Supplementary Methods
Study area. The forest of Kirindy/CFPF is a dry deciduous forest near the west coast of
Madagascar. This area is characterised by a marked dry season during the austral winter
with virtually no precipitation from April through October. The coldest months are June
and July, with very high diurnal fluctuations in temperature (between about 10 and
35 °C). During the dry winter months, there is no open water available. Fruits are
produced throughout the year, but have a higher fibre and lower sugar and water content
during the dry season. Most rain falls during the hottest months between December and
February with an annual mean of 800 mm. A more detailed description of the area is
given by1.
Experimental procedure. All experiments were done in the field under natural
conditions using wild animals, and comply with the current laws of the country where
they were performed (approving committee: „Commission Tripartite“ of the Malagasy
government).
Trapping. Animals were caught once a month in four consecutive trap nights during
their activity period (Dec 1998 – April 1999, Dec 1999 – April 2000, Dec 2001 – April
2001, Feb 2003 – March 2003). Animals were sexed, measured, weighed and
individually marked. For details see2. Selected animals were equipped with radio
transmitters (see below).
Temperature measurements. Body temperature (Tb) of the animals was measured
using pre-calibrated, frequency mediated, temperature-sensitive collar transmitters (4 g
TW-4 button cell tags, Biotrack Ltd., Wareham, Dorset, UK). The pulse rate was timed
with a stopwatch. Signals were detected using a TR-4 receiver (Telonics, Inc., Mesa,
Arizona, USA) with a flexible two-element yagi antenna.
Tb was recorded in hourly intervals for periods of up to 26 continuous days.
During the entire study (1999-2003) Tb records from 53 different adult individuals (33
males and 20 females) were obtained for a total of 105 days during the rainy season
(activity period; February – March), 94 days during the transition period (April), and
1836 days during the dry season (period of hibernation; May – August).
For calibration of this method, four animals were equipped with both,
intraperitoneally implanted (4 g, Ökokart, Munich, Germany) and collar transmitters.
The accordance between the measurements of the two kinds of transmitters proved to be
extremely high, especially during the phases of inactivity, when the animals curl up
with the collar transmitter positioned firmly inside (in prep. by K.H.D.). Thus, the data
gained by the collar transmitters closely reflect the core Tb and were sufficiently
accurate for this study, especially during hibernation.
Furthermore, six animals (three males and three females) were subcutaneously
implanted with temperature loggers (3 g, thermochron i-buttons, Dallas Semiconductor,
USA) during one study period (2001). However, only four animals (one male and three
females) could be recaptured after the hibernation period, yielding 343 days of body
temperature records during the hibernation period.
For some animals, data were collected over several seasons, resulting in a total of
66 animal seasons (Tab. S1). For the analyses, means of each animal per season were
calculated. Whenever data from more than one season were available for an individual,
only the season with the most data points was used. Therefore, every animal was
included only once in the analyses, and N refers to the number of different animals
considered in the analyses, whereas n gives the total number of analyzed data points
pooled together for all analyzed animals.
1
Wherever possible, relevant ambient temperature (Ta) and tree hole temperature
(Th) were measured together with Tb, using temperature loggers (TinyTalks, Orion
Components, Chichester, UK; thermochron i-buttons). Th was taken with loggers placed
inside the tree holes about 10 cm away from the animals. Ta was obtained with data
loggers which were installed on the southern (shady) side of the tree at the height of the
tree hole and covered from direct sun with a white roof. Measurements were recorded
continuously every 20 or 30 minutes.
Radio-tracking. Sites of the sleeping holes of the radio-collared animals were
determined daily with the help of the transmitters and telemetry equipment. Whenever
the sleeping hole was at a height of less than 4.5 m, identities of the animals were
additionally checked with the transponder reading system.
2
Table S1 Number of study animals
total
one season
two seasons three
animal
seasons
seasons
females
20
16
3
1
25
males
33
25
8
-
41
N=
53
41
11
1
66
Overview over the number of animals used for body temperature measurements over the
entire study period (1998-2003). Total gives the total number of different individuals
measured, animal seasons shows the number of available data sets, including multiple
seasons per animal.
3
Reference List
1.
Ganzhorn, J. U. & Sorg , J.-P. Ecology and Economy of a Tropical Dry Forest in
Madagascar. (Erich Goltze GmbH & Co KG, Göttingen, 1996).
2.
Fietz, J. & Ganzhorn, J. U. Feeding ecology of the hibernating primate
Cheirogaleus medius: how does it get so fat? Oecologia 121, 157-164 (1999).
4