We found that the pythons could maintain their body temperature higher than air temperature in refugia during the cold spell (the record in 17 December 2010, air: 4℃; PM05: 23.1℃; PM13: 17.6℃; PM16:
21.7℃). We picked the body and the air temperature data during one of the most severe cold spell in 2010 winter (14 December 2010 to 20 December 2010, Fig. 13), and compared to most severe cold spell occurred in Florida, 2010 winter (Mazzotti et al. 2010). We found an interesting phenomenon: the body temperature from native pythons was stable when air temperature was reducing; on the contrary, the body temperature from invasive python fluctuated with air temperature, and finally resulted to mortality at that cases.
The most debatable issue about Burmese pythons in the United States is whether the invasive pythons could disperse to other States north from Florida. Several studies proposed that the pythons will invade most States in south of America (Rodda et al. 2009; Rodda et al. 2011). However, some others proposed the reverse due to the severe limitation by ecological constraints (Pyron et al. 2008). Because pythons are strongly limited to the small area of suitable environmental conditions, the predicted distribution of the python will be strongly limited by their microhabitat availability (Pyron et al. 2008). It showed the physical factor in environment was possibly not the most important part of Burmese python distribution. Although the warm climate of the Florida probably makes underground shelter unnecessary, microhabitats that provide retreats during cold winter weather may be a limiting factor in cooler
21
regions (Dorcas and Willson 2011). In our research, we found python used refugia to avoid extreme body temperature in winters. This result demonstrated that the suitable habitat can protect pythons from cold-induced mortality. It’s possible that pythons expanding north of their current in South Florida will survive only in regions where large underground retreats exist (Dorcas and Willson 2011).
In conclusion, the Burmese python in Kinmen showed prominent seasonal variation in movement pattern, home range, and habitat use, and temperature regulation. Seasonal habitat use could effectively regulate body temperature, avoided hyperpyretic situation from sunlight in summers and resisted harm from low temperature in winters. Although with limited sample size, this study provides the very first ecological information for this species, which is a focal target both in biological conservation and invasive managements.
22
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Table 1. Gender, morphometric data and tracking details of each python.
Python number Sex SVL (cm) Weight (kg) Home range (ha) Tracking days Number of location Tracking period
PM01 F 275.0 9.85 113.3 41 70 25 May 2010-11 September 2010
PM05 M 214.0 7.12 246.3 69 137 10 July 2010-15 June 2011
PM12 F 223.0 8.22 22.4 20 30 25 May 2010-26 October 2010
PM13 M 186.3 4.22 113.4 15 31 27 October 2010-18 July 2011
PM15 F 321.5 17.15 677.1 269 537 14 April 2011-7 May 2012
PM16 F 186.0 3.94 222.1 27 53 27 October 2010-21 July 2011
PM17 F 300.5 24.74 136.5 210 419 14 April 2011-28 January 2012
PM21 F 221.5 8.54 65.4 31 61 14 August 2012-25 February 2013
PM23 M 203.5 5.39 309.3 154 306 27 August 2011-22 July 2012
PM28 M 206.0 5.10 768.1 169 334 11 August 2011-19 July 2012
PM30 F 311.0 21.60 85.1 62 124 27 August2011-28 November 2011
PM35 M 294.0 19.58 892.7 66 130 2 February 2012-2 December 2012
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Table 2. Home range size (hectare) of the pythons in the four seasons.
Python number Spring Summer Autumn Winter
PM01 - 113.3 - -
PM05 52.7 - - -
PM12 - - 22.5 -
PM13 - 14.9 8.4 -
PM15 5.1 212.8 164.7 5.9
PM16 - 146.4 - -
PM17 0.1 107.4 9.7 0
PM21 - - 39.2 0.2
PM23 30.6 - 75.4 21.4
PM28 12.0 29.8 487.1 0.7
PM30 - - 81.7 -
PM35 8.1 734.8 46.8 0.7
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Table 3. Dunn’s test values on daily movements,
indicated significant difference between two seasons.
i
Summer Autumn Winter Summer Autumn Winter
Spring 891.65 411 89.93 87.74 101.42 68.26 14.49 154.04
Summer 959.91 496 - 83.31 97.62 - 53.77 222.30
Autumn 906.14 555 - - 95.60 - - 168.53
Winter 737.61 310 - - - -
29
Table 4. Macrohabitat usage of the Burmese python in the four seasons.
Spring Summer Autumn Winter
Artificial habitat 24 0 10 15
Planted forest 110 10 74 92
Secondary forest 99 319 215 76
Wetland 0 172 110 0
Agricultural land 154 118 154 151
Granitic woodland 68 26 10 90
Table 5. Adjusted standardized residuals tests of macrohabitat use in the four seasons. All absolute values over 2 indicated significant differences between the observed and the expected values.
Spring Summer Autumn Winter
Granitic woodland 4.737 -5.499 -7.274 8.896
Artificial habitat 4.688 -4.721 -1.099 1.599
Wetland -9.502 11.826 4.732 -9.328
Secondary forest -6.141 10.095 2.203 -8.404
Planted forest 7.401 -10.750 -0.592 4.794
Agricultural land 3.417 -6.302 -0.402 3.328
30
Table 6. Microhabitat use of the Burmese python in the four seasons.
Spring Summer Autumn Winter
in water 0 169 91 0
in cave or
burrow 102 49 99 283
in or on log and
litter 61 91 91 3
in grassland 138 179 203 36
in shrub 86 109 67 11
total 387 597 551 333
Table 7. Adjusted standardized residuals tests of microhabitat use in the four seasons. All absolute values over 2 indicated significant differences between the observed and the expected values.
Spring Summer Autumn Winter
in shrub 4.758 3.055 -1.943 -6.446
in grassland 2.848 0.142 4.327 -8.345
in or on log and litter 1.694 1.817 2.766 -7.303
in cave or burrow -1.065 -13.333 -6.541 25.166
in water -8.884 12.314 2.097 -8.095
31
Table 8. Dunn’s test value of canopy cover of the perching sites,
indicated significant difference between two seasons.
i
Summer Autumn Winter Summer Autumn Winter
Spring 888.84 366 86.09 87.08 96.90 72.21 191.92 177.49
Summer 961.05 499 - 80.27 90.83 - 264.13 249.70
Autumn 696.92 473 - - 91.77 - - 14.14
Winter 711.35 306 - - - -
32
Table 9. The records and analytic values of air temperature and python body temperature during daytime and nighttime in all seasons.
Air temperature (means ± SE)
Body temperature
(means ± SE) n t d.f. p-value Analysis method
Spring daytime 21.47±4.45 25.40±5.46 4 -17.72 298 <0.0001 Pair-t test
Summer daytime 29.62±3.07 29.05±2.00 5 2.61 358 0.029 Pair-t test
Autumn daytime 26.97±3.46 26.24±2.78 5 548 275 0.68 Wilcoxon Signed Rank test
Winter daytime 15.97±4.03 20.87±4.09 3 -15976.5 269 <0.0001 Wilcoxon Signed Rank test
Spring nighttime 16.64±4.05 21.71±3.79 4 -22262 299 <0.0001 Wilcoxon Signed Rank test
Summer nighttime 26.05±1.76 28.38±2.01 5 -31079 358 <0.0001 Wilcoxon Signed Rank test
Autumn nighttime 22.35±3.61 25.10±2.50 5 -17910.5 276 <0.0001 Wilcoxon Signed Rank test
winter nighttime 11.10±3.03 19.72±2.94 3 -18291.5 269 <0.0001 Wilcoxon Signed Rank test
33
Table 10. The home range (MCP method) of Burmese python compared to other snakes.
Species Maximum home range (ha) Citation
Python bivittatus bivittatus
892.7 This studyCrotalus horridus
207.4 Macartney et al. 1988Morelia spilota spilota
198 Slip and Shine 1988aMorelia spilota mcdowelli
124.16 Shine and Fitzgerald 1996Pseudechis porphyriacus
46 Shine 1987Lampropeltis getula getula
28.2 Wund et al. 2007Hoplocephalus bungaroides
11.43 Webb and Shine 199734
Fig. 1. Numbers of Python bivittatus bivittatus records from local newspapers compared to numbers of military forces (in numbers of soldiers) on Kinmen Island over larger (A) and smaller (B) time scales.
10
1950 1960 1970 1980 1990 2000 2010
100,000
2000 2002 2004 2006 2008 2010
8
R e c o rd s o f p y th o n s R e c o rd s o f p y th o n s M il it a ry f o rc e (# o f s o ld ie rs )
10
35
Fig. 2. Phylogeny and gene genealogy among Python bivittatus bivittatus populations from Kinmen, Fuzhou (China), and Vietnam. (A) A maximum-likelihood tree of the concatenated dataset; (B) a minimum-spanning network of the mitochondrial cytochrome
b gene; (C) a minimum-spanning network of the mitochondrial cytochrome oxidase
subunit I (COI) gene.36
Fig. 3. Home range size of Burmese pythons in Kinmen island during the tracking period. There was no significant difference in home range size between males and females during the experimental duration (t=-2.00, d.f.=10, p=0.07). (a) Male python home range;
456.96±342.96 hectare, n=5; (b) female home range; 188.84±224.22 hectare, n=7.
(a) (b)
37
Fig. 4. Home range size of all pythons in different seasons (spring: 18.10±19.92, n=6; summer:
194.18±247.69, n=7; autumn: 103.94±151.62, n=9; winter: 4.84±8.43, n=6). The home range area of the pythons was significantly different among seasons (F=10.57, d.f.=(3,24), p<0.0001).
Different letters indicate significant differences between seasons, a > b > c; least significant difference post hoc comparisons.
0 50 100 150 200 250 300 350 400 450 500
Spring Summer Autumn Winter
H o me ra n g e o f e a ch p yt h o n (h a ) a a
b b
c c
38
Fig. 5. The moving distance per day (m/day) showed significant difference among seasons (Kruskal-Wallis: χ2=62.56, d.f.=3, p<0.0001, spring: 16.75±56.21, n=6; summer: 54.50±132.90, n=6; autumn: 33.45±104.52, n=8; winter: 7.30±30.73, n=5). Different letters indicate
significant differences between seasons, a >b; least significant difference post hoc comparisons.
0 20 40 60 80 100 120 140 160 180 200