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

To forestall the current rate of global extinction, we need to identify strategies that successfully recover species. In the last decade, the recovery record for the United States Endangered Species Act (ESA) has improved. Our aim was to review federal delisting documents for recovered species and quantify patterns in taxonomy, history of threats, policy, funding and actions that are associated with species recovery. In comparison to species still listed, the average recovered species was a vertebrate, had been listed longer under the ESA, was exposed to a lower number of threats at the time of listing, and received relatively higher levels of funding. Based on our review, we suggest the following strategies to improve species recovery: provide more time for ESA protection, allocate more funding for recovery, maintain environmental regulations that facilitate recovery, establish more private landowner agreements, and increase the area of protected lands.

With species increasingly imperiled due to anthropogenic activities, conservation practitioners are tasked with determining conservation priorities to make the best use of limited resources. One way of setting priorities is to categorize species based on risk of extinction. The United States' Endangered Species Act (ESA) has two listing statuses into which imperiled species are placed to receive protections: threatened or endangered. Our objective was to identify differences between threatened and endangered (T&E) species beyond what is outlined in their ESA definitions. For 6 broad-resolution threats (habitat modification, overutilization, pollution, species-species interactions, environmental stochasticity, and demographic stochasticity), we investigated whether there is a difference in the number and types of threats which impacted T&E species at the time of their listing. We found that threatened (x̄= 2.9, SD = 1.4) and endangered (x̄= 3.0, SD = 1.1) species faced a similar number of threats at time of their listing. The only broad-resolution threat that impacted endangered species more than threatened species was demographic stochasticity, with endangered species being 2.1 times (95% CI = 1.5-2.8) more likely to be impacted than threatened species. We examined demographic stochasticity by breaking it down into finerresolution threats to identify additional differences between