Spool-and-line studies on the behavioural ecology of rats (Rattus spp.) in the Galápagos Islands

Abstract

The spool-and-line technique has been neglected in the study of the behavioural ecology of mammals. It has advantages over the more widely used method of radio tracking in terms of cost and depth of detail in the data obtained, despite its limitations. A spool and line was used to study habitat use of two species of Rattus on Santa Cruz Island, Galápagos, in areas of sympatry and allopatry. Significantly longer total spool lines were collected from R. rattus than R. norvegicus, and R. rattus also climbed trees significantly more. Significantly longer spool lines were collected from female than male R. rattus, and rats caught in the morning spent significantly more time on the ground than those caught at night. The method of handling and the occasion of capture (first, second, or third) had no significant effect on either the total length of spool line collected or the proportion of time spent on the ground. Arboreality in R. rattus was compared with that in R. norvegicus between areas of sympatry and allopatry, and a significant difference was found between sites in terms of both the total length of spool line collected and the proportion of time spent on the ground. Rattus rattus was least arboreal at site D, an area of allopatry, and most arboreal at site B, where the fewest trees occurred, suggesting that factors other than vegetation structure influence arboreality. The use of spool-and-line devices in the study of behavioural ecology is discussed.

Biology and Impacts of Pacific Island Invasive Species. 11.Rattus rattus,the Black Rat (Rodentia: Muridae)

“…The directions of rat movements are often unpredictable because their exploratory behavior is influenced by both scents and other features that are encountered in the environment ( Barnett 1963). Often a R. rattus individual doubles back over its same pathway by circling or moving a few decimeters in one direction, then returns to a point that it had already traveled before it quickly changes paths and explores a new direction ( Key andWoods 1996, Shiels 2010). The average height R. rattus was observed active aboveground was 2.8 m (Shiels 2010), yet black rats can spend an average of 30% -90% of their night activity on the ground (Dowding and Murphy 1994, Hooker and Innes 1995, Lindsey et al 1999, Shiels 2010.…”

Tree-climbing capabilities of Norway and ship rats

“…For example, Key & Woods (1996) tracked individuals of both species, in sites of sympatry and allopatry, in the Galapagos Islands. They used the spool-and-line method to determine the amount of time each species spent in the forest canopy.…”

Use of space by the Neotropical caviomorph rodent Thrichomys apereoides (Rodentia: Echimyidae)

“…Each marked individual received a tracking spool (4 g, line length of 400 m) (BOONSTRA & CRAINE 1986), which was wrapped in plastic wrap and tape, then glued to the back of the animal with cyanoacrylate glue (Superbonder ® ) (RYAN et al 1993, KEY & WOODS 1996, CUNHA & VIEIRA 2002. The line of the spool was tied to an object at the point of release of each animal.…”