2.1 Study area
We deployed paired temperature loggers (one within and one outside each
pond) in 16 intermittent ponds in the Coronado National Forest, located
within the Huachuca Mountains Canelo Hills (HMCH) region and San Rafael
Valley of southeastern Arizona, USA in June and July 2018 (Figure 1).
The HMCH region is part of the Madrean Sky Islands, with an elevation
range of approximately 1150 m to 2880 m. Habitat composition includes
cienega wetlands, semi-arid grasslands and thorn-scrub, and evergreen
and coniferous woodlands. The climate of this region is semi-arid, with
up to half of the annual rainfall occurring during the summer monsoon
season (Sheppard et al., 2002). Rain events during the monsoon season
are typically short in duration, high in intensity, and seasonally
predictable but spatially variable (Goodrich et al., 2008). Ponds in the
region were originally constructed to provide water for livestock and
are often called “stock tanks”; these ponds are now surrogating for
aquatic habitat lost to human activities and support a range of aquatic
species (Rosen & Schwalbe 1998; Storfer et al. 2014; Mims et al. 2016).
We selected ponds based on historical hydroperiod data that indicated
they were generally intermittent and tended to have longer
(>1 month) duration wetted phases (Parsley et al., 2020).