Snake Populations and Human Intervention - Essay Example

www.academia-research.com Sumanta Sanyal d: 24/10/06 Research Proposal: Snake Populations and Human Intervention Abstract The research proposes to disprove the following general hypothesis. Hypothesis: "Snake populations in a particular region remain relatively unaffected by human intervention." For the research purpose human intervention is being considered as harmful. The chosen snake is the relatively rare Timber rattlesnake (Crotalus horridus) found in some counties of West Virginia, USA. This particular species is chosen because it is known to be highly sensitive to negative human impact. Detrimental or harmful intervention is construed here as any human measures that actually do or have the potential to kill, seriously maim or injure adult and baby snakes or destroy eggs and habitat. Two areas of similar size, one where the snakes are conserved (Monongahela National Forest, West Virginia) and one where they are subjected to one or more harmful human influence (County Mercer or Mingo of West Virginia) shall be identified. Both areas are known C. horridus habitats. Snake population sizes shall be determined for both areas from local reports of spottings in summer. Adults, young ones and neonates shall all be considered for the study. The two population sizes shall be compared. The population size from the conserved area shall serve as the control as there is supposedly no human intervention and the snakes are left in their pristine state. If the population size from the non-conserved area is larger than or the same as that from the conserved area it will be construed that the hypothesis is correct. If the converse is true the hypothesis will be proved wrong and this research study shall be considered successful. The entire study will be supplemented by a questionnaire that shall be presented to locals residing near the two survey areas. The questionnaire design will be such that information on the respondents' awareness of conservation efforts and their attitude towards the snakes can be judged. This, together with the study results can help immensely in future studies conducted to assess how snakes can co-habit with humans without friction. Introduction Features of Crotalus horridus are discussed hereafter. Only those features that are germane to the population study this paper is a research proposal to are being discussed for compression of details. Taxonomy: The timber rattlesnake is a member of the almost worldwide family Viperidae. These viperids include both Old World and New World snakes that have existed since the Miocene Age (Adams, Jennifer P., 2005). Crotalinae, commonly called pit-vipers, is a sub-family comprised of 16 genera and 144 species (Adams, Jennifer P., 2005). Crotalinae members are characterized by two pitted heat sensors between the eyes and nares, hollow retractable fangs, a single row of sub-caudal scales and vertical pupils (Adams, Jennifer P., 2005). There are 33 Crotalus New World species and sub-species, of which 25 inhabit North America. The rattle and the broad head narrowing at the neck and descending into a thick heavy body most characterize this genus (Adams, Jennifer P., 2005). Distribution and Status Distribution: Timber rattlesnakes range widely from New Hampshire south to Florida, west to Texas and north again to southeast Nebraska through to southeast Minnesota (Fig. 1, Appendix) (Staff, CRACM, 2003). Despite this wide distribution timber rattlesnakes are usually found in isolated pockets to the western and northern limits of their ranges. In particular context to West Virginia, where this study will be conducted, the species ranges from the eastern panhandle through the Alleghenies south to Mingo and Mercer counties (Fig. 2, Appendix) (West Virginia Snakes, 2003). Status: Evolutionary trends have produced Crotalus horridus as a 'long-lived, slow-reproducing species with a low annual recruitment rate and slow population turnover' (Brown, William S., et al, 1994). In pristine habitats, the species has few enemies and varying annual weather patterns that influence availability of reproductive females primarily causes fluctuations in populations. Though the species is long-lived, reportedly 25-30 years in West Virginia, members mature late, at 8-12 years for females and a year or two less for males, and the litter is small. Hatchlings come out in late summer. Litter size may be as few as one and never more than eight or nine. Survival rates among young are low. The females are ready to reproduce only after a period of 3-4 years. The young mature by 3-4 years. The low reproductive capability is often impeded by weather patterns (Adams and Garst, Undated). All these factors make this species extremely vulnerable to negative human impact. Population sizes do not recover easily after any manner of depredation. Two factors, together with their lifelong fidelity to a den in large numbers, are responsible for population declines reported from states these snakes range in. Human Factor: Human factors include habitat loss due to development, habitat degradation and extirpation during unnecessary round-ups and hunts and collection patterns when they are caught to be sold or kept as pets or for commercial purposes (Adams and Garst, Undated). Biological Factors: The species' reproductive capabilities are influenced by weather patterns. In bad years the recruitment rate may fall to levels that may take several good years to recover. Continuing decline in populations has caused several states to place them on endangered/threatened species' lists. In a number of states, as in (Maine, Rhode Island) they are already extinct (Brown, William S., et al, 1994). In others, New Hampshire (Brown, William S., et al, 1994), they are seriously endangered. Nevertheless, though experts unanimously agree that the timber rattlesnake is seriously imperiled throughout its range, it is opined that federal protection cannot be afforded as it is large and highly venomous (Staff, CRACM, 2003). It is also noteworthy that though timber rattler populations are on the decline as elsewhere the species is not listed in West Virginia. Ecology Habitat: The habitat preference of the timber rattlesnake is much influenced by its reproductive condition. Though the species is generally associated with eastern deciduous or mixed deciduous/coniferous forests on mountainous terrain, as is true for West Virginia inhabitants, its wide geographic distribution implies that its habitat preferences are highly influenced by local flora and geographic features. Thus, habitat varies locally in this species (Staff, CRACM, 2003). The snake's microhabitat has three elements that vary with season, including the breeding one - overwinter dens, rookeries and summer ranges (Adams, Jennifer P., 2005). Non-gravid snakes never leave the forest canopy while gravid females tend to use the sunshine in more open territory such as sparsely forested areas and rock crops. Some of these females have been known to use hollow logs in these open areas to exploit optimal environmental conditions such as warmth, humidity and a stable micro-climate that can assist maximally in embryo development and gestation (Staff, CRACM, 2003). Age also influences habitat choice. Juvenile snakes, more than adults, prefer covered areas such as tree canopies and logs, shrubs or woody debris. Juveniles have also been known to stay up in trees for extensive periods (Staff, CRACM, 2003). Hibernation and Denning: The species is highly dependent upon winter denning facilities. It usually prefers cracks and fissures in rocks or talus and scree slopes. In the absence of that it may use streambeds or any other feature where exposed rock with cracks and fissures is available. This may be steep slopes where erosion has exposed the underlying bedrock layer (Staff, CRACM, 2003). The principal requirements seem to be relative warmth and absence of water and snow, aside from protection from predatory species. Hibernation begins in early fall, late September or early mid-October, and egress in spring is by late April or early May (Staff, CRACM, 2003). The hibernation period for timber rattlers that live at higher elevations or farther up north is much greater (earlier ingress and later egress) than for those that live at lower elevations or farther down south (Staff, CRACM, 2003). Denning is communal and in some areas a host of snakes will utilize the same den. Historical reports from the east have featured 100-200 snakes at one den. Recently, these numbers have lessened much. Another interesting fact to this species is that the members are faithful to dens, often for a lifetime. Walker (2000) and Gibson (2003) (Source: Staff, CRACM, 2003) have found that this fidelity rate for snakes tracked for consecutive years in Indiana was 100%. This singular habit also endangers the snakes as intelligent predators like humans know easily where they may be regularly found, in large numbers, and often extirpate all incumbents by destroying one single den. Morphology As already expressed in the introduction to this proposal, only those morphological features of Crotalus horridus that are of specific interest to the research study are being discussed hereafter. Color: Crotalus horridus has four distinct color morphs ranging from the western to southern varieties and including the two eastern varieties. The eastern varieties have the yellow and black morphs. These are determined by the dorsal-lateral head color. The yellow morph is identified by a yellow or tan head with a light yellow chin, often with brown flecks, and yellow neck and ventrum (Adams, Jennifer P., 2005). The black morph has a black or gray head with a white chin (with black flecks) and white neck and ventrum (Adams, Jennifer P., 2005). The heads of both morphs are unmarked but the body colors may vary widely from yellow, black, gray to brown and the tail is black. The members have chevron-shaped dorsal crossbands bordered by lighter colors creating contrast between cross-bands and body colors (Adams, Jennifer P., 2005). Size: Size may vary from 1.5 m to maximum 1.8 m. The species is sexually dimorphic with males being larger than females (Adams, Jennifer P., 2005). Neonates average 25.4-33.0 cm in size at birth. The first molt occurs at 8 to 10 days. Thereafter snakes molt once or twice a year (Adams, Jennifer P., 2005). Predatory Habits: Crotalus horridus is a model ambush predator that coils in wait behind some suitable camouflage spot like a log. The snake's unique coloration makes it blend with the dark colors of its forest environment. It can thermally, chemically and visually track approaching prey. It strikes and stalks prey till its venom has done its work and the prey is helpless. Adults prey upon small mammals such as sciurids, murids, dipodids, leporids and soricids (Adams, Jennifer P., 2005) although meals are not restricted to these taxa alone. It is reported that neonates are capable of trailing and striking at prey adults take but they are restricted in choice by size (Adams, Jennifer P., 2005). Subjective Predation: Timber rattlers are subject to predation from a large body of animals such as hawks, owls, coyotes and skunks (Adams, Jennifer P., 2005) though others such as black racers, wild turkeys and white-tailed deer (Adams, Jennifer P., 2005) also make inroads into populations. Humans are also serious predators to this species. Neonates are more susceptible to predation than adults. Neonates are also subject to high mortality rates because of lack of suitable-size prey and lack of hibernacula (Adams, Jennifer P., 2005). Methodology The research study will utilize this subsequent methodology to disprove the hypothesis: "Snake populations in a particular region remain relatively unaffected by human intervention." Though Crotalus horridus is highly sensitive to any manner of pervasive predation, as is possible with humans, because of its extremely low reproductive capabilities, chiefly, it is still a snake that can be construed to be a true specimen of suborder Serpentes. Thus, any negative human impact on this species can be construed as being negative for all members of the suborder. This is especially true for member species inhabiting North America since most of these share common characteristics with other members of the suborder existing elsewhere. West Virginia: The choice of West Virginia as the test site is because the state has a relatively high population of C. horridus available in some ranges where the species is afforded some state protection. The West Virginia population is mostly available in the eastern fringes of the state - in the east-central and southern counties as well as in the eastern panhandle (Adams, Jennifer P., 2005). The species inhabits the forest and mountainous regions of these counties where forest fragmentation is less and human threats minimal. In the 'Monongahela National Forest' (MNF) the species is designated "Regional Forester Sensitive" (Adams, Jennifer P., 2005). Listings are globally (G) and nationally (N) relevant. C. horridus ranks G4 and N4 in the MNF. According to USFS (2000) this indicates that "The species (or trinomial) is either nationally widespread, abundant, or apparently secure, but with cause for long-term concern" (Adams, Jennifer P., 2005). For the study this implies that the MNF is thus an area that is relatively free of negative human intervention for C. horridus and constitutes a space where control estimates of population sizes can be yielded by the proposed survey. These control estimates can than be compared with estimates of population sizes taken from any other area such as in Mingo or Mercer counties where the snakes may be susceptible to human threats. A significant feature of negative human impact, though passive, is roads that prove to be death-traps for these creatures. Other negative human influences, as stated earlier, are harvesting and killing for economic reasons and negative opinion of snakes that induce people to either kill or destroy habitat (Rudolf and Burgdorf, 1997). For the sake of the study it is assumed that there will be no roads in MNF but there may be in the other area and these should be noted and scanned for dead snakes that shall constitute the count. It is to be noted that Rudolf and Burgdorf (1997) report that of the 36 snakes (C. horridus) they recorded in eastern Texas 16 were found dead on the roads. Another point of interest to note during taking estimates is that snake populations are higher in the same area where there are no roads than in places where there are roads as C. horridus is a species that naturally stays away from human influence (Rudolf and Burgdorf, 1997). Male snakes are more likely to be victims of vehicular traffic than females as their home range is much more extensive (Rudolf and Burgdorf, 1997). Control of Variables: It is not sufficient to only take estimates of population sizes in these two areas without attending to other variables, besides negative human intervention, that also affect snake populations in these areas. It should be noted that variables like temperature and daytime/nighttime should be similar for both areas under survey. Uniformity is, thus, incorporated within the survey techniques. Survey Techniques: The primary survey technique is to enlist staff at Monongahela National Forest and locals at the other site in either Mingo or Mercer County to report snake spottings within the duration of the survey. Both staff and locals will not be required to do more than to be extra watchful as they go about their normal routines in the area. This is to avoid handling C. horridus, which is relatively large and venomous. Also, as is reported, the species is extremely elusive and spotting one requires many man-hours of diligent vigilance. Since the core survey team comprises of only one person it is considered more practical to enlist the help of others in the vicinity of the chosen sites. Thus, also, no specific needs for materials or equipment arise other than sturdy outdoors clothing. The primary techniques are as follows. Specific survey localities and sites within both designated areas should be selected according to information available from DNR records and staff, and from information provided by owners of land adjacent to such localities and sites. Information from the staff at MNF should also be gathered. Areas should be consistent with timber rattlesnake habitat types. Temperature ranges should be optimal (F) (Rudolf and Burgdorf, 1997) for both survey areas during the period of estimate taking. Temperature variations between the two areas should be noted with time period of variation. All sighted C. horridus shall be included within the estimates - adults, female and male, juveniles or young snakes as well as very young neonates. If eggs are spotted these too shall be counted and separately noted. Sex and gravidity, if possible for the spotters, shall be noted within the scope of the study. Dead snakes, especially on roads, shall be counted too. Since the active season in West Virginia varies from April-May to September-October this time period is signified as the one in which the survey will be conducted. It is necessary to make sure that those enlisted for help with spottings should be knowledgeable of C. horridus physiology so that the species is not confused with others in the survey areas and only C. horridus members are reported. If necessary, instructions may be imparted with suitable diagrams and photographs with special attention to sexuality and gravid conditions. Another primary feature of the survey study is to prepare a questionnaire that shall be presented to locals in the two study areas for suitable response. Responses should pay particular attention to respondents' general attitude and beliefs towards snakes, especially a large venomous species like C. horridus. They should also be asked to state whether they actively conserve or destroy the species. Questions should also be designed to elicit suggestions on how people think they and snakes can co-habit without negative confrontation. Questions should also be designed to assess general awareness of aspects of conservation efforts. Implications Crotalus horridus, large and venomous and a potential threat to humans, especially children, are still considered by conservationists and biologists to be a symbolic feature of North American wildernesses. It is in the middle order of the local food-chain and serves as a link between primary and secondary/tertiary feeders. It also serves to keep in check numbers of primary feeders like gophers and rabbits and its demise from the area may cause over-exploitation of vegetation and subsequent damage to the food-web within the local ecosystem (Adams, Jennifer P., 2005). Their utility in controlling crop pests like rodents can also be emphasized to locals to generate some empathy for them. C. horridus is a unique species evolved through millions of years to blend with the local ecosystem as an integral part of it. All these above are true for all family of snakes and this makes it necessary to take steps to conserve them. It is already assumed that the MNF area will be free of human threats while the other area will not. Thus, comparison of population sizes from the two areas will assess the truth value of the hypothesis. If the population size from the MNF area is larger than that of the other area the hypothesis is false and, conversely, true. The survey will also elicit information on ratio of sex and fertility conditions. These are important because they provide indication to the condition of the species in these areas. The most important part of the study, though, is the questionnaire. It will elicit information on how people in the locality treat the snakes. It will enable the study team to determine whether people are actively intervening and whether that is positively or negatively. This will provide important pointers to how conservation efforts inclusive of people's legitimate necessities in relevance to the snakes can be undertaken Since the study is expected to conclusively prove whether negative human intervention has influence on snake populations the attendant questionnaire will also assist in determining how such influence is being projected and how humans can be induced to assist in conservation efforts keeping in mind their own essential requirements in relation with snakes (all members of the suborder inclusive), which themselves are threats to human life. This additional quality of the study will definitely assist in other studies that may be conducted later to investigate influence of humans on snakes aside from providing guiding pointers to future conservation efforts. Reference Adams, Jennifer and Garst, David, Timber Rattlesnakes, Undated. Extracted on 20th October, 2006, from: http://www.wvdnr.gov/Wildlife/Magazine/Archive/03Summer/WDN_Timber_Rattlesnakes.shtm Adams. Jennifer P., 2005, Home Range and Behavior of the Timber Rattlesnake, Presented Thesis. Extracted on 19th October, 2006, from: http://66.218.69.11/search/cachep=Jennifer+P+Adams+Timber+Rattlesnake&prssweb=Search&ei=UTF-8&fr=yfp-t-501&x=wrt&u=www.marshall.edu/etd/masters/adams-jennifer-2006-ma.pdf&w=jennifer+p+adams+timber+rattlesnake&d=eGRK9yQ8NSNI&icp=1&.intl=us Brown, William S., et al, A Case in Herpetological Conservation: Notorious Poacher Convicted of Illegal Trafficking in Timber Rattlesnakes, Chicago Herpetological Society 29, 74-79, 1994. Extracted on 20th October, 2006, from: http://www.skidmore.edu/wbrown/false_cobra/article.html CRACM Staff, 2003, Timber Rattlesnake, Crotalus horridus, Identification, Status, Ecology and Conservation in the Midwest. Extracted on 20th October, 2006, from: http://herpcenter.ipfw.edu/outreach/accounts/reptiles/snakes/Timber_Rattlesnake/TimberRattlerFactSheet.pdf#search='Center%20for%20Reptile%20and%20Amphibian%20Conservation%20and%20Research%202003%20Timber%20Rattlesnake' Rudolf, D. Craig, and Burgdorf, Shirley J., Timber Rattlesnakes and Louisiana Pine Snakes of the West Gulf Coastal Plains: Hypothesis of Decline, Texas J. Sci. 49(3) Supplement 111-122, 1997. Snakes of West Virginia, Timber Rattlesnake, Crotalus horridus, 2003. Extracted on 20th October, 2006, from: http://www.marshall.edu/herp/pages/SNAKES.HTM Bibliography Bender, Paul, 2003, Rattlesnake Research. Extracted on 21st October, 2005, from: http://www.wchstv.com/newsroom/wvwildlife/2003/ww030730.shtml Conner, Richard N., et al, Growth rates and Post-Release Survival of Captive Neonate Timber Rattlesnakes, Crotalus horridus, Herpetological Review, 2003, 34(4), 314-317. Extracted on 20th October, 2006, from: http://www.treesearch.fs.fed.us/pubs/7014 Appendix Figure 1: (Source: Timber Rattlesnake Factsheet, Version: 2003, Center for Reptile and Amphibian Conservation and Management (CRACM), U.S. Fish and Wildlife Service) Figure 2: Distribution of Crotalus horridus in West Virginia (Source: West Virginia Snakes, 2003) Read More