Bobcat, Coyote, and Gray Fox
Bobcats and coyotes were captured using modified No's. 1 ½ and 3 Victor coil spring soft- catch foot-hold traps (Woodstream Corporation, Lititz, Pennsylvania, USA). Gray fox were targeted using No. 1 ½ and captured incidentally in No. 3 traps. Number 3 traps were periodically modified with an extra set of coil springs (beefer springs) to increase holding power of the trap. Each trap was equipped with a 12 cm chain, a shock spring, and swivel to reduce injury to captured animals. Traps were anchored with 1.8 cm × 61 cm or 91 cm rebar stakes and cross staked (double staked) when deemed necessary. We did not use drags during the study.
Prior to the trapping period (January-March), the study area was scouted for bobcat, coyote, and gray fox sign (tracks, scat, caches, etc) to increase trapping efficiency. We trapped primarily along U.S.D.A. Forest Service roads, as well as on fire lines, logging roads, creek bottoms, and habitat edges.
Five types of trap sets were used to capture bobcats, coyotes, and gray foxes: blind, dirt hole, scent post, scat, and baited. At most sets, trap placement was species-specific. We generally placed traps approximately 4-7 inches from the attractant to capture gray fox; 5-8 inches for bobcats; and 12 - 24 inches for coyotes. Additionally, stones, twigs, or other objects were usually used to guide the respective animal's steps. In all sets, special attention was given to carefully blend the trap with the surrounding substrate.
At blind sets, we used no scents, lures, or baits to attract animals. A dirt hole consisted of placing a single trap in front of hole, or multiple holes, in which lure or bait was placed. All holes were dug at 45-90 at varying depths. A scent post consisted of applying bobcat, coyote, or gray fox urine or call lure on a log or clump of grass. We then placed a trap in the most likely path an animal would use to investigate the scent. A scat set was a single trap placed directly next to a single scat, or multiple scats (toilet); the scat and/or area directly adjacent to the trap was the sprayed with urine of the targeted species. A baited set consisted of a single or multiple traps placed around the bait. Beaver, white-tailed deer, or rabbit were frequently used as baits. We checked all traps at least once daily, usually immediately after sunrise, to minimize time captured animals spent in the trap.
Raccoon and Opossum
Raccoons and opossums were targeted using wire cage traps and captured incidentally in foot-hold traps. Traps were baited with a variety of canned fish (sardines and jack mackerel), fish scraps, jellies (grape and apple), and/or pastries to maximize capture success. We used debris or vegetation around the trap site to cover and conceal traps. Traps were usually placed in areas with abundant sign or at sites raccoons and opossums were likely to frequent (creek banks, habitat edges, logging roads). All traps were checked at least once daily, usually immediately after sunrise. Captured animals were transported to the area headquarters for processing.
Bobcats were netted and restrained using an intramuscular injection Ketamine hydrochloride (Ketaset, Veterinary Products, Fort Dodge Laboratories, Fort Dodge, Iowa, USA) at approximately 15 mg/kg of estimated body mass. Raccoons were restrained using an intramuscular injection of Ketamine hydrochloride at approximately 10 mg/kg of estimated body mass. Coyotes, gray fox, and opossums were restrained using electrical tape around the rostrum and legs. Once immobilized, all animals were aged (juvenile, adult), weighed, standard morphological measurements were taken, and each was given a unique ear tattoo. We noted the condition of the trapped foot and if necessary, applied an antibiotic ointment to help prevent infection if a wound was present. Adult bobcats and coyotes were then fitted with a 175-225 g mortality or motion-sensitive radiotransmitter (Advanced Male Coyote Being Ear TattooedTelemetry Systems, Isanti, Minnesota, USA; Wildlife Materials, Carbondale, Illinois, USA). Adult gray fox and raccoons were fitted with 100-125 g mortality or motion-sensitive radiotransmitters. Adult opossums were fitted with 50-60 g mortality-sensitive radiotransmitters. Transmitter frequencies ranged between 150-152 MHz. We maintained bobcats and raccoons overnight in portable pet kennels to ensure recovery and subsequently released each animal at its respective capture site the following morning. Coyotes, gray fox, and opossums were released immediately following processing.