RESUMEN
Monitoring of EEG, EKG and overt behavior of mink, muskrat, and beaver caught in leg hold traps in an aquatic tank, showed marked differences by species. Death by CO2 induced narcosis (submersion asphyxia) was evident in beaver, about 50 percent of muskrat but "wet" drowning occurred in mink. Bradycardia was evident in all three species but was most pronounced in the beaver. Times to cessation of struggle, brain activity and heart activity indicated that the terminal dives of mink and muskrat, but not beaver, fell within the tentative criteria of humaneness for trapping devices established by the Federal Provincial Committee for Humane Trapping of Canada.
Asunto(s)
Arvicolinae/fisiología , Bioética , Buceo , Ahogamiento/fisiopatología , Visón/fisiología , Política Pública , Roedores/fisiología , Animales , Canadá , Electroencefalografía , Frecuencia CardíacaRESUMEN
Seventeen-hundred terrestrial gastropods collected in central Maine were examined for Parelaphostrongylus tenuis and other nematodes. Prevalence of nematodes was 4 to 7% in most gastropod species, but was 19% in Pallifera spp. Cosmocercoides dukae and Rhabditis spp. were the most common nematodes recovered. Only four P. tenuis larvae (prevalence 0.1%) were found. Foci important for transmission of P. tenuis in Maine have not yet been found.
Asunto(s)
Moluscos/parasitología , Nematodos , Animales , MaineRESUMEN
1. Implanted ECG transmitters were used to determine heart rates for several activities of beaver (Castor canadensis), mink (Mustela vison), and muskrat (Ondatra zibethicus) under free-ranging laboratory conditions within an aquatic tank. 2. All three species exhibited bradycardia when diving but mink heart rates returned to pre-dive levels if the dive lasted greater than 30 sec. 3. Heart rates for all other behaviours were significantly (P less than 0.05) higher than for diving and averaged about 120/min (beaver), 265/min (mink) and 240/min (muskrat). 4. Mink heart rate values were higher than would be expected based on general energetic equations if we assume heart rate to be reflective of energy costs. This was considered to be a function of this species' fusiform body shape.
Asunto(s)
Adaptación Fisiológica , Frecuencia Cardíaca , Animales , Arvicolinae , Buceo , Visón , Roedores , Factores de TiempoRESUMEN
1. Heart rates of beaver (Castor canadensis) under free-ranging captive conditions for active behaviors and resting in water (approximately 121 beats/min) were significantly (P less than 0.01) higher than for resting on land (100 beats/min). 2. Although no transient recovery tachycardia was evident in swimming heart rates following diving, average swimming heart rates were higher (127 beats/min) after diving than after other precursor behaviors (123 beats/min). 3. Beaver exhibited bradycardia when sleeping (75 beats/min), diving (61 beats/min), and when threatened on land (57 beats/min). 4. The respiratory sinus arrhythmia indicated a respiratory rate of 15 breaths/min. 5. Cold temperatures (approximately 0 degree C) elicited higher heart rates than did warmer temperatures (approximately 20 degrees C) in active, non-diving behaviors (P less than 0.05).