Better Representation Is Needed in U.S. Endangered Species Act Implementation

In the United States, the U.S. Fish and Wildlife Service uses the concepts of resilience, redundancy, and representation—often known as the “3Rs”—to guide implementation of the Endangered Species Act, which requires the U.S. government to designate imperiled species as threatened or endangered, and take action to recover them. The Service has done little, however, to relate the 3Rs to the statutory requirements of the Act. Here we focus on interpreting the concept of representation given core tenets of science and conservation policy. We show that the Service's current interpretation, which focuses on a narrow set of characteristics intrinsic to species that facilitate future adaptation, falls far short of a reasonable interpretation from the scientific literature and other policy, and has significant consequences for the conservation of threatened and endangered species, including those found in other countries. To illustrate the shortcomings in practice, we discuss the cases of the Lower 48 gray wolf (Canis lupus) delisting, the proposed Red-cockadedWoodpecker (Picoides borealis) downlisting, and the possible downlisting of the Canada lynx (Lynx canadensis). We then propose an alternative interpretation of representation that accommodates the Service's narrow interpretation and broadens it to include the importance of intraspecific variation for its own sake as well as extrinsic characteristics such as a species' role in ecological communities. We argue that this interpretation better reflects the intent of the Endangered Species Act, the best available science, and policy needs for conserving imperiled wildlife, all of which recognize the importance not only of preventing global extinction but also of preventing ecological extinction and extirpation across significant portions of a species' range.

Better representation is needed in Endangered Species Act implementation

The U.S. Fish and Wildlife Service uses the concepts of resilience, redundancy, and representation—often known as the “3Rs”—to guide implementation of the Endangered Species Act. The Service has done little, however, to relate the 3Rs to the statutory requirements of the Act. Here we focus on interpreting the concept of representation given core tenets of science and conservation policy. We show that the Service’s current interpretation, which focuses on a narrow set of characteristics intrinsic to species that facilitate future adaptation, falls far short of a reasonable interpretation from the scientific literature and other policy, and has significant consequences for the conservation of threatened and endangered species. To illustrate the shortcomings in practice, we discuss the case of the Lower 48 gray wolf (Canis lupus) delisting, the proposed Red-cockaded Woodpecker (Picoides borealis) downlisting, and the possible downlisting of the Canada lynx (Lynx canadensis). We then propose an alternative interpretation of representation that accommodates the Service’s narrow interpretation and broadens it to include the importance of intraspecific variation for its own sake as well as extrinsic characteristics such as a species’ role in ecological communities. We argue that this interpretation better reflects the intent of the Endangered Species Act, the best available science, and policy needs for conserving imperiled wildlife.

Life history trait differences in isolated populations of the endangered Red-cockaded Woodpecker

Changes in life history traits can reveal adaptations to changing environments. Red-cockaded Woodpeckers (Picoides borealis) are cooperative breeders that have specific reproductive habitat needs. We examined three separate sites in the southeastern United States to see how life history traits differed among isolated populations of Red-cockaded Woodpeckers from 1980 to 2013. We examined the life history traits group size, partial brood loss, number of fledglings, lay date, clutch size, and lifespan. Traits differed among sites, suggesting that populations were adapted to local conditions and different life history trade-offs were important under different environmental conditions at each site. At the two coastal sites in Florida and North Carolina, the family group sizes, lifespans, and partial brood loss were higher when compared to the inland site in North Carolina. Clutch size and number fledged were higher at the two northernmost sites when compared to the southern site. Identifying the differences in life history traits can allow more specific and effective management practices.

Experimental evidence of a symbiosis between red-cockaded woodpeckers and fungi

Primary cavity excavators, such as woodpeckers, are ecosystem engineers in many systems. Associations between cavity excavators and fungi have long been hypothesized to facilitate cavity excavation, but these relationships have not been experimentally verified. Fungi may help excavators by softening wood, while excavators may facilitate fungal dispersal. Here we demonstrate that excavators facilitate fungal dispersal and thus we report the first experimental evidence of a symbiosis between fungi and a cavity excavator, the red-cockaded woodpecker (RCW, Picoides borealis ). Swab samples of birds showed that RCWs carry fungal communities similar to those found in their completed excavations. A 26-month field experiment using human-made aseptically drilled excavations in live trees, half of which were inaccessible to RCWs, demonstrated that RCWs directly alter fungal colonization and community composition. Experimental excavations that were accessible to RCWs contained fungal communities similar to natural RCW excavations, whereas inaccessible experimental excavations contained significantly different fungal communities. Our work demonstrates a complex symbiosis between cavity excavators and communities of fungi, with implications for forest ecology, wildlife management, and conservation.

Habitat quantity of Red-cockaded Woodpecker Picoides borealis (Aves: Piciformes: Picidae) in its former historic landscape near the Big Thicket National Preserve, Texas, USA

<p>We quantified pine-forested habitat suitable for Red-cockaded Woodpecker <em>Picoides borealis</em> in the former historic range of the species to assess the potential for possible re-colonization. We used a remotely-sensed image and geographic information systems (GIS) to create a land-use/land (LU/LC) binary cover map, from which we calculated the habitat suitability index (HSI) based on an estimated home range of 50ha. A sensitivity analysis revealed the necessity for more data to make an accurate estimate, but our analysis of landscape metrics indicates more than 930ha of suitable habitat patches. These patches are heavily fragmented and mostly located on private lands. They can be assessed for understory and herbaceous vegetation and can be restored for possible re-establishment of approximately 18 groups/colonies of Red-cockaded Woodpeckers.</p><div> </div>

A model of gas mixing into single-entrance tree cavities during wildland fires

The level of protection to fauna provided by tree cavities during wildland fires is not well understood. Here we present a model for estimating the transport of combustion gases into cylindrical, single-entrance cavities during exposures caused by different wildland fire scenarios. In these shelters, the entrance occurs near the top of the cavity. This empirical model was developed from a suite of numerical experiments using the National Institute of Standards and Technology’s Fire Dynamics Simulator, which spanned a range of entrance diameters, wind speeds, gas temperatures, and vertical angles of incidence. To evaluate the model’s predictions, it was used to replicate, with great accuracy, a time series of carbon monoxide (CO) concentrations in a controlled experiment where a fabricated cylindrical cavity was exposed to combustion products. The time constant for cavity filling is proportional to the ratio of cavity volume to entrance area. Hot gases lead to significant stratification within the cavity during exposures. To demonstrate the model’s potential use in predicting faunal exposures in the context of land management, we show that the model can be used to estimate dosage within red-cockaded woodpecker (Picoides borealis Vieillot, 1809) cavities without requiring temporally detailed, local measurements of wind speed and combustion product concentrations.