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Environmental DNA (eDNA) analyses have become invaluable for detecting and monitoring aquatic and terrestrial species and assessing site biodiversity within aquatic environments or soil. Recent studies have extended these techniques by using eDNA to identify the presence of aboveground terrestrial arthropods directly from vegetative surfaces. However, while the dynamics of eDNA state, transport, and fate (its “ecology”) have been explored within aquatic environments and soil, they have yet to be explored within aboveground terrestrial systems. Here, we explore the ecology of terrestrial eDNA deposited by fluid‐feeding arthropods on leaf surfaces. We carried out a series of experiments to evaluate the optimal filter pore size for intracellular eDNA collection, how eDNA is affected by rain events, and its degradation rate under different solar radiation conditions. We found that the captured concentration of intracellular eDNA was not significantly affected by an increase in filter pore size, suggesting a wide range of viable pore size options exist for targeting intracellular eDNA. We also found extracellular eDNA from fluid excrement degrades more rapidly than intracellular when exposed to solar radiation, indicating the latter is a more viable target for collection. Finally, we identified that rainfall or mist will remove most terrestrial eDNA present on vegetation surfaces. We provide researchers and environmental managers key insights into successfully designing and carrying out aboveground terrestrial arthropod eDNA surveys that maximize detection probability.

Recent methodological advances permit surveys for terrestrial insects from the direct collection of environmental DNA (eDNA) deposited on vegetation or other surfaces. However, in contrast to well‐studied aquatic applications, little is known about how detection rates for such terrestrial eDNA‐based surveys compare with conventional survey methods. Lycorma delicatula, the spotted lanternfly, is an emerging invasive insect in eastern North America, and a significant ecological and economic pest of forested and agricultural systems, especially grapes. During fall 2019, we conducted two rounds of paired eDNA and visual surveys for spotted lanternflies within 48 plots at 12 vineyards in New Jersey, USA. We compared detection probabilities within a multimethod occupancy modeling framework and used the results to extrapolate and inform survey design. The probability of detecting spotted lanternflies given presence in a plot was over two times higher for eDNA (84%) versus visual surveys (36%). In mid‐September, lanternfly eDNA was detected at five plots in three vineyards, while visual surveys revealed only a single individual in one plot. In early October, after dispersal of lanternflies into vineyards, lanternfly eDNA was detected in 12 plots within six vineyards compared with visual detections in six plots in two vineyards. Extrapolations based on detection and local‐scale occupancy rates indicate that only five and 12 plots would have been needed to positively detect lanternfly presence with 95% confidence using eDNA in contrast to 14 and 29 plots with visual surveys alone, respective to survey rounds. Log‐linear models revealed that visual counts of lanternflies were positively related to eDNA concentrations (R2 = 71%). We provide some of the first quantitative evidence to support the enhanced sensitivity of terrestrial eDNA approaches compared with conventional methods. Such methods can augment efforts to combat invasive species through improved ability to delimit invasion fronts, identify satellite populations, and confirm local eradications.

Reptiles are increasingly of conservation concern due to their susceptibility to habitat loss, emerging disease, and harvest in the wildlife trade. However, reptile populations are often difficult to monitor given the frequency of crypsis in their life history. This difficulty has left uncertain the conservation status of many species and the efficacy of conservation actions unknown. Environmental DNA (eDNA) surveys consistently elevate the detection rate of species they are designed to monitor, and while their use is promising for terrestrial reptile conservation, successes in developing such surveys have been sparse. We tested the degree to which inclusion of surface and soil eDNA sampling into conventional artificial-cover methods elevates the detection probability of a small, cryptic terrestrial lizard, Scincella lateralis. The eDNA sampling of cover object surfaces with paint rollers elevated per sample detection probabilities for this species 4-16 times compared with visual surveys alone. We readily detected S. lateralis eDNA under cover objects up to 2 weeks after the last visual detection, and at some cover objects where no S. lateralis were visually observed in prior months. With sufficient sampling intensity, eDNA testing of soil under cover objects produced comparable per sample detection probabilities as roller surface methods. Our results suggest that combining eDNA and cover object methods can considerably increase the detection power of reptile monitoring programs, allowing more accurate estimates of population size, detection of temporal and spatial changes in habitat use, and tracking success of restoration efforts. Further research into the deposition and decay rates of reptile eDNA under cover objects, as well as tailored protocols for different species and habitats, is needed to bring the technique into widespread use.El interés por la conservación de los reptiles es cada vez mayor debido a su susceptibilidad ante la pérdida del hábitat, enfermedades emergentes y la captura para el mercado de fauna. Sin embargo, las poblaciones de reptiles son difíciles de monitorear por lo frecuente que es la cripsis en sus historias de vida. Esta dificultad deja incierto el estado de conservación de muchas especies y desconocida la eficacia de las acciones de conservación. Los censos de ADN ambiental (DNAa) elevan sistemáticamente la tasa de detección de las especies que monitorean, y aunque su uso es prometedor para la conservación de los reptiles terrestres, han sido escasos los éxitos en el desarrollo de dichos censos. Analizamos el grado al que la inclusión del muestreo de DNAa superficial y del suelo a los métodos convencionales de cobertura artificial eleva la probabilidad de detección de una pequeña lagartija terrestre críptica: Scincella lateralis. El muestreo de DNAa de las superficies con cobertura de objetos con rodillos de pintura elevó las probabilidades de detección por muestra para esta especie 4-16 veces más que los censos visuales. Detectamos fácilmente el DNAa de S. lateralis bajo los objetos de cubierta hasta dos semanas después de la última detección visual y en algunos objetos de cubierta en donde no se había observado en los meses previos a S. lateralis. Con suficiente intensidad de muestreo, el análisis de DNAa del suelo bajo objetos de cubierta produjo probabilidades de detección por muestra comparables como métodos de rodillo superficial. Nuestros resultados sugieren que la combinación del DNAa y los métodos de objetos de cobertura puede incrementar considerablemente el poder de detección de los programas de monitoreo de reptiles, lo que permite estimaciones más precisas del tamaño poblacional, detección de los cambios espaciales y temporales en el uso de hábitat y el éxito de rastreo de los esfuerzos de restauración. Además, se necesita la investigación sobre las tasas de depósito y descomposición del DNAa de reptiles bajo objetos de cubierta, así como los protocolos hechos para diferentes especies y hábitats, para que la técnica entre al uso difundido.

Environmental DNA (eDNA) analysis has become a valuable tool for detecting aquatic and terrestrial species for monitoring efforts and site biodiversity assessments. However, if aboveground terrestrial eDNA surveys are to be widely adopted, it is necessary to first understand how terrestrial conditions affect the state, transport, and ultimate fate (or ‘ecology’) of terrestrially deposited eDNA. Many of the processes that affect the state, transport, and fate of eDNA in aquatic environments may not be applicable in aboveground systems, warranting an exploration of the terrestrial processes that likely do affect eDNA. Here we explore the ecology of aboveground terrestrial eDNA through a series of experiments evaluating the optimal filter pore size for intracellular eDNA collection, how eDNA is affected by rain events, and its degradation rate under different solar radiation conditions. We found that the captured concentration of intracellular eDNA was not significantly affected by an increase in filter pore size, suggesting there is a wide range of viable pore size options for targeting intracellular eDNA. We also found extracellular eDNA degrades more rapidly than intracellular forms when exposed to solar radiation, indicating the latter is a more viable target for collection. Finally, we identified that rainfall or mist will remove most terrestrial eDNA present on vegetation substrate. This study provides researchers and managers key insights into successfully designing and carrying out terrestrial eDNA surveys that maximize detection probability and minimize false positive results.

1. Efforts to monitor and conserve populations and ecosystems in human-dominated landscapes can benefit from an empirical social–ecological systems approach., 2. Here we illustrate how latent variable structural equation modelling of regional time series data can effectively describe interconnected drivers of population fluctuations in dynamic landscapes and can help to reveal previously unknown system drivers., 3. Using a declining farmland-dependent bird species (Ammodramus savannarum) in the eastern United States (1994–2015) as a case study, our analysis reveals how farm management decisions drive population fluctuations (R2 = 20%), while management is in turn highly influenced by climate (R2 = 23%–51%), but not by regional conservation spending., 4. Synthesis and applications. Structural equation modelling revealed potential social–ecological pathways for halting regional population declines in a grassland bird, the Grasshopper Sparrow. Lower population growth rates followed years of higher hay yields (~4 percentage points per metric ton increase in hay yield) and later harvests (~2 percentage points per 10-day delay in harvest). Thus, one pathway for stabilising regional populations could involve compensating farmers for reducing hay harvests, potentially requiring a six-fold increase in current annual agri-environmental conservation spending.

Cryptic colouration in crustaceans, important for both camouflage and visual communication, is achieved through physiological and morphological mechanisms that are sensitive to changes in environmental conditions. Consequently, ocean warming and ocean acidification can affect crustaceans’ biophotonic appearance and exoskeleton composition in ways that might disrupt colouration and transparency. In the present study, we measured growth, mineralization, transparency, and spectral reflectance (colouration) of the caridean grass shrimp Hippolyte californiensis in response to pH and temperature stressors. Shrimp were exposed to ambient pH and temperature (pH 8.0, 17 °C), decreased pH (pH 7.5, 17 °C), and decreased pH/increased temperature (pH 7.5, 19 °C) conditions for 7 weeks. There were no differences in either Mg or Ca content in the exoskeleton across treatments nor in the transparency and spectral reflectance. There was a small but significant increase in percent growth in the carapace length of shrimp exposed to decreased pH/increased temperature. Overall, these findings suggest that growth, calcification, and colour of H. californiensis are unaffected by decreases of 0.5 pH units. This tolerance might stem from adaptation to the highly variable pH environment that these grass shrimp inhabit, highlighting the multifarious responses to ocean acidification, within the Crustacea.

Agricultural grasslands such as hayfields and pastures frequently act as ecological traps for grassland birds because of harvest practices that interfere with successful nesting. Conservation measures that improve reproductive success while allowing farmers to maintain agricultural outputs are needed to help stem widespread grassland bird population declines. We evaluated leaving uncut patches ("refugia") within harvested hayfields to provide cover, reduce field abandonment, and promote renesting by three grassland species: Bobolink (Dolichonyx oryzivorus), Grasshopper Sparrow (Ammodramus savannarum), and Eastern Meadowlark (Sturnella magna). In 2014-2016, we left five refugia (0.25 ha each) within a 23-ha hayfield in New Jersey, USA. We found refugia were used more relative to cut areas by Bobolink and Grasshopper Sparrow, but not by Eastern Meadowlark. The presence of refugia also appears to have reduced field abandonment following harvest in all three years for Bobolink and Grasshopper Sparrow when compared to two adjacent fields that lacked refugia. We observed territorial singing, but no evidence of renesting in refugia following harvest, though this may relate to the relatively late harvest dates (26 Jun-3 Aug). Response patterns were consistent over the three years of the study and suggest that leaving small refugia within active hayfields could be a valuable supplement to current management incentive approaches.

The rapid expansion of wind power development in recent years has accentuated the need to develop standard guidelines for identifying, assessing, and monitoring potential impacts to birds and bats. Although postconstruction mortality estimates generally take into account well-established sources of bias, including searcher efficiency and scavenging loss, methods for addressing these biases can be improved. Currently used bias-adjustment methods differ across studies, do not explicitly account for factors that may affect initial bias estimates, and often use averaged or assumed levels of bias. We examined scavenging and detection trial data from a 3-y study at a small, terrestrial wind-farm in coastal New Jersey. Logistic regression models indicated that carcass size, substrate, and observer all affected carcass detection rates, with larger carcasses more likely to be detected than smaller carcasses, and those located on bare ground or grass more likely to be detected than those on gravel. Known-fate mark–recapture models indicated that scavenging rates were highest within the first 3 d of placement, with some variation among seasons. We suggest that empirically based estimates of factors affecting observer detection and scavenging loss be generated for individual wind-farm mortality studies, because they likely vary across sites and could heavily bias resulting adjustment factors and mortality estimates.

We monitored Common Nighthawk (Chordeiles minor) nests in a managed grassland in the New Jersey Pine Barrens in 2009 and 2010, and assessed habitat selection by comparing vegetation characteristics at nests with random locations. We found relatively high nest survival with an estimated 79% chance of survival through incubation (daily survival rate = 0.987, n = 16 nests); predation was the most common cause of failure (n = 2). Movements of young (up to 45 m from the original nest site) were frequent, which introduced uncertainty that prevented us from estimating survival through fledging. Nest sites had significantly more open ground cover (e.g., sand, lichen) than random sites, as well as less shrub and grass cover, shallower litter, and lower mean vegetation height.

Streamers of hanging plant debris (nest tails) are commonly used for nest concealment by tropical Tyrannid flycatchers. Of the 35 species of Tyrannid flycatchers that regularly occur in temperate North America, only the Acadian flycatcher (Empidonax virescens) retains use of nest tails. To better understand the prevalence and possible function of nest tails in temperate breeding Acadian flycatchers, we investigated 145 nests in two habitat types (deciduous and hemlock (Tsuga Canadensis) dominated) in southwestern Pennsylvania in 2006–2007. The primary constituent of nest tails was catkins of oak (Quercus sp.) and American beech (Fagus grandifolia) along with other plant debris entangled in arthropod silk. Debris availability was generally sparse but appeared more common on nest as opposed to randomly selected branches. An index of nest tail “prominence,” involving both the length and number of tails, was negatively related to nest height. Variation in nest survival rates was poorly explained by n...

Invasive insects pose a significant threat to biodiversity, often affecting entire communities through the destruction of foundation species. Eastern Hemlock (Tsuga canadensis [L.] Carr.) forests, which are unique habitats in eastern North America, are threatened by an introduced insect, the Hemlock Woolly Adelgid (Adelges tsugae Annand). Previous studies have found declines in the abundance of some forest bird species, including the Acadian Flycatcher (Empidonax virescens), with increasing infestation by Hemlock Woolly Adelgids. To identify potential mechanisms behind these declines, we studied abundance, breeding biology, and habitat selection of Acadian Flycatchers in 11 Eastern Hemlock-dominated riparian sites in Pennsylvania and New Jersey, representing a continuum of infestation levels, in 2001–2002 and 2006–2007. Eastern Hemlock supported 90% of all nests and was used more as a nesting substrate than expected at most sites. We found ∼70% fewer breeding pairs at heavily infested sites, tho...

The anticipated effects of CO2-induced ocean acidification on marine calcifiers are generally negative and include dissolution of calcified elements and reduced calcification rates. Such negative effects are not typical of crustaceans for which comparatively little ocean acidification research has been conducted. Crustaceans, however, depend on their calcified exoskeleton for many critical functions. Here, we conducted a short-term study on a common caridean shrimp, Lysmata californica, to determine the effect of CO2-driven reduction in seawater pH on exoskeleton growth, structure and mineralization and animal cryptic coloration. Shrimp exposed to ambient (7.99 ± 0.04) and reduced pH (7.53 ± 0.06) for 21 days showed no differences in exoskeleton growth (percent increase in carapace length), but the calcium weight percent of their cuticle increased significantly in reduced pH conditions, resulting in a greater Ca:Mg ratio. Cuticle thickness did not change, indicating an increase in the mineral to matrix ratio, which may have mechanical consequences for exoskeleton function. Furthermore, there was a 5-fold decrease in animal transparency, but no change in overall shrimp coloration (red). These results suggest that even short-term exposure to CO2-induced pH reduction can significantly affect exoskeleton mineralization and shrimp biophotonics, with potential impacts on crypsis, physical defense and predator avoidance.

Grasslands associated with airfields in the northeastern United States (both military and civilian) often support large numbers of regionally rare grassland birds. As grassland habitat area in the region continues to decline, the role that large airfields play in maintaining populations of these species is likely to increase. Despite this, relatively little is known regarding reproductive success in these habitats, and whether they act as population sources or sinks. This is a particular concern because vegetation management on airfields often involves regular mowing during the summer breeding season, a practice presumed to be harmful to nesting success. To obtain a general picture of grassland bird reproductive success on regional airfields, and to examine possible factors that may be affecting it (including mowing), we conducted a nest monitoring study in 2009 on three military airfields in the Mid-Atlantic and Northeast: Westover Air Reserve Base (Massachusetts), Lakehurst Naval Air Engineering Station (New Jersey), and Patuxent River Naval Air Station (Maryland). Nests of two target species (grasshopper sparrow (Ammodramus savannarum) and eastern meadowlark (Sturnella magna) and of other grassland-obligate species were located and monitored at regular intervals until success (fledging) or failure. We measured vegetation characteristics around each nest, and through direct observation and cooperation with mowing crews were able to determine: 1) if a nest was located in a regularly mowed area, 2) if a nest was directly mowed over while active, and 3) the condition of each nest immediately following a mow. We calculated daily nest survival rates (DSR), and examined the effects of various predictor variables using logistic modeling in program MARK. We also modeled the mean number of fledglings produced per nest using Generalized Linear Models (GLM).