Coastal road mortality of land crab during spawning migration

Abstract

Land crabs are threatened by ocean sprawl even though they act as keystone consumers in coastal forest. Female land crabs must migrate to the sea annually to release larvae. However, they face the risk of road mortality which reduces ecological connectivity. We investigated the spawning migration rhythm and the roadkill of land crab. Migrating crabs and roadkilled crabs were recorded on coastal roads in South Korea from July 28 to August 27 in 2018. Female land crabs mainly released zoeae during spring tide. The number of roadkilled crabs also synchronized with migration peak. A majority (95%) of 739 roadkilled carcasses were female crabs. As a result, the female crabs accounted only 29.6% of the population which can lead to a population decline. The roadkill density was the highest in a residential area without cement guardrails. These results suggest the mitigation actions for land crab roadkill. Among them, prohibiting vehicular traffic between sunset and midnight during spring tides in the breeding season should increase the viability of the population.

Road mortality in the blue‐black grassquit (Volatinia jacarina) is seasonally driven and sex‐biased

“…In snakes, extensive movements on their home range and the search for mates may increase the risk of being killed in males (Sosa & Schalk, 2016). In crabs, females are more vulnerable due to the spawning migration (Ryu & Kim, 2021).…”

“…At a smaller scale, territory defence and reproductive behaviour may also influence the probability of animal‐vehicle collisions (Madden & Perkins, 2017; Ryu & Kim, 2021), although such influences are nearly unexplored (Da Rosa & Bager, 2012). For instance, breeding adults in the Pied Flycatcher ( Ficedula hypoleuca ) have higher chances of being killed by traffic during parental care (Kuitunen et al, 2003).…”

Population biology of the endangered land crab Johngarthia lagostoma (H. Milne Edwards, 1837) in the Trindade Island, Brazil: Identifying crucial areas for future conservation strategies

“…The migration of the Christmas Island red crabs ( Gecarcoidea natalis ) is a classic example; the adults move in large numbers from the forests where they live to the beaches where they engage in reproductive behavior, and then the recruits move back to their parent's habitat (Adamczewska & Morris, 2001; Hicks, 1985). This expressive migration makes it possible to delimit the travel route more intuitively and define the crabs' breeding and residential areas on the island, an information that has been used in management strategies such as the closure of roads in areas used by crabs to avoid them being hit by cars (Ryu & Kim, 2021). However, delimiting the travel route becomes a major challenge for other terrestrial crab species that migrate less intensively (as Johngarthia malpilensis —according to López‐Victoria & Werding, 2008) and inhabit locations of difficult access (as Gecarcinus ruricola— according to Hartnoll et al., 2006a, 2007; and Hartnoll & Clark, 2006).…”

A biologically realistic model to predict wildlife-vehicle collision risks

“…For example, not only do animals cross roads, but they can roam along roadsides to forage hence putting them at much higher risk of being hit by a car (scavenging: Schwartz et al 2018;Ratton et al 2014, hunting: Gomes et al 2009D'Amico et al 2013, salt licking: Fraser & Thomas 1982. More importantly, collision probabilities in a landscape are intrinsically linked to the number of encounters an animal has with roads, and peaks in activity such as mate searching, breeding and juvenile dispersal have repeatedly been cited to explain seasonal patterns in WVC numbers (Steiner et al, 2014;Ryu & Kim, 2021;Raymond et al, 2021). Despite this, the influence of patterns of space use by animals on WVC has yet to be adequately addressed in mechanistic models.…”