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Camera trapping is a standard tool in ecological research and wildlife conservation. Study designs, particularly for small-bodied or cryptic wildlife species often attempt to boost low detection probabilities by using non-random camera placement or baited cameras, which may bias data, or incorrectly estimate detection and occupancy. We investigated the ability of non-baited, multi-camera arrays to increase detection probabilities of wildlife. Study design components were evaluated for their influence on wildlife detectability by iteratively parsing an empirical dataset (1) by different sizes of camera arrays deployed (1-10 cameras), and (2) by total season length (1-365 days). Four species from our dataset that represented a range of body sizes and differing degrees of presumed detectability based on life history traits were investigated: white-tailed deer (Odocoileus virginianus), bobcat (Lynx rufus), raccoon (Procyon lotor), and Virginia opossum (Didelphis virginiana). For all species, increasing from a single camera to a multi-camera array significantly improved detection probability across the range of season lengths and number of study sites evaluated. The use of a two camera array increased survey detection an average of 80% (range 40-128%) from the detection probability of a single camera across the four species. Species that were detected infrequently benefited most from a multiple-camera array, where the addition of up to eight cameras produced significant increases in detectability. However, for species detected at high frequencies, single cameras produced a season-long (i.e, the length of time over which cameras are deployed and actively monitored) detectability greater than 0.75. These results highlight the need for researchers to be critical about camera trap study designs based on their intended target species, as detectability for each focal species responded differently to array size and season length. We suggest that researchers a priori identify target species for which inference will be made, and then design camera trapping studies around the most difficult to detect of those species.

Camera trapping is a standard tool in ecological research and wildlife conservation. Study designs, particularly for small-bodied or cryptic wildlife species often attempt to boost low detection probabilities by using non-random camera placement or baited cameras, which may bias data, or incorrectly estimate detection and occupancy. We investigated the ability of non-baited, multi-camera arrays to increase detection probabilities of wildlife. Study design components were evaluated for their influence on wildlife detectability by iteratively parsing an empirical dataset (1) by different sizes of camera arrays deployed (1-10 cameras), and (2) by total season length (1-365 days). Four species from our dataset that represented a range of body sizes and differing degrees of presumed detectability based on life history traits were investigated: white-tailed deer (Odocoileus virginianus), bobcat (Lynx rufus), raccoon (Procyon lotor), and Virginia opossum (Didelphis virginiana). For all species, increasing from a single camera to a multi-camera array significantly improved detection probability across the range of season lengths and number of study sites evaluated. The use of a two camera array increased survey detection an average of 80% (range 40-128%) from the detection probability of a single camera across the four species. Species that were detected infrequently benefited most from a multiple-camera array, where the addition of up to eight cameras produced significant increases in detectability. However, for species detected at high frequencies, single cameras produced a season-long (i.e, the length of time over which cameras are deployed and actively monitored) detectability greater than 0.75. These results highlight the need for researchers to be critical about camera trap study designs based on their intended target species, as detectability for each focal species responded differently to array size and season length. We suggest that researchers a priori identify target species for which inference will be made, and then design camera trapping studies around the most difficult to detect of those species.

Learning and resolving uncertainty should be important components of management decisions, but not every type of uncertainty is equally important to resolve. For rare, threatened, and endangered species, information may be limited and there is often great urgency to halt potential population declines. Therefore, the most important uncertainties are those that would lead to different decisions intended to improve outcomes for species of interest. The New England cottontail (Sylvilagus transitionalis) is an endemic species to the northeastern United States and is listed as a species of special concern, threatened, or endangered in all states in its current range. States within the historical New England cottontail range have made substantial investments in habitat management, captive breeding, and research, but considerable demographic, management, and monitoring uncertainties remain. Connecticut is the geographic core of the current range of the species and therefore has been the focus of many management efforts, including improving habitat, creating new habitat patches, removing eastern cottontails (Sylvilagus floridanus), and releasing captive‐bred New England cottontails. We used a value of information analysis to identify the optimal management decision given current uncertainty and to evaluate how sources of uncertainty might lead to changes in management decisions. Given the current understanding of the New England cottontail in Connecticut, we identified the optimal management decision as improving existing habitat patches without monitoring for the species and managers could expect a 3.4% increase in populations if decision‐making uncertainty could be fully resolved. Multiple sources of uncertainty influenced results, but variation in New England cottontail density and the response of the species to the removal of eastern cottontails were most likely to result in changes to management decisions. At lower New England cottontail densities, releasing captive‐bred individuals competed with improving habitat as the optimal management action. Accounting for the value of information benefits New England cottontail management by guiding research efforts toward information that is most beneficial for decision‐makers and providing insights into parameter thresholds that would lead to changes in management decisions. [ABSTRACT FROM AUTHOR]

We evaluated spatiotemporal changes in the mean and variation in largemouth bass (Micropterus salmoides) mercury concentrations over three discrete time periods (1995, 2005–2006, and 2019–2021) across 56 Connecticut waterbodies. We detected largemouth bass raw mercury concentrations that exceeded the US Environmental Protection Agency (USEPA) Fish Tissue Residue Criterion (≥ 0.30 µg g−1 ww) in 75.1%, 63.3%, and 47.7% of all fish sampled during 1995, 2005–2006, and 2019–2021, respectively. Total length (TL)-adjusted largemouth bass mercury concentrations declined across all ecoregions in Connecticut between subsequent sampling periods but increased between 2005–2006 and 2019–2021 in the Northwest Hills/Uplands ecoregion. The coefficient of variation (CV) of largemouth bass TL-adjusted mercury concentrations increased through time, increasing from 25.78% during 1995 to 36.47% during 2019–2021. The probability of a largemouth bass having a raw mercury concentration > 0.30 µg g−1 ww increased with total length (TL), but the TL with a 50% probability varied across ecoregions and periods. The variation in largemouth bass mercury concentrations highlights the roles that changes to individual behaviors, food web structure, lake properties, and legacy mercury may play in shaping broad patterns and trends in mercury consumption risks. [ABSTRACT FROM AUTHOR]

Headwater stream networks are considered heterogeneous riverscapes, but it is challenging to characterize spatial variability in demographic rates. We estimated site-scale (50 m) survival of adult (>age 1+) brook trout (Salvelinus fontinalis) within two intensively surveyed headwater stream networks by applying an open-population N-mixture approach to count data collected over two consecutive summers. The estimated annual apparent survival rate was 0.37 (95% CI: 0.28-0.46) in one network and 0.31 (95% CI: 0.15-0.45) in the other network. In both networks, trout survival was higher in stream sites characterized by more abundant pool habitats. Trout survival was negatively associated with mean depth in one network and positively associated with stream gradient in the other. Stream temperature was not related to trout survival in either network, possibly because the majority of sites were thermally suitable. A similar analytical approach can be useful for inferring survival rates when count data are available over space and time but individual tagging is not feasible. Si les reseaux hydrographiques de tete de bassin sont consideres comme etant des paysages fluviaux heterogenes, la caracterisation de la variabilite spatiale des taux demographiques constitue un defi. Nous avons estime le taux de survie a l'echelle du site (50 m) des ombles de fontaine (Salvelinus fontinalis) adultes (age> 1+ an) dans deux reseaux hydrographiques de tete de bassin intensement etudies en appliquant une approche de melange de N de populations ouvertes a des donnees de comptage recueillies sur deux etes consecutifs. Des taux de survie annuelle apparents de 0,37 (IC a 95 %: 0,28-0,46) et 0,31 (IC a 95 %: 0,15-0,45) ont respectivement ete estimes pour les deux reseaux. Dans ces deux reseaux, la survie des ombles etait plus elevee dans les sites caracterises par des habitats de fosses plus abondants. La survie des ombles etait negativement associee a la profondeur moyenne dans un reseau et positivement associee au gradient des cours d'eau dans l'autre. La temperature du cours d'eau n'etait par reliee a la survie des ombles dans l'un ou l'autre des reseaux, possiblement en raison du fait que la majorite des sites etaient convenables sur le plan thermique. Une telle approche analytique peut etre utile pour estimer les taux de survie quand des donnees de comptage dans le temps et l'espace sont disponibles, mais que le marquage individuel n'est pas envisageable. [Traduit par la Redaction], Introduction Quantifying species-habitat relationships is critical in effective fisheries management and conservation. Many previous studies have examined associations of stream fishes with fluvial habitat characteristics. Lotic habitat heterogeneity has been [...]

We used multiseason, multistate patch occupancy models to investigate habitat use of a regionally rare minnow (bridle shiner, Notropis bifrenatus) within a difficult-to-sample, swampy stream system by defining occupancy states as coarse abundance categories (i.e., none, some, many). Habitat patches were repeatedly subsampled during three sampling periods spanning June to August 2011 using a nonstandard purse-and-lift method with a seine net, as poorly defined shorelines, unconsolidated substrate, and emergent vegetation limited beaching and restricted possible sampling locations. Detection probabilities increased from June to August, likely due to increasing catch per effort as age 0 became vulnerable to the gear, supported by the probability of detection being greater when the species was at high abundance, given occupancy. The probability of a habitat patch being occupied increased with the percent of macrophyte cover and decreased with increasing distance from another occupied patch. Decreasing mean depth showed a weak relationship to high abundance, given a patch was occupied. In summary, the multistate occupancy analytical approach was highly informative for developing quantitative habitat relationships and was seen as an effective framework for evaluating habitat use of aquatic organisms that inhabit environments inherently difficult to sample for which imperfect detection and sampling efficiency are of concern. Nous avons utilise un modele multi-etats et multi-saisons d'occupation de parcelles pour etudier l'utilisation de l'habitat par le mene d'herbe (Notropis bifrenatus), une espece rare a l'echelle regionale, dans un chevelu hydrographique marecageux difficile a echantillonner, en definissant des etats d'occupation selon des categories d'abondance tres larges (c.-a-d., aucun, quelques-uns, beaucoup). Les parcelles d'habitat ont ete echantillonnees a plusieurs reprises durant trois periodes d'echantillonnage de juin a aout 2011, selon une methode non standard de fermeture-et-remontee d'une senne, etant donne que la pietre definition des rives, le substrat non consolide et la vegetation emergente limitaient les possibilites d'echouage et le nombre de sites d'echantillonnage possibles. La probabilite de detection augmentait de juin a aout, probablement en raison de l'augmentation des captures par unite d'effort a mesure qu'augmentait la vulnerabilite des individus de 0 an a l'engin, en plus d'une probabilite de detection accrue quand l'abondance de l'espece est grande dans une parcelle occupee. La probabilite d'occupation d'une parcelle d'habitat augmentait parallelement au pourcentage de couverture de macrophytes et diminuait parallelement a l'augmentation de la distance entre cette parcelle et une autre parcelle occupee. Un faible lien inverse est ressorti entre la profondeur moyenne et l'abondance dans les parcelles occupees. En resume, l'approche multi-etats d'analyse de l'occupation s'est averee tres instructive pour la determination de relations quantitatives relatives a l'habitat et constitue un cadre efficace d'evaluation de l'utilisation de l'habitat par les organismes aquatiques qui habitent des milieux difficiles a echantillonner pour lesquels l'efficacite de la detection et de l'echantillonnage peut s'averer problematique. [Traduit par la Redaction], Introduction A high proportion of threatened and endangered freshwater fishes in North America are small-bodied species, particularly darters in the family Percidae and minnows in the family Cyprinidae (Olden et [...]

Within an ongoing round-the-clock radiotracking project, a subset of adult flathead catfish Pylodictis olivaris (n = 6) was continuously radio-tracked for 24 h to determine detailed diel movement path characteristics and activity in two Missouri streams. The ongoing radiotracking revealed that only a small percentage of point-in-time relocations were recorded as moving, while the majority (greater than 90% for every hour of the day) found fish stationary. The continuously-tracked subset of catfish generally moved by making discrete directed movements from one location to another, with locations corresponding to a physical habitat feature (large woody debris, clay point, undercut bank). All fish revisited locations during the 24-h tracking efforts. Movements were less than 100 m during early afternoon and the first 2 h after sunset, with longer movements undertaken from 2100 through the night to the 0500 hour, ceasing at sunrise. Movement paths had a median distance of 641.16 m with a median activity radius of 66.55 m. Fish spent a median 23.33 h stationary and 0.67 h moving during the diel cycle. The continuous tracking effort resulted in finer resolution and detail than was evident in the larger, typical point-in-time tracking dataset which did not highlight an early afternoon activity period, perhaps due to short, quick movements made at that time.

Stream connectivity promotes resilience and population viability of aquatic organisms. Landscape genetic approaches, traditionally applied to terrestrial systems, may reveal important watershed‐level dynamics that influence connectivity. Additional validation would improve understanding of how the models perform when gene flow is constrained to dendritic networks. The objectives of this study were to use simulations to assess the utility of landscape genetics analyses in dendritic stream networks and investigate riverscape variables influencing gene flow among brook trout Salvelinus fontinalis populations in headwater streams.We used an individual‐based simulation program to simulate different dispersal scenarios and used combinations of landscape genetic models, model selection methods, and genetic metrics to determine the best combination for riverscape systems. We also sampled brook trout from 76 headwater streams in two watersheds (c. 1,000 km2) in Connecticut, U.S.A. to assess connectivity and riverscape influences on genetic structuring.Gravity models with Bayesian information criterion (BIC) selection were the most accurate (>85%) landscape genetic models that consistently identified the correct simulated gene flow barrier. However, all models performed poorly when unidirectional barriers were simulated without a distance‐based dispersal limitation. Excluding this scenario, model accuracy for the gravity models using BIC selection was >90% across multiple genetic metrics, validating the application of landscape genetic models to riverscape systems.We found highly variable levels of brook trout genetic connectivity (FST range 0.01–0.19) at the watershed level (5–15 river km). Gravity models identified increases in upstream impervious surfaces and decreases in riparian tree canopy cover as riverscape variables associated with increases in genetic differentiation in one watershed, while the other watershed was consistent with an isolation by distance pattern.In this study we used demogenetic (i.e. combined demographic and genetic) simulations to demonstrate the utility of landscape genetics techniques in dendritic river networks. Our empirical genetic study documented gene flow among headwater populations of brook trout at the watershed level and also suggested connectivity can be limited by watershed development. Incorporating the heterogeneity of riverscapes into connectivity‐focused conservation planning is essential to the development of effective restoration actions, and landscape genetics approaches can be useful tools to identify watershed‐level connectivity in stream systems. [ABSTRACT FROM AUTHOR]

ABSTRACT.--Shortnose gar foraged on spent periodical cicadas floating on the surface during a mass coemergence of 13- and 17-y broods. The largest gar in each pool of an observed stream [...]

This research described coastal habitat characteristics at a landscape scale and followed a geospatial modelling approach to predict the probability of habitat use by the population of Atlantic horseshoe crabs ( Limulus polyphemus) in Long Island Sound (LIS, USA). This approach was developed to aid in decision-making regarding management of horseshoe crab spawning locations., Geospatial data layers were created within which beach slope, wave exposure, surface substrate type, and distance from offshore aggregations of crabs (i.e. hotspots) were summarized for beaches in the western, central, and eastern regions of the Connecticut coast of LIS., Spawning abundances derived from field surveys conducted in May and June of 2009 and 2010 were used with remotely-sensed habitat characteristics to develop a resource selection function from a candidate model set based on polytomous logistic regression., A single best model (Akaike weight = 0.97) for predicting the probability of habitat use by spawning horseshoe crabs was selected using an information-theoretic approach. The parameter estimates predicted a greater probability of habitat use with increasing slope, decreasing wave exposure, and decreasing distance from offshore hotspots., Small 'pocket' beaches surrounded by rocky headlands, marshes, and developed areas are the typical habitat available to support horseshoe crab spawning in LIS. As spawning densities in LIS are relatively small and suitable spawning habitat is fragmented, geospatial methods are especially useful for identifying high-use sites and maximizing the conservation value of management actions., Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The Bridle ShinerNotropis bifrenatusis a small, rare minnow species native to northeastern streams and lakes. It is declining over most of its range and currently is listed as a species of concern in Connecticut. Surveys conducted with seine nets in the 1960s found Bridle Shiners at 56 locations statewide. In contrast, surveys conducted in the 1990s using electrofishing detected Bridle Shiners at 8 locations. Different sampling techniques made it difficult to assess what portion of the observed decline might be a sampling artifact, confounding efforts to assess the actual conservation status. We sampled 18 habitat patches in three Connecticut watersheds in 2012 to determine if seining for Bridle Shiners yielded a higher detection probability than backpack electrofishing. A multimethod occupancy estimation modeling approach, using the program PRESENCE, quantified the probability of correctly detecting Bridle Shiners by gear and as detection covaried with habitat features. Backpack electrofishing detection probability was lower and approximately half that of seining. The abundance of Bridle Shiners in the sample patch was the most supported covariate to detection and particularly aided detection for electrofishing. High mean water velocity improved the detection probability of backpack electrofishing and reduced that of seining. It is possible that the 1990s sampling underestimated the number of populations of Bridle Shiners, and a repeat survey of all historic locations using a seine is recommended. Received April 3, 2014; accepted September 15, 2014 [ABSTRACT FROM AUTHOR]