Rattlesnakes odor trails

Neonate garter snakes, Thamnophis sirtalis, and brown snakes distinguish conspecific from heterospecific odors (Burghardt 1977, 1983). Newborn timber rattlesnakes, Crotalus horridus, are able to follow conspecific odor trails (Brown and MacLean, 1983). Neonate water snakes are attracted to conspecific odor (Scudder et ah, 1980) and neonate prairie rattlesnakes, Crotalus viridis, to lipoids from the epidermis of adult conspecifics (Graves etal., 1987). 

Odor trails lead from the birthing rookeries of pregnant snakes to their ancestral winter dens. These trails probably help the neonates to find shelter (Graves et al., 1987). Socially naive neonate prairie rattlesnakes were tested for odor... 

First, although the rattlesnakes in our study exhibited SICS, as defined by increased RTF and movement (Chiszar et al., 1977), they did not follow a poststrike odor trail made using only blood. This was not likely a consequence of low blood concentration along the trail. The blood trails presented to snakes were often still very wet when the snake first exited the holding box, whereby the snake body actually smeared the blood trail over which it had moved. 

Second, envenomation does produce a chemical cue that is formed quickly after the strike and immediately secreted fi om the rodent into the environment to produce an odor trail followed poststrike by the rattlesnake (Chiszar et al., 1992b Kardong, 2001). Poststrike, rattlesnakes can follow an odor trail produced by an unstruck mouse (Treatment 2). However, the poststrike trailing success of rattlesnakes significantly improves if provided with the odor trail of a struck mouse (Treatment 1 compared to Treatment 2). Whatever this strike-induced odor cue might be, it is not carried in the blood to surface sites on the rodent for release to the environment. 

Essentially, poststrike trailing rattlesnakes ignored the blood cue, as they exhibited no preference for it over an unstmck mouse odor trail (Treatment 3). Therefore blood odor and mouse odor do not interact in a synergistic way to produce a scent trail of increased perceptibility for the rattlesnake. 

How do neonate prairie rattlesnakes find a hibernaculum of unknown location They may follow adults that have hibernated there before and, hence, know its location (Klauber, 1972). However, rather than using visual and tactual cues to do so, we propose that neonatal rattlesnakes follow odor trails or markings of other snakes - principally adults - to the den. This... 

Brown and MacLean (1983) showed that neonatal timber rattlesnakes (C. horridus) follow odor trails of both adult and neonate conspecifics. Our experiments support the hypothesis that chemical cues from adults may be used in den location by neonatal rattlesnakes, and strengthen this conclusion by extending it to another taxa. These experiments also have determined the locus of production of such chemical cues. Additionally, the findings of Brown and MacLean (1983) that neonate timber rattlesnakes follow trails of neonates as well as adults, and evidence in this paper that neonate prairie rattlesnakes exhibit a locomotory response to neonate skin extracts, suggests that neonates may follow skin-derived odor trails of other neonates, in addition to those of adults, when searching for hibernacula. 

Two phenomena of reptilian prey searching are well investigated responses of various snakes to the odors of invertebrates, and rattlesnakes trailing of envenomated small mammals. 

Overall, rattlesnakes did not follow the blood trail. In some trials with blood, snakes began to trail, exhibiting a predatory interest and SICS, but did not completely follow a blood (or water) trail to its end. TRAIL DISTANCE was used to express this level of trailing. Snakes completed significantly more trailing distance when the odor of a struck... 

Third, blood odor added to the odor of an unstruck mouse does not increase the poststrike trailing success of rattlesnakes (Treatment 3 compared to Treatment 2). 

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