Energetics and space use: intraspecific and interspecific comparisons of movements and home ranges of two Colubrid snakes

Abstract

Summary 1.Energy requirements explain substantial variation in movement and home range size among birds and mammals. This study assesses whether the same is true of snakes by comparing ratsnakes ( Elaphe obsoleta ) and racers ( Coluber constrictor ), ecologically similar species whose energy requirements appear to differ substantially (racers > ratsnakes). 2. Over 4 years 22 Elaphe and 16 Coluber were radio-tracked at the same site in Illinois to examine how movement and home ranges varied by sex and season. 3. Coluber moved more often and further per move than Elaphe , resulting in their estimated mean day range being almost four times larger than that of Elaphe (88·0 m day -1 vs. 23·1 m day -1). 4. Both male and female Elaphe moved more frequently early in the season consistent with matesearching, but mean distances moved did not differ seasonally or by sex. Both sexes of Coluber moved more later in the season and overall males moved further than females. 5. Interspecifically, patterns were consistent with the energetics hypothesis -Coluber had mean home ranges approximately four times larger than those of Elaphe . 6. Intraspecifically, increased movement did not always produce larger home ranges. Male Elaphe had larger home ranges than females despite not moving further, whereas male Coluber had comparable home ranges to females despite moving further. Also, Elaphe home ranges in Illinois were substantially smaller than has been documented in Ontario, despite Ontario Elaphe moving less. 7. Our results generally support the energetics hypothesis, but indicate that knowledge of ecology and energetics increases our understanding of area requirements beyond simple allometric predictions.

Habitat selection by grassland snakes at northern range limits: Implications for conservation

“…The maximum distance traveled by individuals in our study was up to 10 times farther than documented for populations further south (Hirth et al 1969, Brown and Parker 1976, Plummer and Congdon 1994, 1 exception: Moriarty and Linck 1997). In addition, home range sizes estimated for racers near the core of their range using similar MCP methods ranged from 1% to 17% the size of those in our study (Brown and Parker 1976, Plummer and Congdon 1994, Carfagno and Weatherhead 2008). Similarly, home range sizes of more southerly populations of Pituophis catenifer ranged from 2% to 39% the size of home ranges estimated for the bullsnakes we studied in Saskatchewan (Rodríguez‐Robles 2003, Kapfer et al 2008).…”

“…Larger home ranges have previously been recorded in northern populations of other snake species. For instance in Elaphe obsoleta obsoleta , home ranges were 3–4 times larger at the northern limit of their distribution compared to the core of their range in Illinois (Weatherhead and Hoysak 1989, Blouin‐Demers and Weatherhead 2002, Carfagno and Weatherhead 2008). This trend indicates that northern populations of snakes, especially those threatened with extinction because of human activities, likely need more protected land than their southern counterparts to accommodate their larger home ranges and longer movements.…”

Energy Costs of Catfish Space Use as Determined by Biotelemetry

“…Apparently, an increase in movement activity can be expected in the search for these resources [41]; however, these HR relocations can be energetically less demanding than the resources use itself [49]. Similarly, intensive movement does not always imply a large HR for an individual [50]. The aquatic environment allows fish to move with minimal energy expenditures; however, energy expenditures rapidly increases during active movement [33].…”

Sources of variation in the nesting success of understory tropical birds

“…In tropical Australia, however, weather related variables within a season explained little variation in snake activity patterns and feeding rates (Brown and Shine 2002). Studies of the thermal ecology of snakes using telemetry have revealed much about the factors that affect their encounter rates with nests in North America (Carfagno and Weatherhead 2006, 2008). We believe that similar studies of predator activity (snakes or otherwise) in tropical habitats offer opportunities to further understand temporal, spatial, and interspecific variation in rates of nest predation on birds.…”