied ephemeral ponds and species that maintained low activity levels generally occupied permanent ponds. Only one species (Gastrophryne carolinensis) decreased their activity level in the presence of predator cues or conspecific alarm cues. These results highlight this tradeoff can have consequences on the life histories of multiple species, providing insight into how it affects the organization of ecological communities.
6 citations
TL;DR: In this article, the authors examined the interplay of soil texture and vegetation structure in determining site occupancy of the southeastern pocket gopher (Geomys pinetis), a species of conservation concern throughout its range.
Abstract: Pocket gophers (Geomyidae) require soils amenable to burrowing and vegetation communities that provide adequate foods. We examined the interplay of soil texture and vegetation structure in determining site occupancy of the southeastern pocket gopher (Geomys pinetis), a species of conservation concern throughout its range. Using a case-control sampling design, we compared vegetation structure and soil texture between occupied and unoccupied sites in southeastern Alabama. All occupied sites had soil clay content ≤8.05% at 0–20 cm depth. In logistic regression modeling, clay content had overwhelming support as the most important single habitat variable distinguishing occupied from unoccupied sites. Based on soil results, we focused our examination of vegetation structure on the subset of our sites with <10% clay at 0–20 cm depth. Relative odds of occupancy were highest at intermediate levels of canopy cover; however, canopy cover at occupied sites ranged widely. Compared to unoccupied sites, occupied sites contained less midstory cover and greater ground cover of graminoids and shrubs. Our results demonstrate that although vegetation structure is important in determining site suitability, soil texture may be an overriding constraint limiting potential habitat for this species. Conservation actions for southeastern pocket gophers such as habitat restoration and population translocations should ensure that target sites have suitable low-clay soils.
6 citations
TL;DR: In this article, the importance of fire before Euro-American settlement on three landscapes, two within the Prairie Peninsula and one outside the region, were used to calculate an index, pyrophilic percentage.
Abstract: Bearing-tree data were used to calculate an index, pyrophilic percentage, depicting the importance of fire before Euro-American settlement on three landscapes, two within the Prairie Peninsula and one outside the region. Based on functional traits, bearing trees were classified as either pyrophilic or pyrophobic, applied to Public Land Survey points, and the pyrophilic percentage was calculated for each point. Kriging was applied to this point database to create a continuous surface of pyrophilic percentages. Regression analysis was used to relate this surface to environmental factors. Regression models created separately for each study area explained 38 to 53% of the variation in pyrophilic percentage. A positive association between pyrophilic percentage and distance to water and summer potential evapotranspiration was consistent across all study sites. The consistently high values and spatial patterns of pyrophilic percentage revealed fire-dominated landscapes interspersed with patches of pyrophobic vegetation. The restriction of pyrophobic areas to the leeside (east) of waterbodies indicated these served as firebreaks in a fire-swept landscape. Lake Michigan must have had a profound effect on pre- Euro-American settlement fire environments, serving as a massive physical firebreak while casting a moist maritime climate eastward. In southern and southwestern Illinois, the Mississippi River and associated tributaries along with an increase in topographic complexity also served as firebreaks, with pyrophobic forests restricted to riparian zones which progressively graded to pyrophilic vegetation on surrounding uplands. Our analysis expands the use of Public Land Survey data by converting bearing trees into a meaningful fire ecology index. While much of the landscape included in our study area is now in agriculture or urbanized, pyrophilic percentage maps can help guide land managers in the application of fire for restoration, conservation, and forestry purposes.
4 citations
TL;DR: The authors used a citizen science-based methodology to survey 92 municipalities in southeastern Wisconsin in areas with varying degrees of urbanization to establish baseline data for this species that can then be compared to future counts.
Abstract: Limited survey data and numerous anecdotal accounts indicate the Common Nighthawk (Chordeiles minor) is experiencing population declines not only in Wisconsin, U.S.A., but across large parts of their range in North America. However, it is possible estimates from current avian monitoring efforts are not representative, because surveys are not necessarily conducted at dusk when C. minor are most active, nor do they specifically target urban areas where a portion of the C. minor population are known to nest on flat graveled rooftops. Therefore, urban crepuscular monitoring protocols are needed to address these issues, enhance current monitoring efforts, and gain a better understanding of C. minor demographics. In this study we used a citizen science-based methodology to survey 92 municipalities in southeastern Wisconsin in areas with varying degrees of urbanization to establish baseline data for this species that can then be compared to future counts. We investigated the influence of a range of environmental and ecological factors, as well as landscape features and land cover types in relation to C. minor occurrence. C. minor detection was positively correlated with Chimney Swift (Chaetura pelagica) counts, the number and area (m2) of flat graveled rooftops, and heavily developed land cover types. The surveys also revealed a negative correlation between agricultural land cover and C. minor occurrence. Overall, the use of citizen science to establish a baseline for C. minor was successful and may be adapted and applied to other crepuscular bird species at a broader geographic scale of similar landscape type.
4 citations
TL;DR: In this article, a non-metric multidimensional scaling (NMDS) analysis identified high temporal variation as assemblage structure differed among decades, indicating significant differences by river location upstream, urban, and downstream.
Abstract: We tested macroinvertebrate assemblages collected from 1979–2015 for temporal variation in structure and for impacts of the Clean Water Act of 1974. Collections were at ten sites on the mainstem of the West Fork White River. We used family-level taxonomy for macroinvertebrates that resulted in 77 families and 92,477 individuals. Macroinvertebrate families were further classified by trophic and tolerance traits and tested for temporal variation. We defined river reaches as upstream, urban, and downstream of Muncie, Indiana for analyses. Taxonomic richness increased over the study. A nonmetric multidimensional scaling (NMDS) analysis identified high temporal variation as assemblage structure differed among decades. Spatial analyses using NMDS indicated significant differences by river location upstream, urban, and downstream. NMDS and Analysis of Similarities (ANOSIM) by trophic relationship and tolerance values did not result in significant temporal or spatial patterns. Our results show the macroinvertebrate assemblages of the West Fork White River improved, likely due to implementation of the Clean Water Act.
4 citations
TL;DR: In 2015, a new species of Corbicula, known as Form D, was discovered in the Illinois River, at Marseilles, Illinois, and was later reported from the Ohio River.
Abstract: The genus Corbicula contains one of the most common and successful aquatic invasive species to North America. Prior to 2015 two predominant species of Corbicula were known from the United States—C. fluminea and C. largillierti, referred to as Forms A and B, respectively. Form A has spread throughout most of the U.S., while Form B is mainly contained in the Midwest and southern U.S. In 2015 a novel Corbicula, known as Form D, was discovered in the Illinois River, at Marseilles, Illinois, and was later reported from the Ohio River. Our primary objective for this study was to report additional records of Form D, with a focus on the upper Illinois River watershed. Surveys during summer 2017 verified the presence of Form D in the Tennessee and Mississippi rivers, as well as multiple new locations in the Des Plaines and Illinois rivers, where all three Corbicula forms co-exist.
4 citations
TL;DR: In this article, the authors present the diversity, habitats, biogeography, and conservation status of Carex in Jackson County, Alabama, and document 90 Carex taxa from Jackson County by voucher specimens deposited in multiple herbaria.
Abstract: Jackson County is the northeasternmost county of Alabama, U.S.A., and falls entirely in the southern portion of the Appalachian Plateaus physiographic province. Based on multiple years of fieldwork, herbarium work, and review of online (digitized) specimens, this study presents the diversity, habitats, biogeography, and conservation status of Carex in Jackson County. We document 90 Carex taxa from Jackson County by voucher specimens deposited in multiple herbaria. This value exceeds the number of taxa known from other, similar-sized regions in the southern part of the Appalachian Plateaus. Carex albicans var. emmonsii is a new state record and is known in Alabama only from Jackson County. We encountered high numbers of misidentifications among specimens collected prior to this study and exclude nine taxa previously reported from Jackson County that are based on misidentifications. Carex plants grow in a great number of habitats in Jackson County, with two hosting the greatest number of taxa: mature, wet-mesic, deciduous, floodplain forests on clays and clay loams; and mature, mesic, calcium-rich, deciduous, upland forests on loams. Jackson County is a nexus for both southeastern endemics and taxa occurring at or near their southern limits. Thirteen of the Carex taxa are rare in Alabama and likely of conservation concern in the state. This study contributes fundamental knowledge that makes sedge diversity, ecology, geography, and conservation better known, and is especially important for revealing a significant center of Carex diversity in North America.
3 citations
TL;DR: In this paper, the authors examined community scientist observations of moose collected by the Wisconsin Department of Natural Resources from 1991-2017 to determine the trends of the moose occurrence in Wisconsin and the relationship to potential drivers.
Abstract: Wildlife conservation and management requires an understanding of patterns and changes in the populations and distributions of wildlife. Moose (Alces alces) population trends vary within regions of North America, such as in the upper Midwest region of the United States where sub-populations are declining in Minnesota, but are stable or increasing in Michigan. The population and distribution of moose in Wisconsin, which shares a border with Minnesota and Michigan, is unknown. We examined community scientist observations of moose collected by the Wisconsin Department of Natural Resources from 1991–2017 to determine the trends of moose occurrence in Wisconsin and the relationship to potential drivers. We used a binomial generalized linear mixed model in a Bayesian framework to understand how variables affect county-level occurrence of moose. We found moose occurrence was greater in counties closer to Minnesota and Michigan, but the effect of distance to Minnesota on moose occurrence has decreased over time. We also found counties with higher habitat suitability and proximity to Michigan are more likely to have a moose occurrence than those with low habitat suitability. This study offers insight for moose populations at the southern fringe of their circumpolar distribution and a foundation for understanding the moose population in Wisconsin and the upper Midwest.
TL;DR: Though highly variable from year to year, the overall prevalence of parasitism was low and bot flies do not appear to be a widespread parasitic burden to Allegheny woodrats in Virginia.
Abstract: The Allegheny woodrat (Neotoma magister) is a species of high conservation concern and relatively well-studied with respect to habitat use/associations, food habits, conservation genetics, and population trends. However, with the exception of raccoon roundworm (Baylisascaris procyonis) occurrence and etiology in woodrats, most disease and parasite ecology aspects for the woodrat are unknown. Herein, we examined the prevalence of bot flies (Cuterebra) over nearly three decades of woodrat surveys (1990–2018) in the central Appalachian Mountains of western Virginia. We use genetic analyses to identify recent bot fly specimen collections from a woodrat captured in 2017. Though highly variable from year to year, the overall prevalence of parasitism was low (typically < 4% of captures). As such, bot flies do not appear to be a widespread parasitic burden to Allegheny woodrats in Virginia. Genetic analysis of four collected bot fly larvae was inconclusive, as the genetic signature of these woodrat bots did not match any of the six bot species known to parasitize rodents and lagomorphs in the eastern United States. Further collections and genetic analyses will be needed to determine if the genetic database is incomplete or incorrect, or if our find is a new species of bot fly not yet taxonomically recognized.
TL;DR: Whether the three weevil species are more flexible in their host preferences than previously known is tested, using adult weevils and substituting Ci.
Abstract: Nonnative invasive species are a threat to biodiversity worldwide. One common method for invasive species management is biological control (biocontrol). However, biocontrol can have unanticipated nontarget effects on native species. Cirsium pitcheri (Pitcher's thistle) is a federally threatened plant endemic to the Great Lakes dunes. Unfortunately, a formerly-recommended biocontrol weevil (Larinus carlinae, used in an effort to control Cirsium arvense and previously referred to as Larinus planus within the biocontrol literature) impacts Ci. pitcheri seed production in large portions of its range and is contributing to population declines. Two congeneric species of weevil (L. minutus and L. obtusus), introduced to control spotted knapweed (Centaurea stoebe subsp. micranthos), may pose a similar risk of nontarget interactions with Ci. pitcheri. All three weevil species have been known to use both Cirsium and Centaurea species in their European range. To understand weevil preferences, we performed a set of choice and nonchoice trials under laboratory conditions in order to test whether the three weevil species are more flexible in their host preferences than previously known, using adult weevils and substituting Ci. arvense for Ci. pitcheri in the case of L. carlinae, due to limited availability of the latter, endangered thistle. All three weevil species spent more time feeding on their intended/known hosts but also fed on the nontarget species, and in some cases the differences were not significant. All three weevil species always oviposited on their known hosts, with no ovipositions on the other test species. Based on our results, neither L. minutus nor L. obtusus is likely to be a major threat to Ci. pitcheri, and L. carlinae is unlikely to use Ce. stoebe as a host.
TL;DR: The authors examined the effects of restoration of a montane longleaf pine forest in Paulding County, Georgia, U.S.A. on tree canopy, groundcover and bird communities over a decade.
Abstract: Fire suppression and hardwood encroachment are two of the most significant threats to the imperiled, fire-dependent montane longleaf pine ecosystem. We examined the effects of restoration of a montane longleaf pine forest in Paulding County, Georgia, U.S.A. on tree canopy, groundcover and bird communities over a decade. The restoration included a program of prescribed fire and selective thinning to reduce tree canopy density and reduce or remove offsite species. Several conservation goals were met including the recovery of characteristic tree composition and groundcover. Birds responded with sharp increases in richness and abundance, with many shrub and woodland dependent species of high conservation value detected post-restoration. Our research demonstrates these sites are easily restorable and such projects will likely yield significant gains for conservation.
TL;DR: Monitoring of radio-collared bobcats in south-central Indiana from 1998 to 2006 found vehicle collisions were the largest source of mortality, followed by illegal shootings, and higher values of habitat heterogeneity within home ranges were associated with lower risk of mortality.
Abstract: Bobcat (Lynx rufus) populations have increased in the midwestern U.S. since the 1980s after substantial declines and local extirpations into the mid-1900s. We monitored 38 radio-collared bobcats (25 males, 13 females) from 1998 to 2006 in a recovering population in south-central Indiana to investigate survival and mortality causes. Annual survival was high (Ŝ = 0.80, 95% CI = 0.71–0.89), comparable to results from other studies of bobcats in unexploited populations and higher than in harvested populations. Of 17 known deaths, vehicle collisions were the largest source of mortality (n = 9; 53%), followed by illegal shootings (n = 3; 18%). Higher values of habitat heterogeneity within home ranges were associated with lower risk of mortality. Estimates of survival and mortality sources in recovering populations provide an important context to compare management strategies to improve bobcat conservation.
TL;DR: Mozingo Lake was sampled monthly for 4 y following its impoundment in order to further understand trophic upsurges and to refine the classic model of up-surges as mentioned in this paper.
Abstract: Mozingo Lake was sampled monthly for 4 y following its impoundment in order to further understand trophic upsurges and to refine the classic model of upsurges. Upsurge 1 occurred in Month 8, when lake area increased by 184% and inundated only floodplain with comparable coverages of forest, cropland, and grassland (30%–33% each). At this time nitrate increased dramatically and was related to both precipitation and lake area increase, likely due to ammonia-based fertilizers from the flooded cropland. Phytoplankton biovolume remained low, however, likely due to the abundance of Daphnia and other zooplankton grazers. After recovery, the lake expanded dramatically again in Month 21 (Upsurge 2); lake area increased by 36%, but this expansion flooded land with less floodplain (23%) and with different proportions of land use (45% grassland, 31% forest, 14% cropland). Upsurge 2 experienced initial increases in nitrate and zooplankton, but these were minor compared to Upsurge 1, and phytoplankton remained low. These initial responses were followed by substantial increases in phosphate, which related to lake area increase; cyanobacteria biovolume expanded, but zooplankton abundance declined. Therefore the two upsurges were driven by different factors: nitrate in Upsurge 1, but phosphate in Upsurge 2. These drivers, in turn, may reflect differences in the newly-flooded land, including differences in land use and in landscape position (i.e., slope). In addition to seasonal succession, the phytoplankton of Mozingo Lake exhibited longer-term primary succession that related first to nitrate, then to grazing, then to multiple factors, suggesting increases in food web complexity. In contrast to the classic model of upsurges, the biotic responses in Mozingo Lake were quite transitory, and the nature of the upsurges varied with the characteristics of the newly-inundated land. Therefore, it appears that trophic upsurge is more variable than the classic model suggests.
TL;DR: A tooth of Phoebodus cf. sophiae (Chondrichthyes, Elasmobranchii) was recovered from the Middle Devonian, Early Givetian, Rockport Quarry Limestone Formation in Alpena, Michigan.
Abstract: A tooth of Phoebodus cf. P. sophiae (Chondrichthyes, Elasmobranchii) was recovered from the Middle Devonian, Early Givetian, Rockport Quarry Limestone Formation in Alpena, Michigan. It is the first known record of the taxon in Michigan and the third known locality from North America. It is the oldest known record in North America, and possibly worldwide, and may extend the known temporal range of the genus. Previous known records for P. sophiae have been confined to the middle Givetian Polygnathus varcus conodont zone, and the taxon was thought to be a possible index fossil for the middle Givetian. The present record extends the taxon to the early Givetian P. hemiansatus conodont zone and, thus, complicates the use of P. sophiae as a proxy index fossil for the P. varcus zone.
TL;DR: In this article, the authors investigated select intrinsic properties of individuals and reproductive output of breeding yearling females and their mates for potential differences in the ecology of urban vs. rural birds in Wisconsin, 1980-2017.
Abstract: Cooper's Hawks (Accipiter cooperii) nest commonly in various habitats throughout North America, but there are few comparative studies of the ecology of urban vs. rural nesting birds, especially regarding 1 y olds whose inexperience is purported to place them under different selective pressures than more commonly nesting hawks ≥ 2 y of age. Notably, selective pressures of cities have prompted recent changes in the life histories and phenotypes of urban birds, and some of these pressures may be age dependent. We investigated select intrinsic properties of individuals and reproductive output of breeding yearling females and their mates for potential differences in the ecology of urban vs. rural birds in Wisconsin, 1980–2017. We found no differences in mean body mass of yearling females, their male mates, nesting phenology, nor in average clutch or brood counts in urban vs. rural Cooper's Hawks. Excluding one instance, yearling females were mated to older males, ≥ 2 y of age, and within 33 pairs birds mated by like sizes (small/small, etc.). Sums of masses for paired birds were not correlated with their brood sizes, in contrast to our earlier findings on the same study areas where brood size was positively and significantly correlated with summed masses of paired birds ≥ 2 y old who also mated by similar size. We call for more comparative studies of Cooper's Hawks in cities < 100,000 people as studied herein, as most research on urban nesting Cooper's Hawks stem from large, metropolitan cities with about 1 million people, which are less prevalent than smaller cities as we investigated. Indeed, there is growing evidence worldwide that the types and strength of selective pressures on urban wildlife is greater in larger cities, yet less is known about small cities.
TL;DR: Species-interaction network analysis was used to compare two trophic networks; pre- and post-abandonment of Seahorse Key waterbirds and several species of colonial nesting birds were identified as holding important positions within the network for resource transfer from marine and intertidal environments to terrestrial Trophic guilds, particularly to the snakes.
Abstract: In 2015 the entire breeding colony of nesting waterbirds on Seahorse Key (Florida, U.S.A.) unexpectedly abandoned the island and have not returned. These birds have a unique trophic relationship with a sympatric cottonmouth snake (Agkistrodon conanti) population, as well as potentially important positions within the entire insular food web. Species-interaction network analysis was used to compare two trophic networks; pre- and post-abandonment. Trophic data were used to create a weighted adjacency matrix for each network and the resulting network metrics were compared using the network analysis software package UCINET and visualized using NetDraw. Results for the pre-abandonment network indicated a large, complex, diffuse network with low centrality and seven sub-networks. Several species of colonial nesting birds were identified as holding important positions within the network for resource transfer from marine and intertidal environments to terrestrial trophic guilds, particularly to the snakes. Post-abandonment analysis showed the network significantly fractured with the terrestrial trophic guild that includes the snakes being smaller, more isolated and potentially less stable.
TL;DR: In this paper, the authors used empirical field descriptions, complemented by published floras and the resources at centers for species conservation, to explore macro-ecological patterns in interactions between plants and ants.
Abstract: Diagnosing the variability in prospective inter-specific interactions informs both our understanding of particular species as well as how the ecological complex of which they can be a part are altered by their presence. This study uses empirical field descriptions, complemented by published floras and the resources at centers for species conservation, to explore macro-ecological patterns in interactions between plants and ants. I describe on-plant foraging by ants on 70 plant species (11 families, 29 genera) in the Sonoran Desert region, highlighting particular combinations of plant species, ontogenetic stages, and season where forager visitation is disproportionately high or low. Through my plant-ant association surveys, I find species-specific descriptions of on-plant foraging: (1) are qualitatively similar among sites (an arboretum and a wilder location), (2) can predict the activities of ground foraging ants at the patch scale (plant neighborhoods of 12 m2), (3) show plant community types within the warm North American deserts have diverging likelihoods of on-plant foraging, and (4) brief inspections can describe among-plant variation in likelihoods of visitation by ants as well as herbivores that can be deterred by ants.
TL;DR: High survival for calves likely due to productive habitats, an ecosystem-specific predator guild, and high alternative prey is document.
Abstract: We conducted a 2 y study of survival and cause-specific mortality of elk (Cervus elaphus) calves to determine the current status of elk occupying the southwestern region of the Black Hills National Forest, South Dakota and eastern Wyoming. We captured and fit 71 calves ≤10 d of age with expandable radiocollars during summer 2012 (n = 37) and 2013 (n = 34). We used known-fate analysis in Program MARK to estimate summer (15 May–25 Sep.) and annual (12 mo) survival for elk calves. The top model for summer survival was {S1–2wk,3–20wk} indicating mortality during 1–2 wk of age and 3–20 wk of age best explained survival; overall probability of surviving 20 wk was 0.79 (95% CI = 0.68–0.88). For annual (12 mo) survival, model {Sbirthweight} had the lowest AICc value indicating birth weight of elk calves best explained survival as heavier born calves had a higher probability of survival. The overall probability a calf survived to 12 mo of age was 0.75 (95% CI = 0.61–0.84). Cougar (Puma concolor) predation accounted for 81% of mortalities; remaining mortalities were from starvation (6.3%, n = 1) and unknown causes (6.3%, n = 1). Our results document high survival for calves likely due to productive habitats, an ecosystem-specific predator guild, and high alternative prey.
TL;DR: Northern Harriers in western Indiana exhibited great diet flexibility, which likely reflects local prey populations and constraints of life in intensive agroecosystems.
Abstract: We assessed geographic and temporal variation in diets of wintering Northern Harriers (Circus hudsonius) in western Indiana, U.S.A., using multivariate regression on counts of prey from pellets collected at communal roosts. Because there is no uniform method for determining the minimum number of individuals (MNI) contained in a pellet, we also assessed whether application of four different counting methods influenced our conclusions. We collected 821 Northern Harrier pellets from four roosts in 2018 and 2019. Pellet contents differed between years, months, and roost sites. Voles (Microtus spp.) were the most commonly occurring prey group at all roosts and in both years (range: 45–73%), but were encountered 35% less frequently than reported on average by other studies in the midwestern U.S.A. Accordingly, other small mammal prey groups became more important dietary components than reported by most other midwestern studies, including mice (Peromyscus; 5–16%), western harvest mice (Reithrodontomys megalotis; 4–14%), and northern short-tailed shrews (Blarina brevicauda; 8–18%). The four methods of counting MNI produced no discernible effects on our conclusions concerning pellet contents between months or roosts. Northern Harriers in western Indiana exhibited great diet flexibility, which likely reflects local prey populations and constraints of life in intensive agroecosystems.
TL;DR: The Common Black Hawk (Buteogallus anthracinus) has been known since the 1970s to nest as far north as western Texas, but few breeding records exist for the adjacent area of northcentral Mexico as discussed by the authors.
Abstract: The Common Black Hawk (Buteogallus anthracinus), a widespread neotropical raptor, has been known since the 1970s to nest as far north as western Texas, but few breeding records exist for the adjacent area of northcentral Mexico. In 2015 we located two active nest sites within the Maderas del Carmen Flora and Fauna Protection Area at northwestern Coahuila. The nest sites were in Pecan (Carya illinoiensis) and Arizona Pine (Pinus arizonica) trees, both near natural permanent water sources. Our recent nest site records along with others in eastern Coahuila suggest the existence of a corridor connecting Texas and Nuevo Leon populations, highlighting the importance of transboundary natural protected areas for species conservation.
TL;DR: In this paper, a logistic regression generalized linear model was used to classify 40 sugar maple-basswood sites in the Chippewa National Forest of Northern Minnesota as wormed or unwormed (i.e., presence or relative absence of earthworms, respectively).
Abstract: Over the last century, nonnative earthworms have invaded forests of the Great Lakes region of North America. Although a growing body of scientific research has documented short-term changes associated with invasive earthworms, there is little research describing the effects of invasive earthworms over multiple decades. To investigate the long-term effects of invasive earthworms on forests, sites sampled in the past need to be classified as wormed or unwormed when originally sampled. However, this is often difficult to accomplish because field methods for sampling earthworms have only recently been developed, and the few historical permanent sites available for resampling largely do not have past information about earthworm presence or absence. Although historic sites lack data on invasive earthworm presence, many of these sites do have information about soil horizon thickness. Therefore, soil horizons can potentially be used as an indicator of the presence or absence of invasive earthworms. In this paper we developed a logistic regression generalized linear model to classify 40 sugar maple-basswood sites in the Chippewa National Forest of Northern Minnesota as wormed or unwormed (i.e., presence or relative absence of earthworms, respectively). A model using the thickness of the O horizon as a predictor variable correctly classified 93% of sites resampled in 2017 as wormed or unwormed. This result suggests we can predict which sugar maple-basswood stands in the Chippewa National Forest were wormed in the past. By comparing historic conditions to those present today, we can then analyze the long-term effects of invasive earthworms.
TL;DR: This migration ‘rush’, along with the ability to move at cold temperatures and to vary timing of migrations likely helps montane R. pretiosa deal with colder and more variable spring conditions than lowland populations.
Abstract: Relatively few North American anurans overwinter in water and information is sparse on their movement from overwintering habitat to breeding sites. Oregon spotted frogs (Rana pretiosa) breed explosively in early spring and often overwinter submerged at sites that are distanced from breeding habitats. In montane parts of their range, wintering and breeding habitats can remain frozen for months. We investigated timing, duration, and potential cues for R. pretiosa migrations from a wintering lake near the Cascade Mountains in central Oregon, U.S.A. First and median migrant males moved slightly earlier than females. Onset of migration was as early as February 12 (males) and as late as April 4 (females) in years of mild and extended winters, respectively. Frogs were active at water temperatures below those associated with early breeding activities in one lowland R. pretiosa population. Higher proportions of frogs migrated before ice-out in years of prolonged winter conditions. Migrations were temporally compressed in years of later movement. This migration ‘rush’, along with the ability to move at cold temperatures and to vary timing of migrations likely helps montane R. pretiosa deal with colder and more variable spring conditions than lowland populations.
TL;DR: Extensive hybridization and introgression in the Fox River drainage may have been facilitated by the close phylogenetic relationship of Longnose and Shortnose Gar, the much greater abundance of LongNose relative to Shortn Nose Gar in theFox River drainage, the apparent relatively recent colonization of the FoxRiver drainage by the Shortnosed Gar, and the substantial modification and loss of gar spawning habitat in the fox River drainage caused by dams and artificial water level regulation.
Abstract: Hybridization among gar species (Pisces: Family Lepisosteidae) has only recently been documented, and relatively few occurrences have been reported. In the Fox River drainage of the Lake Michigan Basin in Wisconsin, apparent hybrids and introgressed individuals (hereafter “hybrids”) of Longnose Gar (Lepisosteus osseus) and Shortnose Gar (L. platostomus) were widespread and numerous, constituting about 44% of the total gar population. Presumed hybrids could be readily distinguished by either their intermediate ratio of snout length to snout width or a low ratio, characteristic of Shortnose Gar, coupled with the presence of conspicuous spots on the top of the snout, an occasional Longnose Gar characteristic. Presumed hybrids had genetic matrilines (cytochrome b) of either Shortnose or Longnose Gar. Apparent hybrids occur commonly throughout the Fox River drainage, including the upper and lower Fox River, its major tributary the Wolf River, the riverine lakes Poygan, Winneconne, Butte des Morts, Winnebago, and Little Butte des Morts, and Green Bay, Lake Michigan, near the mouth of the lower Fox River. Evidence exists for possible hybrids in the adjacent Mississippi River basin and the Missouri River basin, but they appear to be less common and more localized. Extensive hybridization and introgression in the Fox River drainage may have been facilitated by the close phylogenetic relationship of Longnose and Shortnose Gar, the much greater abundance of Longnose relative to Shortnose Gar in the Fox River drainage, the apparent relatively recent colonization of the Fox River drainage by the Shortnose Gar, and the substantial modification and loss of gar spawning habitat in the Fox River drainage caused by dams and artificial water level regulation.
TL;DR: In this paper, a case study in a private property in Newaygo County, Michigan for which prescribed fire had been implemented every 2 y from 2007 through 2011 to promote recruitment of key understory vegetation, but there had been no follow-up recovery assessment.
Abstract: Oak-pine barrens ecosystems provide critical habitat for the federally endangered Karner blue butterfly (Lycaeides melissa samuelis). Wild lupine (Lupinus perennis), an herbaceous perennial in this ecosystem is the only food source for the butterfly's larvae. The range and quality of these ecosystems have declined significantly. Restoration in private lands can be key to expanding these habitats, but often there is limited or no follow-up to assess the recovery of the site following restoration treatments. We conducted a case study in a private property in Newaygo County, Michigan for which prescribed fire had been implemented every 2 y from 2007 through 2011 to promote recruitment of key understory vegetation, but there had been no follow-up recovery assessment. The burn treatment consisted of a section that was not burned, one that was burned twice, and one that was burned three times. We collected data on vegetation groups and site related factors along this fire gradient to examine differences as a function of fire frequency, as well as delineate factors driving patterns of understory plant recruitment. Results show little tree recruitment from seedlings, but high densities of tree saplings recruited via resprouting. Estimated cover of lupine was low across all treatments, whereas Pennsylvania sedge (Carex pensylvanica Lam,) was highest among species in both cover and biomass. Lupine exhibited a negative relationship with Pennsylvania sedge, litter, and sprouted tree saplings, but a positive relationship with moss cover. We make recommendations for additional restoration interventions and highlight the need for continued support of private landowners as they engage in conservation of imperiled species.
TL;DR: Re-assess seed germinability of Synthyris bullii seeds collected from 2008 to 2011 across its range found regardless of seed age, locality, and maternal environment, seeds are still viable.
Abstract: Synthyris bullii (Plantaginaceae; Besseya bullii; kittentails) is a rare endemic of the Midwestern U.S.A. Although seed germination studies have been conducted for this species, limited information is available regarding seed viability after prolonged seed storage. The main goal of this study was to re-assess seed germinability of Synthyris bullii seeds collected from 2008 to 2011 across its range. Overall, we found regardless of seed age, locality (i.e., site and state), and maternal environment (i.e., open, semi-shaded, and shaded) seeds are still viable. Although values were low for seed germination and seedling survivorship, the results of this study are encouraging and point to seed harvesting and storage as one way to preserve this species.
TL;DR: In this paper, the authors used a randomized block experiment in an outdoor mesocosm facility to test for spawning substrate preferences of imperiled coastal plain snubnose darters.
Abstract: The Yazoo Darter Etheostoma raneyi is a small imperiled snubnose darter endemic to Upper Gulf Coastal Plain streams in north-central Mississippi. Installation of rip-rap and wood is being considered in an effort to increase suitable habitat and spawning substrate for the species. In common with other snubnose darters, Yazoo Darters attach their eggs to appropriate spawning substrate. However, it is not known if Yazoo Darters, or other imperiled Coastal Plain snubnose darters, will use rock substrate for spawning given it is almost entirely absent from streams of occurrence. If Yazoo Darters show no preference between wood and rock (rip-rap) for spawning, management would have greater flexibility when designing stream habitat installations for imperiled Coastal Plain snubnose darters, because the installation of rip-rap is much less expensive and time consuming than installation of wood. We used a randomized block experiment in an outdoor mesocosm facility to test for spawning substrate preferences. We counted >7600 eggs and Yazoo Darters used both substrates but used wood more than twice as often as rip-rap. Though we cannot recommend habitat installations using only rip-rap, any installation using a mix of wood and rip-rap will enhance spawning habitat for the Yazoo Darter and at least four other imperiled Coastal Plain snubnose darters.
TL;DR: Prescribed fire may increase nest predation of artificial nests, indicating a possible impact on ground-nesting grassland birds.
Abstract: Grazing differentially affects both the abundance and breeding success of grassland birds (e.g., due to differences in bird species' preferences for sparse or dense vegetation structure, nest predator response to grazing, and/or trampling of nests). Coupled with prescribed fire, grazing impacts can be compounded by pyric herbivory—the preference of grazers to choose newly-burned sites in which to graze. The purpose of this study was to determine how a recent re-introduction of American bison (Bison bison) coupled with prescribed fire may impact grassland bird nests. Artificial nests were used to determine if grazing and fire impacted nest success, total mammalian depredation, and depredation by the most common nest predator, mice (Peromyscus spp.). Artificial nests were placed in sites with and without bison before (2014) and after bison re-introduction (2015–2018); sites had fire return intervals from 1–2 y. We found the re-introduction of bison had a negligible influence on nest success and total mammalian depredation. However, nest success was lower in burned sites compared to unburned sites. The decrease in nest success correlated with an increase in total proportion of depredation events in burned sites compared to unburned sites. In addition, the proportion of Peromyscus spp. depredation events was marginally higher in burned sites compared to unburned sites. Although predation by Peromyscus increased after bison re-introduction, prescribed fire differences drove this change. Our results suggest prescribed fire may increase nest predation of artificial nests, indicating a possible impact on ground-nesting grassland birds. In contrast, bison had a negligible impact on artificial nest success in the first 4 y following their re-introduction.