Defenders of Wildlife v. Ryan Zinke, 2017 U.S. App. LEXIS 3825

Background

The Northern Rocky Mountain gray wolf was delisted in Wyoming by the Fish and Wildlife Service (the Rule, 77 Fed. Reg. 55,530 (2012)) after finding recovery goals met (≥30 breeding pairs/300 wolves regionwide; state minima 10 breeding pairs/100 wolves on state lands) and relying on Wyoming’s revised statutes, regulations, and non‑binding management plan (and Addendum) committing to maintain a population buffer above minima.
Environmental groups challenged the Rule; the district court vacated it solely on the ground that Wyoming’s Addendum buffer commitment was non‑binding and thus Wyoming lacked adequate “regulatory mechanisms” under the Endangered Species Act (ESA), 16 U.S.C. § 1533(a)(1)(D).
The Secretary and Wyoming appealed; environmental groups cross‑appealed on genetic‑connectivity findings and the Service’s conclusion that Wyoming’s unregulated predator area is not a “significant portion” of the species’ range.
The D.C. Circuit applied Chevron deference to the Service’s interpretation of “regulatory mechanisms,” reviewed the administrative record for arbitrariness under the APA, and evaluated scientific studies on dispersal and genetics (e.g., vonHoldt, Jimenez) and state incentives/regulatory text.
The court reversed the district court’s vacatur (holding the Service reasonably relied on Wyoming’s management plan/commitments as sufficiently certain and aligned with state incentives) and otherwise affirmed the Rule, rejecting the cross‑appeal challenges on genetic connectivity and significant‑portion grounds.

Issues

Issue	Plaintiff's Argument	Defendant's Argument	Held
Adequacy of "regulatory mechanisms" under ESA §4(a)(1)(D) — must commitments be legally binding?	The Service’s reliance on Wyoming’s non‑binding Addendum and management plan is insufficient; regulatory mechanisms must be legally enforceable.	"Regulatory mechanisms" is ambiguous; Service permissibly considered non‑binding but sufficiently certain state management commitments and statutory incentives to maintain a buffer.	The Service reasonably relied on Wyoming’s plan and incentives; non‑binding commitments can be part of regulatory mechanisms under Chevron.
Whether the Rule arbitrarily ignored need to regulate human‑caused mortality (buffer vs. binding regulation)	Service required an ‘‘adequately regulated’’ buffer; non‑binding plan does not ensure mortality control.	Wyoming statutes/regulations set mandatory minima and permit rules (suspension if minima could be compromised); combined with state incentives, buffer is practically enforceable.	Service’s reading is reasonable; statutory/regulatory scheme plus plan and incentives suffice; preamble and monitoring/emergency ESA provisions support delisting.
Genetic connectivity — whether effective migrants ≥1 per generation and whether reliance on studies was arbitrary	Studies show effective migrant rate below 1 per generation; delisting risks future genetic isolation.	Studies undercount migrants (limited sampling); Service reasonably extrapolated and relied on additional measures (monitoring, quota adjustments, possible translocation) if needed.	Service’s reliance on available studies and projections was within its expertise and not arbitrary; contingencies and monitoring mitigate risk.
"Significant portion of range" — is Wyoming predator area significant because wolves can be killed without restriction?	The predator area’s unregulated killing threatens the population and genetic exchange; it is a significant portion of range.	Predator area contains little suitable habitat, few breeding pairs, and even if lost would not render species endangered; migrants can disperse via other routes.	Service reasonably concluded the predator area is not a "significant portion" under its interpretation (a portion whose loss would threaten species).

Key Cases Cited

Defenders of Wildlife v. Jewell, 815 F.3d 1 (D.C. Cir. 2016) (upholding Service reliance on state management commitments where sufficiently certain)
In re Polar Bear Endangered Species Act Listing & Tailoring Rules, 709 F.3d 1 (D.C. Cir. 2013) (interpretation of "regulatory mechanisms" and deference to agency scientific judgment)
American Wildlands v. Kempthorne, 530 F.3d 991 (D.C. Cir. 2008) (standard of review for agency rulemaking under APA)
Motor Vehicle Mfrs. Ass'n v. State Farm Mut. Auto. Ins. Co., 463 U.S. 29 (U.S. 1983) (arbitrary and capricious standard for agency action)
Kennecott Utah Copper Corp. v. U.S. Dep't of Interior, 88 F.3d 1191 (D.C. Cir. 1996) (preamble language can carry legal weight)
All. for the Wild Rockies v. Salazar, 672 F.3d 1170 (9th Cir. 2012) (background on prior delisting litigation for wolves)
Friends of Blackwater v. Salazar, 691 F.3d 428 (D.C. Cir. 2012) (deference to agency expertise in ESA context)
Greater Yellowstone Coal., Inc. v. Servheen, 665 F.3d 1015 (9th Cir. 2011) (agency regulation of wolf take and implications for management)
Trout Unlimited v. Lohn, 559 F.3d 946 (9th Cir. 2009) (consideration of artificial propagation/translocation in listing decisions)