EFFECTS OF SUBSTRATE ON THE DISTRIBUTION OF MAGELLANIC PENGUIN (SPHENISCUS-MAGELLANICUS) BURROWS

Slope and texture of substrate influenced distribution of penguin burrows at a large colony of Magellanic Penguins (Spheniscus magellanicus) at Punta Tombo, Argentina. Burrows were most numerous in substrate that consisted mostly of fine particles (silt and clay), with small amounts of sand or gravel. Few burrows were found in substrate with large proportions of sand or gravel. Burrows were more common on slopes than on level ground. More chicks were fledged from burrows in substrates with high amounts of silt and clay and low amounts of sand than from burrows in other substrates. These patterns reflect differences in burrow stability, susceptibility to flooding, and excavation effort. Slope, depth, and texture of substrate should be considered in decisions about protection of penguin breeding habitat.