Variability in the Daily Activity of the Nine-banded Armadillo across the Americas

Abstract

            The nine-banded armadillo (Dasypus novemcinctus) is a mammal species of great ecological importance to the Americas.  Originally native to South America, it has expanded its range as far north as the Midwestern United States and currently has one of the largest ranges of any armadillo species.  Their large geographic distribution has led to a large diversity of conditions in which they reside, with variations in seasonality, temperature, and landcover types.  The nine-banded armadillo is traditionally regarded as nocturnal in the tropics from which it originates, but its daily activity patterns have been shown to be plastic.  Using camera trap data from across the Western Hemisphere, these variables were shown to affect the timing of the daily activity of this species.  Temperature had the most significant effect; higher temperatures lead to a shift in activity, causing later activity in the morning and a delay in the uptick in activity in the evening.  Seasonal differences in activity are observed in extratropical regions, but this appears to be almost entirely due to temperature differences between seasons.  Finally, landcover does not play a significant role in the variability of activity patterns, except for artificial surfaces creating a similar shift that higher temperatures do, possibly due to their higher thermal absorption leading to hotter microclimates.  The nine-banded armadillos’ flexibility in responding to different abiotic constraints is an important factor in determining the northernmost extent of its range spread and its fitness in new conditions.