Gas composition and its daily changes within burrows and nests of an Afroalpine fossorial rodent, the giant root-rat Tachyoryctes macrocephalus

Fossorial mammals are supposed to face hypoxic and hypercapnic conditions, but such conditions have been rarely encountered in their natural burrow systems. Gas composition in burrows after heavy rains, deeper burrows and especially nest chambers, where animals usually spend most of the day, could be even more challenging than in shallow burrows. Such situations, however, have been rarely surveyed in the wild. In our study, we determined concentrations of O2, CO2 and CH4 in active burrows and nests of the giant root-rat Tachyoryctes macrocephalus, a large fossorial rodent endemic to the Afroalpine zone of the Bale Mountains in Ethiopia. We were able to determine the precise location of nests by tracking individuals equipped with radio-collars. To the best of our knowledge, this is the first study that analyses air samples taken directly from the nests of actually occupied burrow systems in any free-living fossorial mammal. We found no evidence for environmental hypoxia in the examined burrows and nests (range 19.7–21.6% O2). Concentrations of CO2 in the burrows increased after the burrows were plugged in the evening, but did not reach physiologically problematic levels. The highest CO2 concentrations in burrows were detected in the evening during a wet period (up to 0.44%). In root-rat nest chambers, the highest (but still harmless) CO2 concentrations (up to 1.31%) were detected in the morning (measured in the late dry season only) together with an elevated concentration (up to 13.5 ppm) of CH4. Regular surface activity of giant root-rats, combined with the relatively large dimensions of their nest chambers and tunnels, and the absence of heavy soils, may contribute to harmless atmospheres within their burrow systems

Urbanization and raptors : trends and research approaches

Urbanization presents a major global issue for the conservation and survival of many different species. With the increasing footprint of cities and intensification of our use of urban areas, wildlife faces extremely difficult challenges to live there. Understanding how species respond to urban processes and how to design urban landscapes that facilitate species’ presences are major emerging research and management priorities. Despite general negative responses to increasing urbanization, some animal taxa, both native and introduced, appear to benefit from urban environments by capitalizing on novel environments and abundant resources.1 Those that are common in urban systems display particular physical characteristics and ecological traits.2,3,4 They also frequently display a level of behavioral plasticity or tolerance, adjusting their behavior to interact with, and survive in, urban environments.5,6 Termed urban-adaptors,7 these species may exhibit altered spatial,8,9,10 foraging,11,12 and breeding behaviors,13 as detailed in chapter 2