Mate location tactics in garter snakes: effects of rival males, interrupted trails and non‐pheromonal cues

Abstract

Summary 1.The ability to follow substrate-deposited scent trails using sophisticated vomeronasal abilities is a key feature of snake biology. However, previous research on this topic has derived mostly from a highly artificial test situation: captive snakes following continuous trails over structurally simple homogeneous substrates, in the absence of any other cues (e.g. visual or olfactory) either from the target of that search or from other snakes. 2. Our field experimental trials with Red-Sided Garter Snakes ( Thamnophis sirtalis parietalis ) at a communal den in Manitoba explored wider issues in mate location. 3. Males followed a female's trail less successfully if she had recently been followed by rival males, suggesting that trailing males obscured the cues left by the female. 4. Males that lost contact with a female's trail exhibited stereotyped, spatially extensive and prolonged circling behaviour centred on the last point at which the trail was detectable; in nature, this behaviour would maximize the male's ability to relocate a discontinuous trail. 5. Trail-following males switched from chemical to visual cues as soon as they were close to a female, enhancing speed but decreasing the accuracy of mate location (because males could distinguish between females and other males based on either visual or airborne olfactory cues). 6. Incorporating additional cues and broader spatial scales can clarify aspects of trail-following behaviour not evident from studies in small, highly simplified laboratory situations.

Anthropogenic noise disrupts mate searching in Gryllus bimaculatus

“…Many animal communication systems are heavily influenced by sexual selection due to their importance to reproductive success (Andersson 1994). Of these systems, some fall into the broad category of 'mate location signals' which are signals that have evolved, at least in part, to convey information about the location of the signaller so that a conspecific receiver can locate them and mating can occur (Tyack 1981;Rutowski et al 2001;Shine et al 2005;Allen et al 2012). Species that utilize these signals include those that are solitary or dispersed over large home ranges (e.g.…”

“…male Empress Leilia butterflies, Asterocampa leilia, detect females using visual signals; Rutowski et al 2001), but these signals are also observed in species which live socially, or in close proximity to conspecifics (e.g. female garter snakes, Thamnophis spp., signal to attract males using pheromones; Shine et al 2005). Thus, mate location occurs through different social structures, but also through different modalities.…”

The scent of the others: chemical recognition in two distinct populations of the European whip snake, Hierophis viridiflavus

“…Conspecific trailing behaviour (the ability to follow substrate-borne cues left in the environment by conspecifics) in snakes is mediated by semiochemicals located in the skin (Garstka and Crews, 1981;Greene and Mason, 1998) and laid down passively on the substrate (LeMaster and Shine et al, 2005). Both in the garter snake, Thamnophis sirtalis parietalis and in the brown tree snake, Boiga irreg-ularis species-specific skin lipids acting as female sexual attractiveness pheromones are responsible for eliciting male trailing behaviour (Greene, Stark and Mason, 2001;.…”

Responses of an araneophagic assassin bug, Stenolemus bituberus, to spider draglines

“…Traces may also attract potential mates. For example, male white-spotted longicorn beetles Anoplophora malasiaca are attracted to chemical cues from females ( Fukaya et al , 2004 ), and male garter snakes ( Thamnophis sirtalis parietalis ) use cues left behind in the trails of females to locate potential mates ( Shine et al , 2005 ).…”