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Here we report on the long-term monitoring of Carcinus maenas (European Green Crab) populations on an intertidal region of a cobble beach in Maine conducted from 2011 to 2021. The number of Green Crabs collected fluctuated between 129 and 474 individuals per sample event. We collected crabs twice each year, with a total number collected of 389 to 798 per year. In addition, we collected Hemigrapsus sanguineus (Asian Shore Crab) in 2 sample years (2019 and 2021), accounting for only 7 individuals. No compelling relationships between Green Crab densities and sea-water temperature, average carapace width, or year of the collection were revealed.
Standardized sampling of fishes is either probabilistic (i.e., random) or non-probabilistic (i.e., fixed), with each having advantages and disadvantages. Our study objective was to evaluate whether a fixed site-survey design for early detection monitoring of non-native fishes could be improved by modifying fixed site selection and adding random sampling. Results were largely similar but varied by evaluation metric; accumulation curves of species suggested that performance of the fixed survey design was 10% higher than the modified survey and also accumulated species significantly faster from 1 to 42 units of effort. Results indicated the fixed site survey previously took advantage of the patchiness in fish distribution, leaving little potential efficiency to gain using the modified survey design. We would like to emphasize that the modified survey design was effective, just not as effective as the fixed site survey, and could likely optimize early detection monitoring (EDM) for programs with less available fish data to draw observations from or if only random sampling was used for monitoring.
Invasive plants often drastically alter food webs. Small-mammal assemblages may be greatly impacted by invasive plants, which often provide cover from predators. In addition, a less-studied potential impact is the possibility that small mammals use invasive plants as a food resource. We quantified small mammal giving-up densities (GUDs) by offering fruits of 5 common invasive shrubs and 1 native shrub in adjacent meadow and forest habitats in Pennsylvania. The study ran for two 48-hour sessions in November in 2 consecutive years with different combinations of shrub fruits available to small mammals within buckets that also contained Panicum miliaceum (Proso Millet), and sand. While some degree of differences in foraging activity could be accredited to annual variation, significant differences in GUDs among fruit species and between habitats were detected. The fruits of the invasive shrubs Berberis thunbergia (Japanese Barberry), Ligustrum vulgare (Eurasian Privet), and Rhodotypos scandens (Jetbead) did not appear to be significantly foraged on by small mammals in either habitat. However, the woody liana Celastrus orbiculatus (Oriental Bittersweet) was readily consumed in both the forest and meadow. Fruits of the invasive shrub Eleagnus umbellata (Autumn Olive) was favored but only in meadow habitat, while fruits of the native shrub Lindera benzoin (Spicebush) were moderately foraged in the forest. Through this experiment, we were able to conclude that most woody plants included in this study offer fruits with limited perceived benefit. However, Oriental Bittersweet and Autumn Olive may represent important exceptions that could be influencing small-mammal foraging patterns in northeastern forest and meadow ecosystems.
Neotoma magister (Allegheny Woodrat) is a nocturnal, emergent rock-habitat specialist (i.e., inhabits rocky outcrops, boulderfields, and caves). Woodrat populations have declined range-wide due to habitat fragmentation, endoparasites, and interspecific competition. We estimated the diel activity curves of Allegheny Woodrats and assessed the effects of habitat type (exposed rock habitat/cave-exterior vs. cave-interior) and season (spring, summer, and fall) on curve shape. We also investigated the effect of 2 granivorous competitors' presence and activity curves (Peromyscus spp. and Tamias striatus [Eastern Chipmunk]) on woodrat activity. Additionally, we investigated whether the presence or absence of Procyon lotor (Raccoon), a primary carrier of Baylisascaris procyonis (Raccoon Roundworm), significantly affects the presence or absence of Allegheny Woodrats. We used remote-detecting cameras to document the diel cycles of Allegheny Woodrats and 2 competitors across 83 sites in western Virginia and 2 sites in West Virginia from 2017 to 2022. For 13,002 recorded events, we detected woodrats at 36 of 85 sites (3778 camera events). We observed a higher proportion of daytime activity by woodrats within cave interiors than cave exteriors. Allegheny Woodrat activity curves differed among seasons, with the greatest differences observed between summer and fall and with ∼80% activity overlap. These activity curves differed significantly when co-occurring with versus not co-occurring with a competitor. Additionally, Allegheny Woodrats showed an inverse activity rate with Peromyscus spp. Thus, our results suggest that competition avoidance via temporal partitioning occurs between these species. Allegheny Woodrats and Raccoons occurred together more often than expected suggesting the presence of woodrats is currently not reduced by the presence of Raccoons. Our remote-detecting camera data help elucidate relationships of Allegheny Woodrats with presumptive competitors, and open avenues for further investigation in Virginia.
Kentucky's breeding Haliaeetus leucocephalus (Bald Eagle) population began recovering in 1986, with a single nest, and has since expanded from the state's western portion to the central and eastern regions. We used aerial survey data to describe the spatiotemporal distribution of Bald Eagle nests in Kentucky, to examine changes in nest-site selection relative to natural and anthropogenic features, and to create a nesting-habitat suitability model. Our results highlight increased nesting near developed areas in recent years. Although nests in these areas productively contribute to populations, we note some considerations of increased risks associated with nesting in developed areas. We also provide predictions of available nesting areas and data to direct the future monitoring and management of Bald Eagles in Kentucky.
Some Canis lupus (Gray Wolf, hereafter Wolf) live in disjunct populations including Wisconsin's Central Forest Region (CFR), recolonizing there in the early 1990s. We examined how habitat factors and period of initial recolonization facilitated successful re-establishment of Wolves to this region. We divided this event into 3 periods: early (1994–1999), middle (2000–2005), and late (2006–2012). We defined habitat classes of individual pack territories as optimal, mixed, and marginal, based on: (1) percent public land, (2) percent agricultural land, and (3) road density. We analyzed the influence of time and habitat classes on pack territory size, winter pack size, pup presence, Wolf–human conflicts, human-caused Wolf mortalities, territory persistence, and reproductive performance. Pack demographics were similar across time, except pup presence was slightly lower during the middle period. Wolf–human conflicts increased over time and were correlated with population growth. Packs in marginal habitat were smaller in winter, exhibited lower reproductive performance, had more conflicts with humans, and experienced human-caused mortalities at rates 4 and 7 times higher than mixed and optimal habitats, respectively. We demonstrate that Gray Wolves tolerate some level of human-altered landscapes and identify demographic parameters that impact the Wolves' ability to survive in human-dominated landscapes.
The recent elevation of Lepomis peltastes (Northern Sunfish) as a separate species from L. megalotis (Longear Sunfish) has resulted in an incomplete understanding of the species' distribution in Illinois, as most occurrence records cannot differentiate the 2 species. We evaluated Northern Sunfish and Longear Sunfish specimens to identify morphological characteristics that could differentiate the 2 species; relative body depth, relative opercular flap length, and pectoral fin ray count were most useful. We reevaluated 867 Longear Sunfish specimens from the Illinois Natural History Survey Fish Collection and identified 103 as Northern Sunfish. Based on distribution of these specimens, it is probable that Northern Sunfish occur in 14 basins in the eastern half of Illinois, a range that extends farther south than was previously estimated.
Acer negundo (Boxelder) is a common tree in eastern North America. Fruits are paired samaras that mature in late summer but persist on trees for months. We examined temporal variation in predation rates by small mammals by attaching samaras to sewing bobbins in a forest in northeastern Wisconsin. We placed samaras in groups of 5 along transects and checked them regularly across 2 fall and 2 spring seasons to determine seed fates. Of the 6702 seeds, 15.26% were consumed, 81.41% were left intact, and 3.33% were aborted. Predation rates were higher in fall than in spring. Granivorous mammals did not secondarily disperse seeds but instead acted solely as seed predators. Releasing seeds over a longer period of time than other species of maples allows trees to increase seed survival by experiencing varying soil conditions and predation rates. Retained sterile fruits may act as decoys that decrease predation rates.
Ammospiza caudacuta (Saltmarsh Sparrow) is a salt marsh-nesting obligate species of greatest conservation concern due to decreasing populations and probable future threats, such as climate change-induced sea-level rise. Low reproductive success is a limiting factor to population growth for the species due to flooding, habitat loss, and predation. To further understand the effects of predation on nesting Saltmarsh Sparrows, we deployed camera traps at monitored nests in Jacob's Point salt marsh, Warren, RI, during the 2022 breeding period. In 2 instances of observed nest failure, camera traps captured the apparent depredation of eggs by Odocoileus virginianus (White-tailed Deer). We believe these to be the first documented cases of Saltmarsh Sparrow nest predation by White-tailed Deer. This finding has implications for the conservation of Saltmarsh Sparrows and for future management strategies aimed at increasing breeding success.
On 2 September and 7 October 2022, we captured post-copulatory pairs of Callinectes sapidus (Blue Crab) in Green Crab traps in Great Bay Estuary, NH. On the first occasion, the 2 crabs included a mature post-ecdysis (12–24 hour) female and a mature male, and the female's shed exoskeleton also remained in the trap. Both seminal receptacles had pink sperm plugs and were turgid with spermatophores, indicative of recent successful insemination. Details of the second capture mirrored the first with the exception that the exuvia was not in the trap. This is the first scientific reporting of Blue Crabs mating in Great Bay Estuary, NH, documenting an ongoing range expansion of a species with the potential to have major ecological and economic impacts.
The distribution of invasive Potamopyrgus antipodarum (New Zealand Mudsnail [NZM]) is relatively limited in eastern North America, with populations known in the Great Lakes basin and scattered locations in several Atlantic Slope drainages. Herein, we report the first documented occurrence of NZM in the Potomac River basin, based on collections at 2 adjacent sites in Falling Spring Branch, Franklin County, PA. We speculate the species was introduced into Falling Spring Branch via fishing gear from Susquehanna River basin tributaries in adjacent Cumberland County where there are documented NZM populations.
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