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| HARTMAN BAKKEN,BRADLEY; SABAT,PABLO. |
| Nectar-feeding birds oscillate between avoiding overhydration when they are feeding and preventing dehydration during fasts. Here, we examined how resting rates of total evaporative water loss (TEWL) and metabolic water production (MWP) influence water balance in the green-backed firecrown (Sephanoides sephanoides), a Chilean hummingbird. We hypothesized that a circadian rhythm in TEWL would assuage the dehydration risk that hummingbirds face during the night. However, we did not find support for this idea. In resting hummingbirds, rates of TEWL during the day (54 ±6 µLh-1,n = 8) and night (65 ± 12 h-1, n = 5) were similar. Rates of MWP were also similar between the day (22 ±3 µL h-1, n = 8) and night (23 ± 2 µL h-1, n = 5). MWP rates were significantly... |
| Tipo: Journal article |
Palavras-chave: Circadian rhythm; Evaporative water loss; Hummingbird; Osmoregulation; Water balance. |
| Ano: 2007 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2007000300001 |
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| WOLF,BLAIR. |
| Avian adjustments to desert environments are characterized by an integration of behavior and physiology. These responses serve to maintain homeostasis and conserve vital resources such as water. The small size of birds confers a close coupling to the thermal environment and demands rapid adjustments to environmental challenges. Physiological responses to heat stress include hyperthermia, and increased evaporative cooling as environmental temperatures approach body temperature. Behaviorally, desert birds respond to heat stress by drastically reducing activity during the hottest parts of the day and selecting cool shaded microsites. This characteristic behavioral response presents a potential problem in the face of global warming. If birds totally forgo... |
| Tipo: Journal article |
Palavras-chave: Global warming; Hot deserts; Birds; Water balance; Evaporative water loss; Avian distribution. |
| Ano: 2000 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2000000300003 |
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| SABAT,PABLO; NESPOLO,ROBERTO F; BOZINOVIC,FRANCISCO. |
| Birds living in desert environments have been the preferred models for the study of physiological adaptations to water scarcity. Passerine birds living in marine coastal habitats face similar problems, yet physiological adaptations to water conservation in such species have been poorly documented. We measured total evaporative water loss (TEWL) and rates of oxygen consumption (VO2) in three species of passerine birds dwelling in marine and fresh water habitats. Mass specific total evaporative water loss was significantly lower in the marine species, Cinclodes nigrofumosus, than in species inhabiting areas near freshwater sources. We found a positive relationship between TEWL and VO2. The ratio of TEWL to VO2 (relative evaporative water loss, RTEWL) showed... |
| Tipo: Journal article |
Palavras-chave: Evaporative water loss; Cinclodes; Osmoregulation; Passerines; Salt. |
| Ano: 2004 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2004000200001 |
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