The Importance of Body Size in Determining the Ecological Niche of the Black Rat Snake (Elapheobsoleta)<br />Denise M. Rot...
So…Why study snakes??<br />http://www.larry-adams.com/snake-check.jpg<br />http://img114.imageshack.us/img114/8529/snake2t...
Snake populations are declining!<br />Habitat changes<br />Pet trade<br />Habitat fragmentation<br />Senseless killing<br ...
Changes in Habitat Use and Movement Patterns with Body Size in Black Ratsnakes (Elapheobsoleta)<br />Gabriel Blouin-Demers...
Question Addressed<br />Do black ratsnakes exhibit an ontogenetic niche shift?<br />In other words: Does body size influen...
Why does body size matter?<br />It influences thermoregulatory requirements<br />Habitat use<br />Susceptibility to predat...
Black Ratsnake(Elapheobsoleta)<br />Adult  length 3.5-8 ft<br />Hatchlings 11-16 in<br />Live in or near woodlands (near w...
Geographic Distribution<br />http://www.dlia.org/atbi/species/Animalia/Chordata/Reptilia/Squamata/Colubridae/Elaphe_obsole...
Queen’s University Biological Station<br />Study area: 30 km² <br />~36 Snakes/ 1 km²<br />50 km north of Kingston, Ontari...
Specimen Capture<br />Funnel traps<br />Measured for Snout-to-vent length (SVL)<br />Weighed<br />Sexed<br />Marked with a...
Distinguishing between adult and juvenile<br />Juvenile<br />Adult<br />&lt; 1050 mm SVL<br />http://animaldiversity.ummz....
Methods<br />Implanted specimens with radio-transmitters<br />Used movement data of adults from previous study (n = 82)<br...
Classification of Variables and Statistical Analysis<br />Analysis of Movement Patterns:<br />Mean distance from hibernacu...
Results: Habitat Use<br />Juveniles utilized all available macrohabitats but preferred forest<br />No significant differen...
Results: Movement PatternsDistance Travelled vs. SVL<br />All individuals followed at least 3 months during active period<...
Results: Movement Frequency vs. SVL<br />Do smaller snakes move more often?<br />Relationship between SVL and number of ti...
Conclusion<br />Juveniles and adults differed in habitat use<br />Juveniles  visited sites at random<br />Adults seemed to...
Discussion<br />Possible explanations for habitat differences <br />Thermoregulation strategies<br />Juveniles escaping pr...
Future Research<br />Ontogenetic niche shifts in reptiles<br />Juvenile dispersal stages?<br />Is it related to body size ...
What this means for the black ratsnake<br />    Ontogenetic shifts in habitat use do not seem to play a major role in spec...
References<br />Ohio Department of Natural Resources: Division of Wildlife. Eastern Ratsnake or Black Ratsnake. Accessed f...
Questions<br />
Description of Microhabitats<br />
Distance from Hibernacula vs. Snout-to-Vent Length<br />
Area of Home Range vs. SVL<br />
Average ~ 65 snakes/ 1.8 km² (Blouin-Demers et. al 2002) <br />This study (Blouin-Demers et. al 2007) was 30 km²   <br />B...
Upcoming SlideShare
Loading in …5
×

Black Ratsnake Class Presentation

1,538 views
1,364 views

Published on

0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
1,538
On SlideShare
0
From Embeds
0
Number of Embeds
5
Actions
Shares
0
Downloads
0
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Black Ratsnake Class Presentation

  1. 1. The Importance of Body Size in Determining the Ecological Niche of the Black Rat Snake (Elapheobsoleta)<br />Denise M. Roth<br />
  2. 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. 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&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. 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. 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. 6. Why does body size matter?<br />It influences thermoregulatory requirements<br />Habitat use<br />Susceptibility to predation<br />Diet<br />
  7. 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. 8. Geographic Distribution<br />http://www.dlia.org/atbi/species/Animalia/Chordata/Reptilia/Squamata/Colubridae/Elaphe_obsoleta.shtml<br />
  9. 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. 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. 11. Distinguishing between adult and juvenile<br />Juvenile<br />Adult<br />&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. 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. 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. 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. 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. 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 &lt; 0.001<br />Significant relationship with size<br />P = 0.04<br />
  17. 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. 18. Discussion<br />Possible explanations for habitat differences <br />Thermoregulation strategies<br />Juveniles escaping predation<br />Juvenile dispersal<br />
  19. 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. 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. 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. & 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., &  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. 22. Questions<br />
  23. 23. Description of Microhabitats<br />
  24. 24. Distance from Hibernacula vs. Snout-to-Vent Length<br />
  25. 25. Area of Home Range vs. SVL<br />
  26. 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 />

×