Research Article
Ordinary Boldness or Parasitic Mind Control? A Case of Crocodile Nest-Raiding Raccoons in the Florida Keys
The protozoan parasite Toxoplasma gondii can alter behavior by heightening the boldness of multiple taxa to increase predation by their definitive host—Felids. We screened northern raccoons (Procyon lotor) for Toxoplasma-infection and monitored American crocodile (Crocodylus acutus) nests with camera traps in the Florida Keys, USA. On four occasions, we documented raccoons investigating a monitored active nest until the female crocodile chased them off. We quantified the elapsed reaction time (ERT) as the number of seconds between raccoon retreat and crocodile surfacing into the photo frame, with longer times representing faster responses of retreat prior to the crocodile attack. Three of the incidents resulted in ERTs of 4-8 seconds (mean = 6 seconds) before the crocodile surfaced. Yet, the radio-collared raccoon from our study had a 0 second ERT and narrowly escaped, which may be the result of chronic seropositive (titer = 1:200) and mind-altering effects of Toxoplasma beyond ordinary raccoon boldness. That individual successfully depredated a crocodile nest the following season. We hypothesize that Toxoplasma-infection is a Simpson’s paradox wherein short-term net benefits appear positive (e.g., successful nestpredation due to boldness), but overall they may result in lower fitness (e.g., lower survivorship due to boldness). Camera traps can elucidate behavioral changes in species interactions by explicitly quantifying reaction times.
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