Significance Using measured rates of evaporative water loss, hourly gridded weather data, a 4 °C warming scenario, and physiological models, we show that songbirds in the deserts southwestern United States are increasingly susceptible to death from dehydration on hot days. Smaller birds lose at proportionally higher rate, hence more vulnerable than larger lethal arising greater cooling demands. Our analysis indicates that, by end present century, exposure potentially conditions could least...

Birds show phylogenetic variation in the relative importance of respiratory versus cutaneous evaporation, but consequences for heat tolerance and evaporative cooling capacity remain unclear. We measured water loss (EWL), resting metabolic rate (RMR) body temperature (Tb) four arid-zone columbids from southern African [Namaqua dove (Oena capensis, ∼37 g), laughing (Spilopelia senegalensis, ∼89 g) Cape turtle (Streptopelia capicola, ∼148 g)] Australia [crested pigeon (Ocyphaps lophotes), ∼186...

Abstract Facultative hyperthermia, the elevation of body temperature above normothermic levels, during heat exposure, importantly affects water economy and balance terrestrial endotherms. We currently lack a mechanistic understanding benefits hyperthermia provides for avian taxa. has been proposed to minimize rates loss via three distinct mechanisms: M1) by maintaining ( T b ) environmental temperatures e ), can be lost non‐evaporatively, saving water; M2) minimizing thermal gradient when...

Evaporative heat loss pathways vary among avian orders, but the extent to which evaporative cooling capacity and tolerance varies within orders remains unclear. We quantified upper limits thermoregulation under extremely hot conditions in five Australian passerines: yellow-plumed honeyeater (Lichenostomus ornatus; ∼17 g), spiny-cheeked (Acanthagenys rufogularis; ∼42 chestnut-crowned babbler (Pomatostomus ruficeps; ∼52 grey butcherbird (Cracticus torquatus; ∼86 g) apostlebird (Struthidea...

Little is known about the phylogenetic variation of avian evaporative cooling efficiency and heat tolerance in hot environments. We quantified thermoregulatory responses to high air temperature (Ta) ∼100-g representatives three orders, namely, African cuckoo (Cuculus gularis, Cuculiformes), lilac-breasted roller (Coracias caudatus, Coraciiformes) Burchell's starling (Lamprotornis australis, Passeriformes). All species initiated respiratory mechanisms increase dissipation when body (Tb)...

Sandgrouse (Pterocliformes) are quintessential examples of avian adaptation to desert environments, but relatively little is known about the limits their heat tolerance and evaporative cooling capacity. We predicted that in Burchell's sandgrouse (Pterocles burchelli) highly efficient provides basis for very high air temperature (Ta). measured body (Tb), resting metabolic rate (RMR) water loss (EWL) at Ta between 25°C ∼58°C birds exposed successive increments Normothermic Tb averaged 39.0°C,...

Birds in the order Caprimulgiformes (nightjars and allies) have a remarkable capacity for thermoregulation over wide range of environmental temperatures, exhibiting pronounced heterothermy cool conditions extreme heat tolerance at high temperatures. We measured thermoregulatory responses to acute stress three species caprimulgiforms that nest areas aridity, common poorwill (Phalaenoptilus nuttallii: Caprimulgidae) lesser nighthawk (Chordeiles acutipennis: Sonoran Desert Arizona, Australian...

Avian orders differ in their thermoregulatory capabilities and tolerance of high environmental temperatures. Evaporative heat loss, the primary avenue whereby it occurs, differs amongst taxa. Although Australian parrots (Psittaciformes) have been impacted by mass mortality events associated with extreme weather (heat waves), physiology has not well-characterized. We quantified upper limits to thermoregulation under extremely hot conditions two parrots: mulga parrot (Psephotellus varius; ∼55...

The thermoregulatory responses of owls to heat stress have been the subject few studies. Although nocturnality buffers desert-dwelling from significant during activity, roost sites in tree and cactus cavities or deep shade provide only limited refuge high environmental temperatures day. We measured acute two species small owls, elf owl (Micrathene whitneyi) western screech-owl (Megascops kennicottii), which occupy Sonoran Desert southwestern North America, an area extreme aridity. exposed...

Birds inhabiting hot, arid ecosystems contend with trade-offs between heat dissipation and water conservation. As temperatures increase, passerines engage in various behaviors to reduce exposure heat, solar radiation insolation, reradiation of from the ground. These responses rising may result subordination reproductive urgency or nutrient acquisition need for thermoregulation. During studies on Arizona Grasshopper Sparrow (Ammodramus savannarum ammolegus) life history ecology, we noted that...

Abstract Gunnison's prairie dog ( Cynomys gunnisoni ) is an herbivore that ranges from desert grasslands to high‐montane meadows and limited by disease across much of its range. The importance abiotic drivers the population dynamics species poorly known. We employed stable isotope analysis investigate energy assimilation patterns as indicators limitation in arid grassland montane populations C. during a multi‐year drought. Standard ellipse areas plasma red blood cell carbon (δ 13 C) nitrogen...

Evaporative cooling is a prerequisite for avian occupancy of hot, arid environments, and the only avenue heat dissipation when air temperatures (Ta) exceed body temperature (Tb). Whereas diurnal birds can potentially rehydrate throughout day, nocturnal species typically forgo drinking between sunrise sunset. We hypothesized that have evolved reduced rates evaporative water loss (EWL) more economical mechanisms compared to species, permitting tolerate extended periods intense without becoming...

Abstract Little is known about the phylogenetic variation of avian evaporative cooling efficiency and heat tolerance in hot environments. We quantified thermoregulatory responses to high air temperature ( T a ) ~100-g representatives three orders: African cuckoo Cuculus gularis , Cuculiformes), lilac-breasted roller Coracias caudatus Coraciiformes), Burchell’s starling Lamprotornis australis Passeriformes). All species initiated respiratory mechanisms increase dissipation when body b...

Abstract Evaporative cooling is a prerequisite for avian occupancy of hot, arid environments, and the only avenue heat dissipation when air temperatures (T ) exceed body temperature b ). Whereas diurnal birds can potentially rehydrate throughout day, nocturnal species typically forgo drinking between sunrise sunset. We hypothesized that have evolved reduced rates evaporative water loss (EWL) more economical mechanisms than those permit them to tolerate extended periods intense without...