Temporal analysis of threats causing species endangerment in the United States

Abstract

Understanding temporal variation of threats that cause species endangerment is a key to understand conservation strategies needed to improve species recovery. We assessed temporal variation in the threats to species listed under the United States Endangered Species Act (ESA) as identified by the United States Fish and Wildlife Service (USFWS) and National Marine Fisheries Service (NMFS). Based on initial review of ESA listing decisions and literature, we identified six overarching threat categories: habitat modification, overutilization, pollution, species-species interaction, demographic stochasticity, and environmental stochasticity. We screened listing decision documents to determine threat occurrence (i.e., presence/absence of a given threat in a listing decision) for each threat category for all species listed between 1975 and 2017. We evaluated how the number of threats and specific threat occurrences changed over the past four decades. We found that the number of threats per listing decision increased more than twofold from an average of 1.5 (95% CI: 1.3-1.7) threats in 1975 to 3.7 (95% CI: 3.4-4.0) threats in 2017. Threat occurrence increased for habitat modification, environmental stochasticity and species-species interaction, while it decreased for overutilization since 1975 and for demographic stochasticity and pollution since the mid-2000s. The documented increase in number of threats at time of listing may be due to a growing human population exerting increased pressure on species persistence, improved scientific advancement in understanding factors influencing species endangerment, or prolonged time taken for more recent species to be listed under the ESA. We believe that key federal and state governmental regulations have resulted in a documented decrease in overutilization, demographic stochasticity, and pollution, and we recommend large-scale strategies combined with local planning efforts to address the growing threats of habitat loss, environmental stochasticity, and species-species interaction. K E Y W O R D SEndangered Species Act, environmental regulations, policy, temporal, threats Authors after Haines are listed in alphabetical order

Threats to Neglected Biodiversity: Conservation Success Requires More Than Charisma

“…We combined the majority of our 147 preliminary threats into these fine-resolution categories, but eliminated nine preliminary threats because they were too vague (Appendix 1). Leu et al (2019) had already examined temporal trends among broad-resolution threats, so no value would be added by including them in our analysis. In addition, we omitted five threats due to small sample sizes (representation in analyzed phyla) and/or because they did not fit into any of our categories (Appendix 1).…”

“…We recorded any threats facing the species from these sections if the threats were (1) affecting the species at the time of its listing (i.e., not historical threats) and (2) written with "certain, " not "potential" language. Refer to Leu et al (2019) for further details of threat language collection protocols.…”

Treatment of climate change in extinction risk assessments and recovery plans for threatened species

“…Considerable shortfalls exist in assessing climate change risks for currently listed species, in particular for species assessed longer ago. This trend over time is corroborated by research on listed threatened species in other jurisdictions; in Australia, less than 60% of recovery plans acknowledged climate change as a threat for species listed as threatened under the Environment Protection and Biodiversity Conservation Act, but the recognition of climate change as a threat increased over time (Hoeppner & Hughes, 2019), while in the United States, only 64% of species listed as endangered under the Endangered Species Act (ESA) had climate change considered as a threat, though the number of ESA documents mentioning climate change also increased over time (Delach et al, 2019; Leu et al, 2019). The increased prevalence of climate change as a threat in status reports is likely influenced by mounting evidence of the impact of climate change on wildlife species and their habitats (Pecl et al, 2017; Scheffers et al, 2016).…”

“…Threat identification is a critical part of the extinction risk assessment process as minimizing the impact of threats is necessary to achieve conservation objectives and species recovery (Lawler et al, 2002; Stewart et al, 2018). Recent reviews of legally listed threatened species identify habitat modification, overexploitation, pollution, and invasive species as top‐ranked threats with climate change ranked as a less important threat (Kearney et al, 2019; Leu et al, 2019; McCune et al, 2013). Furthermore, independent assessments of climate change vulnerability suggest that the importance of climate change is underestimated for species listed under the U.S.A.…”

Spatiotemporal patterns in Golden-cheeked Warbler breeding habitat quality and quantity

“…Habitat loss and degradation through anthropogenic landscape modification are major drivers of declining global wildlife populations and serve as primary threats justifying species’ listing under the United States Endangered Species Act (ESA; Hanski 2011, Bairlein 2016, Thompson et al 2016, Horváth et al 2019, Leu et al 2019). Habitat disturbances are even more notable for Neotropical migrant songbirds that travel long and costly distances between breeding and non-breeding sites.…”