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Electronic Appendix
To
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Microclimate and microhabitat selection of the Alpine
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Rock Ptarmigan (Lagopus muta helvetica) during
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summer
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Linda Visinoni a, Claire Agnès Pernollet
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Lukas Jenni a
a,c
, Jean-François Desmet b, Fränzi Korner-Nievergelt a,
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a
Swiss Ornithological Institute, Seerose 1, 6204 Sempach, Switzerland
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b
Groupe de Recherches et d'Information sur la Faune dans les Ecosystème de Montagne, 74340
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Samoëns, France
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c
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Migratrice, La Tour du Valat, Le Sambuc, 13200 Arles, France
present address: Office National de la Chasse et de la Faune Sauvage, CNERA Avifaune
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Appendix S1: Daily course of ground temperature at four different microtopographic sites
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Below a rock, mean ground temperature did not vary much between day and night; it was slightly
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higher at night and much lower during the day than at the other three sites (Fig. S1a). Also the
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variance between days was smaller than at the other three sites (Fig. S1b). The highest mean
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ground temperatures during the day and the lowest during night were reached on rocks with
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vegetation, probably because of the combined effects of heat absorbed by the rock and protection
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from cooling winds by the vegetation during the day and efficient heat dissipation during the night.
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Somewhat lower temperatures during the day were reached in the vegetation and on bare rocks. On
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bare rocks temperatures were higher in the evening than at the other sites, probably because of the
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heat stored by the rocks. The variance between days was generally high (SD about 7 °C during the
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day) and highest in the vegetation (SD about 10 °C in the afternoon). Ground temperature on rocks
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with vegetation reached up to 45 °C on hot summer days. During five bad-weather days, the diurnal
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raise in ground temperature was much less pronounced (not shown).
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Fig. S1 Daily course of ground temperature at four different microtopographic sites (below rock, in
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vegetation, on bare rock, on rock with vegetation). (a) Lines are hourly means of 5 different locations
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over 33 days. (b) Lines are standard deviations and represent the variance between days
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independent of location (see Methods). The standard deviations are of residuals from a linear model
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with ground temperature as the dependent variable and location, site, hour and site × hour as
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independent variables, thus represent the variability between days independent of location. Dotted
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line = below rock, dashed line= on bare rock, solid line = in the vegetation, dot-dashed line = on rock
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with vegetation.
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Fig. S2 Contour plots of the microclimate variables (a) air temperature, (b) ground temperature, (c)
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wind speed, (d) solar radiation, (e) relief (depth), (f) vegetation height in one of the two grid-squares.
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The plane, given by the X- and Y-axes, represents the grid plane of 2 x 2 m with measurement points
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every 50 cm. The means of seven measurements were used to construct the plot. Light areas
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represent high values, dark areas low values.
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Table S1 Microclimate characterisation of the four microtopographic sites. n = 114 per
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microtopographic site and microclimate variable. The measurements were taken between 1130 and
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1630 hours on days without rain.
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Microtopographic site
Below rock
On bare rock
On rock with
vegetation
In vegetation
Ground
temperature
(°C)
Air
temperature
(°C)
Mean ± SD
16.8 ± 4.2
23.8 ± 5.5
25.4 ±7.586
22.6 ± 5.5
Min − Max
9.3 − 32.9
9.1 − 38.1
11.0 − 45.2
10.6 − 44.4
Mean ± SD
20.1 ± 3.0
20.2 ± 2.8
20.3 ± 7.6
22.3 ± 4.0
Min − Max
14.6 − 29.1
14.7 − 31.7
14.6 − 30.7
14.0 − 35.2
Wind speed
(m/s)
Mean ± SD
0.19 ± 0.29
0.60 ± 0.46
0.52 ± 0.49
0.14 ± 0.22
Min − Max
0 − 1.30
0 − 2.60
0 − 3.20
0 − 0.90
Solar radition
(W/m2)
Mean ± SD
48 ± 128
769 ± 338
667 ± 409
449 ± 325
Min − Max
1 − 772
54 − 1413
24 − 1410
19 − 1250
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Table S2 Linear mixed models testing for the effects of vegetation height and relief on wind speed,
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solar radiation, air and ground temperature in the two grid-squares (n = 350). Depth is the vertical
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distance from an imaginary horizontal plane at the highest point of the square to the measurement
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point. In each model, grid identity and date were included as random factors. * = p < 0.05, ** = p <
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0.01, *** = p < 0.001
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Estimate ± SE
t-value
CI 95 %
Sign.
Depth
0.05 ± 0.03
2.01
0.003 − 0.10
*
Vegetation height
0.10 ± 0.03
4.14
0.06 − 0.16
**
Depth×Vegetation height
-0.002 ± 0.002
-1.144
-0.005 − 0.001
Depth
-0.10 ± 0.05
-2.12
-0.20 − -0.009
*
Vegetation height
-0.46 ± 0.05
-9.62
-0.55 − -0.36
***
Depth×Vegetation height
0.006 ± 0.003
1.74
-0.001 − 0.012
Depth
-0.78 ± 2.38
-0.33
-5.14 − 3.79
Vegetation height
-4.86 ± 2.39
-2.03
-9.24 − -0.32
Depth×Vegetation height
-0.21 ± 0.16
-1.31
-0.53 − 0.07
-0.004 ± 0.004
-1.05
-0.01 − 0.004
Vegetation height
-0.03 ± 0.004
-7.08
-0.04 − -0.02
Depth×Vegetation height
0.0001 ± 0.0003
0.37
-0.0005 − 0.0006
Air temperature
Ground temperature
Solar radiation
Wind
Depth
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*
***
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Table S3 Results of generalized linear mixed models comparing the topography of points of
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ptarmigan with their corresponding control point at 5 m or at 30 m (likelihood-ratio tests, 6 separate
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models). Observation event, triplet and individual were included as random factors. Sample sizes
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were n = 42 triplets for exposition and n = 59 triplets for microtopography and slope.
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2
df
Bird versus control 5 m
20.4
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< 0.001
Bird versus control 30 m
20.4
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< 0.001
Bird versus control 5 m
32.2
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< 0.001
Bird versus control 30 m
17.6
2
< 0.001
Bird versus control 5 m
4.9
3
0.17
Bird versus control 30 m
4.1
3
0.25
p-value
Exposition
Microtopography
Slope
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