Burrow architecture and burrowing dynamics of Ctenomys in foredunes and paleoenvironmental implications

Abstract

Ctenomys sp., also known as tuco-tuco, is a solitary subterranean small rodent that inhabits sandy soils in South America. We studied burrow system architecture of Ctenomys flamarioni communities from the foredunes of the Southern Brazil Coastal Plain by inserting plaster of Paris and excavating the tunnels. The structure of the burrow system is complex with interlinked tunnels, one occasionally open entrance, multiple chambers and turnarounds, blind laterals, varying slopes, T-junctions, bifurcations, and two different levels. A specific isolated chamber is used as a latrine, while another is used as a nest. The burrow entrance is open only when the rodent is taking out sand or feeding. The tunnels have an average depth of 35cm (deepest at 55cm and the most superficial at 15cm near the entrance). The average burrow length ranges from 190 to 500cm. The tunnels have different heights and widths varying from 5.5–9.3cm wide to 6–11cm high. The entrance is inclined ~28°. The central part of the burrow system has a steeper slope, with an inclination of ~38°. The plaster molds preserve claw marks of four digits of up to 4mm in depth. Collapsed burrows are rapidly sealed to avoid the entrance of predators. Ctenomys sp. burrows provide a suitable microhabitat, which is used by the animals as protection from adverse environmental conditions, particularly during the winter when wind impacts the coastal area. The extensive interlinking tunnels provide underground routes to escape from predators. Ctenomys burrows in coastal dune environments are appreciably more complex than those excavated in arid environments, which are shallower with no chambers and a slope of up to 20°. Such difference in the architecture of the burrows can be used as a criterion to reconstruct the paleoenvironment of burrow systems in the rock record.