May 2013 update on the SNAMP Fisher Team
The SNAMP fisher team currently has 32 fisher (18 females and 14 males) under collar and 11 females are currently denning. The SNAMP project has collared a total of 109 fishers during the research project: 62 females and 47 males.
Den tree location: In April, the field crew transitioned from the trapping season to the denning season. As collared females are found to be settling in on their chosen den areas by aerial telemetry, the field crew begins using ground telemetry to locate their individual den trees. Finding den trees is a tricky business. Imagine standing alone in the forest among a cluster of trees, with a GPS location taken from several thousand feet above and whose error may be over 300 meters, looking for the home of an animal which may not be home at all but off foraging instead.
When the crew does find the den tree, three cameras are placed around it to confirm the female’s presence and/or any kit movement. Keep in mind that the females will move to a new tree with their kit(s) several times over the next two months multiplying the difficulty of keeping track of the den trees of any one female, let alone 18. Between March 23rd and April the team located seven den trees from the 18 females fisher currently being tracked. They confirmed the first kit for the 2013 season on April 1st as it was moved from its natal tree to its first maternal tree by its mother.
Camera surveys: The before and after camera surveys of the key research watersheds for presence or absence of fisher continues until August of 2013 in 134 grids of a square kilometer each. The area includes five different fuel treatment projects. Fisher use of these areas is nearly as high this year as last and has run between 57% and 76% over all 6 yrs.
Carcass retrieval: The team continues to collect fisher carcasses for future autopsy. We have retrieved 8 fisher mortalities so far in 2013, all have been males. Between April 2012 and March 31, 2013 (year 6 of the project) there were a total of 11 deaths, 5 females and 6 males. Four died of predation, 1 by road kill, and 6 are from unknown causes. SNAMP has recorded a total of 54 mortalities during the study period.
The survival rate in the SNAMP area for females in year 6 was 82%. Female survival has been over 80% every year except 2010 with a 5 year average of 79%. Survival rates for males have been consistently lower in all age classes.
Crew Staffing: As a result of the increased work created by so many denning females, the team hired two additional crew members, bringing the total to five. This will allow them to keep up with the denning work as well as continued camera survey work in the key watersheds in and around the Sugar Pine fuels treatment, looking for the presence or absence of fisher.
Manuscripts: Two manuscripts including contributions and data from SNAMP Fisher were submitted for peer-reviewed publication during this reporting period: 1) Intraguild predation on fishers in California: patterns of predation by three larger carnivores. Submitted to Journal of Wildlife Management and Wildlife Monographs”. 2) Impacts of rodenticide and insecticide toxicants from marijuana cultivation sites of fisher survival rates in the Sierra National Forest, California. Submitted to Conservation Letters.
Another manuscript was accepted for publication: 1) An evaluation of a weaning index for wild fishers (Martes pennanti) in California. In press. Journal of Mammalogy.
Presentations: Fisher presentations were made at the Western Section of the Wildlife Society meeting, the California Martes Working Group as well as an Audubon meeting in Oakhurst. Work continues in the Southern Sierra Fisher Working Group as well as the Culvert and Vehicle Collision project.