Fig 1.
Red wolf recovery area (RWRA) in NENC showing federal and state-owned lands and land cover types [38].
Table 1.
Annual red wolf population size, COD and FU for collared, adult red wolves.
Table 2.
Red wolf fates by our classifications, 1987–2018 for 508 radio-collared adults.
The variable n (known fate subset) estimates the sum of known COD, and m (unknown subset) estimates the sum of FU and unknown COD. FU are those wolves who were radio-collared but were lost to USFWS monitoring. Legal COD was perfectly reported, all other CODs were not.
Fig 2.
Unknown fates can be estimated.
Observednon is the number of marked animals of known fate that died from nonhuman causes. Observedveh is the number of marked animals of known fate that died of vehicle collisions, and Observedpoa is the number of marked animals of known fate that died of poaching. Expectednon is the number of marked animals of unknown fate expected dead from nonhuman causes, Expectedveh is the number of marked animals of unknown fate expected dead from vehicle collision and Expectedpoa is the number of marked animals of unknown fate expected dead from poaching. P is the estimate of marked wolves dead from cryptic poaching. To account for the possibility of cryptic poaching with transmitter destruction before the wolf meets any other fate, we allocate m to the three imperfectly reported CODs. That is why the box for cryptic poaching appears above the others on the right side of the figure.
Table 3.
Equations used to estimate risk from nonhuman, vehicle and poached CODs.
Table 4.
Risk of legal, nonhuman and other human causes of death for known fates (n) and the unknown subset (m) using 3 cryptic poaching scenarios (P from Eqs 1A–1C).
Total poached is the sum of poached and cryptic poached. Other human is the sum of Vehicle and Total Poached (Table 4 in S1 File).
Fig 3.
Risk of poaching estimated with different methods from overlapping but different samples of years of the NENC red wolf population.
Treves [28] and this study presented 3 scenarios of cryptic poaching with a lower (open circle), middle (bar) and upper (closed circle) bound. Years of data vary by study [2, 10, 26, 47].
Fig 4.
Red wolf mortality each month (bars) compared to fate unknown (FU, black line).
FU are represented with a black line because there is more uncertainty with date of disappearance than with date of known deaths. Causes of death include legal, vehicle, poached, nonhuman, and unknown cause of death (COD) (Fig 4 in S1 File).
Fig 5.
Red wolf deaths and disappearances (FU) by cause during hunting season (dark gray) and non-hunting season (light gray). Hunting season is inclusive of all fall/winter hunting including white-tailed deer, black bear, and waterfowl (Fig 5 in S1 File).
Fig 6.
Days from collaring to death or disappearance (FU).
(Fig 6 in S1 File).