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Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
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Black Ratsnake Class Presentation

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  • 1. The Importance of Body Size in Determining the Ecological Niche of the Black Rat Snake (Elapheobsoleta)<br />Denise M. Roth<br />
  • 2. So…Why study snakes??<br />http://www.larry-adams.com/snake-check.jpg<br />http://img114.imageshack.us/img114/8529/snake2tp9.jpg<br />http://www.he-man.org/cartoon/cmotu-pop/snakemen1.jpg<br />
  • 3. Snake populations are declining!<br />Habitat changes<br />Pet trade<br />Habitat fragmentation<br />Senseless killing<br />“Never wound a snake; kill it.” – Harriet Tubman<br />“If you see a snake, just kill it - don&amp;apos;t appoint a committee on snakes.” – Ross Perot<br />http://www.cartoonstock.com/newscartoons/cartoonists/tcr/lowres/tcrn210l.jpg<br />http://magickcanoe.com/snakes/baby-gartersnake-large.jpg<br />
  • 4. Changes in Habitat Use and Movement Patterns with Body Size in Black Ratsnakes (Elapheobsoleta)<br />Gabriel Blouin-Demers, Laura P. G. Bjorgan and Patrick J. Weatherhead<br />
  • 5. Question Addressed<br />Do black ratsnakes exhibit an ontogenetic niche shift?<br />In other words: Does body size influence movement patterns and use of habitat in black ratsnakes?<br />Hypothesis: <br />Juvenile black ratsnakes should move more often, move over longer distances and travel further from hibernacula.<br />
  • 6. Why does body size matter?<br />It influences thermoregulatory requirements<br />Habitat use<br />Susceptibility to predation<br />Diet<br />
  • 7. Black Ratsnake(Elapheobsoleta)<br />Adult length 3.5-8 ft<br />Hatchlings 11-16 in<br />Live in or near woodlands (near water)<br />Good climbers: competition for tree cavities<br />Diet: Rodents and bird eggs<br />Reproduce in early summer<br /> Oviparous- 12-20 eggs<br />Protected in neighboring states<br />Threatened in Canada<br />http://www.michigan.gov/dnr/0,1607,7-153-10370_12145_12201-61209--,00.html<br />
  • 8. Geographic Distribution<br />http://www.dlia.org/atbi/species/Animalia/Chordata/Reptilia/Squamata/Colubridae/Elaphe_obsoleta.shtml<br />
  • 9. Queen’s University Biological Station<br />Study area: 30 km² <br />~36 Snakes/ 1 km²<br />50 km north of Kingston, Ontario, Canada<br />100 km south of Ottawa, Ontario, Canada<br />http://www.dlia.org/atbi/species/Animalia/Chordata/Reptilia/Squamata/Colubridae/Elaphe_obsoleta.shtml<br />http://www.queensu.ca/biology/qubs/directions.html<br />
  • 10. Specimen Capture<br />Funnel traps<br />Measured for Snout-to-vent length (SVL)<br />Weighed<br />Sexed<br />Marked with a passive integrated transponder tag<br />http://icwdm.org/Images/amph-reptile/snake-nonpoison/Nonpoi10.jpg<br />
  • 11. Distinguishing between adult and juvenile<br />Juvenile<br />Adult<br />&amp;lt; 1050 mm SVL<br />http://animaldiversity.ummz.umich.edu/site/resources/usfws/juvratsnake.jpg/medium.jpg<br />http://www.tamssunshinehouse.com/Snakes/blackrat.jpg<br />
  • 12. Methods<br />Implanted specimens with radio-transmitters<br />Used movement data of adults from previous study (n = 82)<br />Additional 10 adults tracked<br />35 juveniles<br />Located snakes on foot and recorded location using GPS<br />Also recorded behavior observed<br />153 known juvenile locations<br />153 random locations<br />http://www.sciencedaily.com/releases/2007/07/070721200335.htm<br />
  • 13. Classification of Variables and Statistical Analysis<br />Analysis of Movement Patterns:<br />Mean distance from hibernacula during active season<br />Total distance travelled during active season<br />Number of times individual moved when relocated<br />Habitat Classification<br />Forest<br />Forest edge<br />Open habitat<br />MANOVA<br />Habitat selection based on the 23 structural variables<br />
  • 14. Results: Habitat Use<br />Juveniles utilized all available macrohabitats but preferred forest<br />No significant difference in microhabitat use between chosen and random locations<br />Key note:<br />If juveniles are in dispersal stage, they are potentially less selective for previously visited locations<br />n = 306<br />P = 0.11<br />
  • 15. Results: Movement PatternsDistance Travelled vs. SVL<br />All individuals followed at least 3 months during active period<br />ANCOVA:<br />Relationship between the total distance travelled and SVL<br />Significant with SVL<br />P = 0.002<br />No significant relationship with sex<br />P = 0.99<br />
  • 16. Results: Movement Frequency vs. SVL<br />Do smaller snakes move more often?<br />Relationship between SVL and number of times snake had moved<br />Significant relationship with sex<br />P &amp;lt; 0.001<br />Significant relationship with size<br />P = 0.04<br />
  • 17. Conclusion<br />Juveniles and adults differed in habitat use<br />Juveniles visited sites at random<br />Adults seemed to have preferred habitats and locations<br />Movement patterns and behavior varied with body size<br />Larger snakes moved further distances<br />Juveniles moved more often<br />
  • 18. Discussion<br />Possible explanations for habitat differences <br />Thermoregulation strategies<br />Juveniles escaping predation<br />Juvenile dispersal<br />
  • 19. Future Research<br />Ontogenetic niche shifts in reptiles<br />Juvenile dispersal stages?<br />Is it related to body size of the individual?<br />Study different land configuration<br />Where do the neonates go?<br />Does habitat fragmentation actually benefit the adults?<br />
  • 20. What this means for the black ratsnake<br /> Ontogenetic shifts in habitat use do not seem to play a major role in species survival at this time and conservation strategies should be focused elsewhere to have an impact in sustaining populations in Ontario, Canada.<br />
  • 21. References<br />Ohio Department of Natural Resources: Division of Wildlife. Eastern Ratsnake or Black Ratsnake. Accessed from http://www.dnr.state.oh.us/Home/species_a_to_z/SpeciesGuideIndex/blackeasternratsnake/tabid/6556/Default.aspx<br />http://www.washjeff.edu/Chartiers/Chartier/KEY/Reptiles/Snakes/brat.htm<br />http://www.ext.colostate.edu/PUBS/natres/06501.html<br />http://www.statistics.com/resources/glossary/a/ancova.php<br />Blouin-Demers, Gabriel, Bjorgan, Laura P. G. &amp; Weatherhead, Patrick J. (2007). Changes in Habitat Use and Movement Patterns with Body Size in Black Ratsnakes (Elapheobsoleta). Herpetologica, 63(4), 421-429.<br />Arendt, J. D., &amp;  Wilson, S. (1997). Optimistic growth: Competition and an ontogenetic niche-shift select for rapid growth in pumpkinseed sunfish (Lepomisgibbosus). Evolution, 51(6), 1946-1954.<br />Harding, James H. (1997). Amphibians and Reptiles of the Great Lakes Region. 308-312.<br />Michigan Department of Natural Resources. Black Rat Snake (Elapheobsoletaobsoleta). Accessed from http://www.michigan.gov/dnr/0,1607,7-153-10370_12145_12201-61209--,00.html<br />http://thinkexist.com/quotes/with/keyword/snake/<br />
  • 22. Questions<br />
  • 23. Description of Microhabitats<br />
  • 24. Distance from Hibernacula vs. Snout-to-Vent Length<br />
  • 25. Area of Home Range vs. SVL<br />
  • 26. Average ~ 65 snakes/ 1.8 km² (Blouin-Demers et. al 2002) <br />This study (Blouin-Demers et. al 2007) was 30 km² <br />Based on previous data: <br />Average in this study~1087 snakes/ 30 km ² or 36 snakes/1 km²<br />

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