A simple, band-mounted device to measure behaviorally modified thermal microclimates experienced by birds

Abstract

Birds encounter climate at the scale of microclimates that can vary rapidly in time and space and so understanding potential vulnerability and adaptations to those microclimates requires fine-scale measurements that accurately track thermal exposures. However, few options exist for recording the microclimates actually experienced by birds (realized microclimates). We constructed and tested a simple, lowcost, temperature logger for recording the realized microclimates of ground-nesting birds. We developed attachment protocols for band-mounting Thermochron iButtons on Ring-billed Gull (Larus delawarensis) chicks. We tested these mounted, temperature-logging devices on 20 chicks weighing > 200 g (device weight was 4 g), attaching devices for 48 h and observing behavior before and after attachment and removal. Devices recorded temperature immediately surrounding the leg at 2-min intervals. Recorded temperatures were strong predictors of observed thermoregulatory behaviors (panting and sitting), outperforming predictions based on air temperatures measured by basic, static approaches. Through comparison with matched controls (chicks with just a band), we detected no adverse physiological effects of devices, no effects on social or feeding behavior, and only a short-term decrease in inactivity immediately after device attachment (likely due to increased preening). By attaching iButtons to the legs of birds, we quantified realized thermal exposure, integrating air temperature, modes of environmental heat transfer, and bird behavior at microclimatic scales.Although not yet validated for broader use, our approach (including possible miniaturization) should be suitable to measure thermal exposure of adults, not just chicks, allowing collection of data concerning thermal exposures during flight under field conditions. At~$25 USD per device, our approach facilitates experimental protocols with robust sample sizes, even for relatively modest budgets.

Avian adjustments to cold and non‐shivering thermogenesis: whats, wheres and hows

“…(a) Huddling and crowding Some birds crowd and/or flock together to share body heat and minimize heat loss, for example tree swallows (Tachycineta bicolor), crows (Corvus spp. ), ravens (Corvus corax) and ring-billed gulls (Larus delawarensis) (French, 1998;Heinrich, 2014;Arnold & Oswald, 2018;Whittow, 1986). Many birds like nuthatches (Sitta spp.…”