Effects of snake fungal disease on short‐term survival, behavior, and movement in free‐ranging snakes

Abstract

Pathogenic fungi are increasingly associated with epidemics in wildlife populations. Snake fungal disease (SFD, also referred to as Ophidiomycosis) is an emerging threat to snakes, taxa that are elusive and difficult to sample. Thus, assessments of the effects of SFD on populations have rarely occurred. We used a field technique to enhance detection, Passive Integrated Transponder (PIT) telemetry, and a multi‐state capture–mark–recapture model to assess SFD effects on short‐term (within‐season) survival, movement, and surface activity of two wild snake species, Regina septemvittata (Queensnake) and Nerodia sipedon (Common Watersnake). We were unable to detect an effect of disease state on short‐term survival for either species. However, we estimated Bayesian posterior probabilities of >0.99 that R. septemvittata with SFD spent more time surface‐active and were less likely to permanently emigrate from the study area. We also estimated probabilities of 0.98 and 0.87 that temporary immigration and temporary emigration rates, respectively, were lower in diseased R. septemvittata. We found evidence of elevated surface activity and lower temporary immigration rates in diseased N. sipedon, with estimated probabilities of 0.89, and found considerably less support for differences in permanent or temporary emigration rates. This study is the first to yield estimates for key demographic and behavioral parameters (survival, emigration, surface activity) of snakes in wild populations afflicted with SFD. Given the increase in surface activity of diseased snakes, future surveys of snake populations could benefit from exploring longer‐term demographic consequences of SFD and recognize that disease prevalence in surface‐active animals may exceed that of the population as a whole.

The impact of PIT tags on the growth and survival of pythons is insignificant in randomised controlled trial

“…Furthermore, the degree to which PIT tagging impacts the health, behaviour, or welfare of pythons is unknown, despite evidence suggesting the impacts of PIT tagging in other taxa are minimal ( Ombredane, Bagliniere & Marchand, 1998 ; Ott & Scott, 1999 ). It is therefore important to determine if there are any significant negative impacts of PIT tagging on the growth or survival of pythons before this identification technique is adopted, or to ensure it is appropriate, for the study or tracking of pythons in captive facilities or ecological studies ( Leuenberger et al, 2019 ; Lind, McCoy & Farrell, 2018 ; McKenzie et al, 2021 ).…”

Host traits and environment interact to determine persistence of bat populations impacted by white‐nose syndrome

“…Furthermore, free-flying bats in both persisting sites had higher late hibernation body masses, and this was more pronounced in Persisting 1 (Cold + Dry). Behavioural responses that moderate the severity of disease have also been proposed for snake populations impacted by snake fungal disease (McKenzie et al, 2021), caused by the fungal pathogen Ophidiomyces ophiodiicola (Lorch et al, 2015). Snakes infected with O. ophiodiicola exhibit changes to their behaviour that include increased surface activity and more time spent in exposed environments compared to their disease-free conspecifics (Lorch et al, 2015;McKenzie et al, 2021), potentially a sign of a behavioural fever response to infection (Burns et al, 1996).…”

Host traits and environment interact to drive host-pathogen coexistence following pathogen invasion

“…Furthermore, free-flying bats in both persisting sites had higher late hibernation body masses, and this was more pronounced in Persisting 1 (Cold + Dry). Behavioral responses that moderate the severity of disease have also been proposed for snake populations impacted by snake fungal disease 99 , caused by the fungal pathogen Ophidiomyces ophiodiicola 100 . Snakes infected with O. ophiodiicola exhibit changes to their behavior that include increased surface activity and more time spent in exposed environments compared to their disease-free conspecifics 99,100 , potentially a sign of a behavioral fever response to infection 101 .…”

“…Behavioral responses that moderate the severity of disease have also been proposed for snake populations impacted by snake fungal disease 99 , caused by the fungal pathogen Ophidiomyces ophiodiicola 100 . Snakes infected with O. ophiodiicola exhibit changes to their behavior that include increased surface activity and more time spent in exposed environments compared to their disease-free conspecifics 99,100 , potentially a sign of a behavioral fever response to infection 101 . However, we make the important distinction here that because movement within hibernacula was observed in bats prior to the WNS epidemic, this behavior may have been pre-adaptive to surviving the disease rather than a direct response to the disease itself.…”