Development of Thermoregulation in Three Species of Tropical Seabirds
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Date
1988-12Author
Mathiu, Mbaabu P
Type
ThesisLanguage
enMetadata
Show full item recordAbstract
'The development of thermoregulation was studied in three species
of tropical seabirds: Sooty Tern (Sterna fuscata), Brown Noddy
(Anous stolidus) and the Wedge-tailed Shearwater (Puffinus
pacificus) . late prehatichinq stages (unpipped, externally pipped,
internally pipped and pip-holed eggs) of eggs, and hatchlings were
subjected to small decrements in ambient temperature (Ta) and their
oxygen consumption (V02) and body temperature ('Ib) measured.
Evaporative water loss and respiratory frequencies of hatchlings at
higher temperatures were also measured together with musc.Iemass,
downmass, and length (thickness).
All the egg developmental stages showed a direct coupling of . their V02 and 'Ib to ambient temperatures. On the other hand the hatchlings showed a homeothermic of metabolic response to Ta.
The increase in V02 below the thermoneutral zone peaked and then fell
precipitously with further reduction of Ta. Hatchling rectal
temperatures (Tre) increased slowly with Ta between the temperature at
which this metal:x>lic decline began and the upper limit of
thermoneutrality. 1\rx:Jve the thermoneutral zone, Tre increased at a
faster rate but the Sooty Tern and Brown Noddy hatchlings maintained
their Tre below Ta above 4°0C. Evaporative water loss and respiratory
rates increased dramatically above the thermoneutral zone.
v
No homeothermic response was observed. during the late
prehatching, but hatchlings showed a homeothermic response
qualitatively similar to that of the adults. 'Ihe hatching process
seems to be crucial for this transition and the probable underlying
chances are d; scussed, Hatchling Sooty Terns p:>SSeSS the best
overall thermoregulatory abilities arrong the three species. Hatchling
BraNn Ncx:kiiesthenroregulate better during heat stress than cold
stress, whereas the Shear water hatchlings do the reverse. Using their
therm:::xJenic capacities and the difference between their Lower'critical
.
temperature am the Ta at which peak V02 occurred, the hatchlings are
ranked from least to most semi precocial in the following order: Brown
noddy, sooty Tern am Wedge-tailed Shearwater.
Publisher
University of Nairobi
Rights
Attribution-NonCommercial-NoDerivs 3.0 United StatesUsage Rights
http://creativecommons.org/licenses/by-nc-nd/3.0/us/Collections
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