birding-aus

Spinifexbirds

To: <>
Subject: Spinifexbirds
From: "Stephen Ambrose" <>
Date: Sun, 24 Mar 2013 15:47:27 +1100
Dear All,

It's really worth looking at Graeme's website www.graemechapman.com.au to
see more great photos of the Spinifexbird, listen to the audios and to learn
a little bit of this species' ecology.

On his website, Graeme states:

"Throughout the spinifex grasslands the places to look for Spinifexbirds are
along creek lines and in sheltered places where extra moisture allows the
grass hummocks to grow the thickest."

The University of WA and RAOU conducted research on the Spinifexbird on
Barrow Island from 1990-93.  We found that the Spinifexbird needs access to
free water for drinking.  This probably explains why Spinifexbirds are most
often found near creek lines and in other moist microhabitats. The main
source of that water on Barrow Island is dew that condenses on the spinifex
clumps overnight or early morning. Spinifexbirds collected dew in their
breast and belly feathers by rubbing themselves against moist spinifex
grasses. The field water turnover that we measured in these birds indicated
that they must be drinking the droplets of water that were collected by
their feathers, rather than just relying on dietary water intake and
metabolic water production. 

The title and abstract of the scientific paper we published are shown below:

Ambrose, SJ, SD Bradshaw, PC Withers & DP Murphy (1996).  Water and energy
balance of captive and free-ranging Spinifexbirds (Eremiornis carteri) North
(Aves: Sylviidae) on Barrow Island, Western Australia. Australian J. Zoology
44: 107-117
http://www.publish.csiro.au/paper/ZO9960107.htm

Abstract

The mean annual rainfall of Barrow Island, located about 90 km north of
Onslow off the arid Western Australian coast, is 324 mm, 74% of which falls
as cyclonic rain between February and May. Spinifexbirds captured in May
1992 had a mean body mass of 12.3 +/- 0.3 g and a total body water content
(TBW) of 774 +/- 1.6%. In December 1992 the mean body mass was significantly
lower (11.7 +/- 0.2 g; P < 0.05), despite a TBW of 73.4 +/- 1.0%.
Spinifexbirds maintained water balance in both seasons, but water flux rates
were significantly higher in May (P = 0.01). Respective influx and efflux
rates in May were 0.70 +/- 0.30 and 0.72 +/- 0.03 mL (g day)(-1) compared
with 0.60 +/- 0.04 and 0.57 +/- 0.04 mL (g day)(-1) in December. Field
metabolic rates (FMRs), measured with doubly-labelled water ((3)HH(18)0),
did not differ significantly between the two periods. The mean FMR in May
was 6.8 +/- 0.6 mL CO2 (g h)(-1) compared with 7.2 +/- 0.9 mL CO2 (g h)(-1)
in December, similar to rates predicted by Nagy and Peterson (1988) for a
similar-sized passerine. The thermoneutral zone (TNZ) of spinifexbirds,
determined by metabolic laboratory trials in December, extended from 30 to
39 degrees C. The standard metabolic rate (SMR) within the TNZ was 2.9 +/-
0.1 mL O-2 (g h)(-1), which is up to 20% lower than predicted values. Body
temperature was maintained at 39.1 degrees C in the TNZ, but birds became
hyperthermic at ambient temperatures (T(a)s) higher than 35 degrees C, with
body temperatures reaching 44 degrees C. Wet thermal conductance and
evaporative water loss increased markedly at T(a)s > 35 degrees C. The data
suggest that spinifexbirds have limited physiological adaptations to desert
conditions compared with some other arid-zone birds.

Stephen Ambrose
Ryde NSW
 


-----Original Message-----
From: 
 On Behalf Of Graeme Chapman
Sent: Sunday, 24 March 2013 9:27 AM
To: 
Cc: 
Subject: Spinifexbirds

Hello Chris and all,

The Spinifexbird entry on my website is worth a read (and a listen). I wish
I had the time, and the wherewithall to present all the other species so
fully

Cheers

Graeme Chapman
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