home ranges

Written by Noel Ellis, Green Talent Placement

The area in which an animal stays for most of their daily activity is known as their home range. Often (though not always), this is the same as their territory, the area which they mark out and defend from unwanted intruders (O’Donnell and delBarco-Trillo, 2020; Crane et al., 2021). Reptiles cannot fly between different habitats like birds, and unlike mammals primarily travel while the sun is up. Still, reptiles can maintain home ranges and move impressive distances (Crane et al., 2021).

The size of reptile home ranges can vary drastically depending on the population density, habitat characteristics, availability of food and many other factors (Day, 2012; O’Donnell and delBarco-Trillo, 2020). Additionally, British reptiles all overwinter or brumate during the colder months, staying in one area to conserve energy. In the spring and summer, some species move large distances to breeding, feeding or nesting areas depending on their life stage and current condition (Reading and Jofré, 2009).

The three native lizard species in Britain have home ranges that have been studied and recorded in certain environments.

Common Lizard – typically between 0.05 and 0.1 hectares, with males sometimes up to 0.15 ha (Day, 2012). Males are also territorial in their early spring breeding season, defending their home ranges from other males.

Slow Worm – normally around 0.02 hectares, but can be as low as 50m² (0.005 ha) (Smith, 1990). Many individuals often overlap in a single range, even in the late spring breeding season where males compete for mates, there do not seem to be clear territories (Smith, 1990; Hubble and Hurst, 2006).

Sand Lizard –  between 0.05 and 0.2 hectares, with males having large ranges more often. Sand lizard home ranges in Britain also overlap between individuals, as larger areas cannot be effectively defended by a single lizard (Nicholson and Spellerberg, 1989).

In comparison, the three native snake species in Britain have fairly large home ranges, and have proven to be more difficult to effectively pin down scientifically.

Grass Snake – their range depends heavily on the habitat, but often falls between 20 and 40 hectares (Cathrine, 2016). Males move more often in the spring mating season, and females more often in the early summer to lay eggs, however both sexes can travel hundreds of metres daily, and often change home ranges each year (Reading and Jofré, 2009).

Adder – not well studied in the U.K., but generally small at between 0.05 and 0.5 hectares (Nash and Griffiths, 2018). They are able to move several metres per day, particularly when placed in a new environment, and when moving to and from their overwinter sites (Andersson, 2003; Nash and Griffiths, 2018).

Smooth Snake – around 0.3-0.5 hectares for juveniles, 1 hectare for adult females and 1.85 hectares for adult males. Males move around more often and greater distances than females in the breeding season of early spring, and in the late summer as they return to their overwinter spots (Reading, 2012).

And of course Leatherback Sea Turtles travel thousands of miles in the open ocean, moving between tropical nesting areas, and temperate or even polar regions to feed (Houghton et al., 2006).

Even as we continue to learn about the movement of our reptile species, key to effective conservation is giving animals the space and suitable habitat to move and change location and range if they need to. Juvenile animals, including reptiles often make risky journeys to find and establish their own home range, and can die in large numbers if routes are not available (Andrews, Langen and Struijk, 2015).

Creating wildlife corridors and plus removing harsh movement barriers can ensure that lizards and snakes can find the resources and conditions they need to survive, no matter how big or small that area ends up being (Turner et al., 2023).

Click here for references