Cotton spools as an animal tracking tool

We have attached cotton spools to the tails of dragon lizards and goannas to get an accurate understanding of their daily movement patterns.

Cotton spools are light weight (~4g) and contain about 250-280m of cotton/nylon thread (Plate 1). The cotton pulls away from the centre of the spool, so the spool can be attached to the animal.

Plate 1. Cotton spool

Cotton spools are low technology but have two advantages over GPS units that can also be attached to animals to record movement data. Firstly, as the researcher must retrieve the cotton and record where it has been laid, the person has a real on-the-ground appreciation of the habitat that has been utilised by the animal. Such information is often not available at a fine scale when using GPS units on animals. Secondly, if you are monitoring the movements of an arboreal animal, then this is recorded, as the cotton trail follows the exact path of the animal through a shrub or a tree. GPS units are generally unable to record vertical movements in bushes and trees.

We used cotton spools for two particular projects. The first was to determine daily movement patterns of Gould’s goanna (Varanus gouldii) in Karrakatta Cemetery. In this project (Thompson 1992), two cotton spools were attached to the base of eight Gould’s goannas and their movement recorded for between four and 18 days. As an indication of the type of data that can be recorded, Plate 2 is the path travelled by two goannas in a 24 hour period. This methodology also provides an accurate record of the total distance moved. In Karrakatta Cemetery, Gould’s goannas foraged in the leaf litter for invertebrates which were their primary source food (Thompson 1996). We were able to determine from the cotton spool those areas in which each goanna foraged, as the cotton thread would indicate where the animals moved back and forward through a particular area on multiple occasions searching for prey items. When movement and dietary data were combined a more complete picture of the ecology of the species in a local context is provided.

In a second study we attached cotton spools to the tails of the Western Bearded Dragons (Pogona minor) to record their movement patterns on a rehabilitated minesite waste dump (Thompson and Thompson 2003). The cotton spools technique proved to be particularly informative as we were able to obtain an appreciation of the movement of these Bearded Dragons in bushes. The average daily distance travelled by 19 Bearded Dragons was 115m, which corresponded to a linear distance of 68m. They are earlier colonisers of rehabilitation areas because they move appreciably greater distances than other dragon lizards, are spatially widely-foraging, frequently forage in saltbush (Atriplex spp.; Plate 3) and bluebush (Maireana spp.) and regularly traverse open areas or up and down steep slopes which are plentiful on rehabilitated waste dumps in the Goldfields.

Plate 2. Movement patterns of two Gould’s goannas in Karrakatta Cemetary (taken from Thompson 1992, p 749, Figure 2)

Plate 3. Western Bearded Dragon with a cotton spool attached in an Atriplex sp. bush

Cotton spools have been used on a range of other species including frogs (Seabrook and Dettmann 1996), Bobtail Lizards (How and Bull 2006), rat-kangaroos (Dennis 2002) and bettongs (Vernes and Haydon 2002) to record movement patterns.

References

Dennis, A. J. 2002. The diet of the musky rat-kangaroo, Hypsiprymnodon moschatus, a rainforest specialist. Wildlife Research 29:209-219.

How, T. L. and C. M. Bull. 2006. Reunion vigour: an experimental test of the mate guarding hypothesis in the monogamous sleepy lizard (Tiliqua rugosa). Journal of Zoology 257:33-338.

Seabrook, W. A. and E. B. Dettmann. 1996. Roads as activity corridors for Cane Toads in Australia. Journal of Wildlife Management 60:363-366.

Thompson, G. 1992. Daily distance travelled and foraging areas of Varanus gouldii (Reptilia: Varanidae) in an urban environment. Wildlife Research 19:743-753.

Thompson, G. G. 1996. Notes on the diet of Varanus gouldii in a semi-urban environment. Western Australian Naturalist 21:49-54.

Thompson, S. A. and G. G. Thompson. 2003. The western bearded dragon, Pogona minor, (Squamata: Agamidae): An early lizard coloniser of rehabilitated areas. Journal of the Royal Society of Western Australia 86:1-6.

Vernes, K. and D. T. Haydon. 2002. Effects of fire on northern bettong (Bettongia tropica) foraging behaviour. Austral Ecology 26:649-659.