**3. Methodology**

### **3.1 Data collection**

Data were collected from June 2015 to June 2017 mostly on breeding seasons when the squirrels are more active and easily seen. We searched for animals and *Nesting Behavior of Indian Giant Squirrel (*Ratufa indica *Erxleben, 1777)… DOI: http://dx.doi.org/10.5772/intechopen.92337*

their nests along the natural trails in the dry thorn forest. Most of the nesting trees were located through intensive searches in the area by inspecting potential nesting trees and nests. The presence of IGS and their activity provide indirect evidence of use as nest trees. The IGS nesting trees were marked with GPS coordinates and classified with identification. The quantification of nesting habitat followed methods suggested by James and Shugart [14] and subsequently by Kannan [15], Mudappa and Kannan [16], and Girikaran et al. [17]. Vegetation and nest tree parameter was quantified in circular plots of 15 m (0.07 ha) with the nest tree as the center. All the trees (GBH > 25 cm) were enumerated and GBH (Girth at Brest Height) measured. Canopy cover was visually estimated. The elevation of the nesting tree distances to the nearest road, habitation was also noted. The nest tree parameters were measured such as tree height, basal area, diameter at breast height, number of primary branches and secondary, canopy cover, canopy height, canopy width and tree status such as (dead or alive) were noted. Such parameters were also quantified in similar-sized plots located 100 m in a random direction from the nest tree, where the nearest tree of GBH > 250 cm was chosen as the centre tree and the same nest tree parameters were also taken into the account for comparison of random (non-nest) plots with nest tree plots were made to determine parameters likely to affects choice of nesting habitat by Indian Giant Squirrel. The availability and density of potential nest tree species were assessed from 16 0.25 ha (50 m 50 m) vegetation plots (2.5 ha).

#### **3.2 Statistical treatment**

Mean (M) and Standard Error (SE) was calculated to the nesting trees variables in the study area. Pearson's correlation coefficient matrix was performed to understand the variables significances among the nesting trees. Man Whitney U test was used to determine differences in 13 parameters between nest (n = 158) and non-nest (n = 250) plots. Principal Component Analysis was used to understand nest site selection. Statistical analyses were performed using *Graph Pad Prism 5 and SPSS* 17.0 statistical computer software.

## **4. Result**

only one literature was available on IGS population and nesting ecology [12]. Hence the present study was under took major objectives on (1) To find out the nesting tree preference, (2) To find out the nesting trees variables to support the IGS nesting, (3) Nesting behavior of IGS, and (4) To given an scientific recommendation for long term management and sustainable conservation of the species.

Mudumalai Tiger Reserve is one of the few areas in the country with a rich and varied terrain, flora and fauna. Mudumalai plays an important role in biodiversity conservation of especially large mammals, by offering habitat contiguity of about 3300 km2 with three other protected areas in the region, namely Nagarahole and Bandipur National Park and Wayanad Wildlife Sanctuary through forest corridors between the Western Ghats and the Eastern Ghats. The reserve was created in 1940,

and later to a further 321 km2 and 688.59km2 core zone = 321 km2 and buffer zone = 367.59 km2 which it is present extent (**Figure 1**). Champion and Seth [13] classified the vegetation type in Mudumalai as Southern Tropical dry thorn forest, Southern Tropical dry deciduous forest, Southern Tropical moist deciduous forest, Southern Tropical semi-evergreen, Moist bamboo brakes, and Riparian fringing forest.

Data were collected from June 2015 to June 2017 mostly on breeding seasons when the squirrels are more active and easily seen. We searched for animals and

*Map showing the surveyed riverine habitats in Mudumalai Tiger Reserve.*

. In 1956, it was enlarged to 295 km2

the first in southern India, with an area of 60 km2

**2. Study area**

*Rodents*

**3. Methodology**

**Figure 1.**

**38**

**3.1 Data collection**

A total of 192 nesting trees with 279 nests belonging to 19 trees species were identified as nesting trees preferences of IGS in the Mudumalai Tiger Reserve (**Table 1**). Of which *Bambusa arundinacea* was the dominant nesting grass species of the IGS (11%, n = 22) followed by *Terminalia arjuna* (10%, n = 20), *Spondias mangifera* (9%, n = 18), *Syzygium cumini* (7%, n = 14) and *Ficus benghalensis*, *Manilkara hexandra*, *Sapindus emarginata* were each 12 nesting trees (n = 6%), respectively. Among the nest, wise number of nests were recorded in the *Bambusa arundinacea* (20%, n = 56) followed by *Terminalia arjuna* (10%, n = 28), *Spondias mangifera* (9%, n = 26), *Syzygium cumini* (8%, n = 22) and *Ficus benghalensis* (6%, n = 16). There is a significant difference were observed on nesting trees preferences as well as the number of nests in a nesting tree (t = 2.539; P = 0.0184). The overall nest height of the IGS was 19.70 3.25 m and a maximum height of 34 m and a minimum height of 8 m and the nest direction shows that North East has held the number of nests (n = 137) followed by South East (n = 83), South West (n = 40) and North West (n = 19) (**Figure 2**). The nest position shows that Crown (n = 197) were contained the number of nest camper to lumb (n = 82). The nest position shows that top (n = 220) were contained the number of nests compare to the middle (n = 59). on the other hand, no nest was placed on the down position. A total of 14 variables

## *Rodents*


were collected from the nesting trees and non-nesting trees for analyzing the pref-

Fourteen variables of nest tree and centre tree of non-nest sites were measured and are given above (**Table 2**). Nest trees differed significantly from centre trees of non-nest plots, in terms of size. The height of the tree, basal area, GBH, Branch end, secondary branches, canopy length, canopy cover, and elevation were all significantly greater in nest trees than non-nest centre trees (**Table 2**). But there was no significant difference in, Branch start, branch start, and branch end distance, Primary branches, canopy width, Distance to human habitation and distances to the road between nest plot and centre trees of non-nest plots. However, there was a significant difference in

**(n = 192)**

Nest/centre tree height (m) 25.63 0.68 21.48 0.47 2750 0.40\* Nest/centre tree basal Area (cm) 423.56 19.28 389.35 14.78 2125 0.03\* Nest/centre tree girth at breast height (cm) 397.32 17.25 358.46 16.25 2091 0.00\* Nest/centre tree branch start (m) 7.35 0.29 5.46 0.37 2093 0.12 Nest/centre tree branch end (m) 23.35 0.46 19.27 0.49 2782 0.05\*

Nest/centre tree primary branches 3.68 0.19 5.16 0.13 2951 0.17 Nest/centre tree Secondary branches 42.37 1.27 44.19 0.78 2901 0.03\* Nest/Centre tree Canopy length (m) 27.53 0.68 28.32 0.83 2466 0.00\* Nest/Centre tree canopy width (m) 28.34.88 0.75 29.56 0.43 2992 0.22 Nest/Centre tree canopy cover (%) 78.32 2.35 82.34 1.36 3078 0.05\*

Nest/centre tree Distance to road (km) 9.09 0.35 8.63 0.52 3259 0.37 Nest/centre tree elevation (m) 893.68 19.84 887.37 17.39 4235 0.02\*

*\*Parameters that was significantly different between nest and non-nest plot P < 0.05 significant.*

*Characteristics of nest-site and non-nest site plots of IGS in the Mudumalai Tiger Reserve.*

i. Trees of GBH ≥ 25 cm 28.35 0.54 26.53 0.69 2833 0.05\* ii. Trees of GBH ≥ 26–75 cm 5.17 0.16 4.52 0.32 2496 0.00\* iii. Trees of GBH ≥ 76–125 cm 3.36 0.17 3.85 0.19 3612 0.35 iv. Trees of GBH ≥ 126- 175 cm 3.13 0.29 2.98 0.93 2843 0.04\* v. Trees of GBH ≥ 176–225 cm 2.38 0.59 1.87 0.53 3036 0.16 vi. Trees of GBH ≥ 226–275 cm 1.25 0.17 1.89 0.23 3314 0.65 vii. Trees of GBH ≥ 276- 325 cm 1.35 0.29 1.59 0.12 3194 0.37 viii. Trees of GBH ≥ 325 cm 1.13 0.75 1.38 0.74 2841 0.03\* ix. Trees of GBH ≥ 376–425+ cm 0.52 0.46 0.75 0.49 3217 0.04\*

**Non-nest plot (n = 250)**

9.18 0.37 10.23 0.29 3272 0.77

10.36 1.26 11.12 0.18 3298 0.54

*U P < 0.05*

large tree density (GBH ≥ 25 cm, GBH ≥ 26–75 cm, GBH ≥ 126–175 cm and GBH ≥ 326–375 cm) between the nest and non-nest plots (**Table 2**).

erences of IGS nesting in the study area (**Table 2**).

*DOI: http://dx.doi.org/10.5772/intechopen.92337*

*Nesting Behavior of Indian Giant Squirrel (*Ratufa indica *Erxleben, 1777)…*

**Variables Nest plot**

Nest/centre tree branch start and branch end

Nest/centre tree Distance to human

distance (m)

habitation (km)

Tree density/ha

**Table 2.**

**41**

#### **Table 1.**

*Nesting tree preference of IGS in the Mudumalai Tiger Reserve.*

**Figure 2.** *Nest direction in nesting trees in Mudumalai Tiger Reserve.*

*Nesting Behavior of Indian Giant Squirrel (*Ratufa indica *Erxleben, 1777)… DOI: http://dx.doi.org/10.5772/intechopen.92337*

were collected from the nesting trees and non-nesting trees for analyzing the preferences of IGS nesting in the study area (**Table 2**).

Fourteen variables of nest tree and centre tree of non-nest sites were measured and are given above (**Table 2**). Nest trees differed significantly from centre trees of non-nest plots, in terms of size. The height of the tree, basal area, GBH, Branch end, secondary branches, canopy length, canopy cover, and elevation were all significantly greater in nest trees than non-nest centre trees (**Table 2**). But there was no significant difference in, Branch start, branch start, and branch end distance, Primary branches, canopy width, Distance to human habitation and distances to the road between nest plot and centre trees of non-nest plots. However, there was a significant difference in large tree density (GBH ≥ 25 cm, GBH ≥ 26–75 cm, GBH ≥ 126–175 cm and GBH ≥ 326–375 cm) between the nest and non-nest plots (**Table 2**).


#### **Table 2.**

**S.No Scientific name of the nesting trees**

*Rodents*

1 *Bambusa arundinacea* (Grass species)

**Table 1.**

**Figure 2.**

**40**

*Nesting tree preference of IGS in the Mudumalai Tiger Reserve.*

*Nest direction in nesting trees in Mudumalai Tiger Reserve.*

**Number of nesting trees**

 *Terminalia arjuna* 20 10 28 10 *Spondias mangifera* 18 9 26 9 *Syzygium cumini* 14 7 22 8 *Ficus benghalensis* 12 6 16 6 *Manilkara hexandra* 12 6 14 5 *Sapindus emarginata* 12 6 12 4 *Ailanthus excelsa* 10 5 12 4 *Terminalia bellirica* 10 5 10 4 *Acasia leucophloea* 8 48 3 *Schleichera oleosa* 8 48 3 *Tamarindus indica* 8 4 14 5 *Albizia lebbeck* 7 47 3 *Terminalia crenulata* 7 4 10 4 *Cassine glauca* 6 3 12 4 *Pongamia pinnata* 6 38 3 *Ficus mollis* 5 37 3 *Ficus microcarpa* 4 26 2 *Filicium decipiens* 3 23 1 Total 192 279

**Relative abundances of the nesting trees %**

**Number of nests**

22 11 56 20

**Relative Abundances of the nest in nesting trees %**

*Characteristics of nest-site and non-nest site plots of IGS in the Mudumalai Tiger Reserve.*

The principal component analysis (PCA) was carried out using the nest site characteristics data from all the nests of IGS observed (n = 158). **Table 3** shows Pearson's correlation matrix between the 14 variables.

PCA extracted three principal components that elucidated 87.12% variability (**Table 4**). The first component explained 39.02% variability that gives details of seven nest tree variables such as tree height, Branch Start, Branch End, Branch Start and Branch End Distance, Canopy Width, Distance to human habitation and Distance to Road in the plot and that were positively correlated with the first component. High values on the first component corresponding to the tallness of nest trees, Branch Start, Branch End, Branch Start and Branch End Distance, Canopy Width. Thus, the first component represents, with increasing values, the size of the nest tree and tallness will also increase. The first component was also positively correlated to Distance to human habitation and Distance to Road variable, which indicates, with increasing values, greater distance to human habitation and roads. The second component explained 29.07% variability that explained five nest tree variables such as basal area, GBH, Primary Branch, Secondary Branch and Canopy Length (**Table 4**). High values on the second component correspond to a basal area GBH, Primary Branch, Secondary Branch and Canopy Length. Thus, the second component also represents, with increasing values, the size of the nest tree and basal area and branch structure of the tree will also increase. The third component explained 11.68% of the total variance and was related to Canopy cover and human habitation. The fourth component explains 7.35% of the total variance and was related to Canopy cover and Elevation (**Table 4**).

A total of 24 potential nest tree species of IGS that occurred at the study area was identified based tree genera or species those that generally attain a large tree size (**Table 5**). Of these only 19 species were used for nesting by IGS in the Mudumalai Tiger Reserve. All of these trees were emergent, large girth trees and are relatively more common than other species; in fact,*Terminalia arjuna* was the most common tree species among these. The overall occurrence of *Terminalia arjuna* was 29.3 trees per ha and 10.4 per ha for trees of GBH ≥ 250 cm which were recorded in the 146 0.25 ha plots during the study period (**Table 5**). Density of large trees (GBH ≥ 250 cm) species *Alianthus excelsa* 8.91 per ha recorded in the 146 0.25 ha plots and *Pongamia pinnata* 5.89 per ha, *Manilkara hexandra* 4.40 per ha, *Schleichera oleosa* 3.46 per ha and *Spondias mangifera* 2.46 per ha recorded in the 146 0.25 ha plots. According to the tree size, the overall availability of the species was an important factor in the nest tree selection by Indian Giant Squirrel. In the study plots covering 36.5 ha, the overall availability of trees GBH ≥ 250 cm was 14.75 per ha (56.56 trees) (**Table 5**).

### **5. Discussion**

Preference for nesting trees could depend on factors such as access to nesting material and food, nest safety and the branching pattern of the tree species. A total of 18 tree species and one grass species were recognized as nesting trees of IGS in the Mudumalai Tiger Reserve. Of which *Bambusa arundinacea* (grass species) was dominant for nesting of the IGS (11%, n = 22) followed by *Terminalia arjuna* (10%, n = 20), *Spondias mangifera* (9%, n = 18), *Syzygium cumini* (7%, n = 14). The previous study reported that in this region a total of 15 tree species were utilized for nesting purposes by IGS of which *Spondias mangifera* and *Schleichera oleosa* tree species were most preferable tree species for nesting [12]. The high preference for *Bambusa arundinacea and Terminalia arjuna*, *Spondias mangifera* and *Syzygium cumini* which are found mostly along rivers and streams could be due to their dense

**H**

**43**

**H** **BA**

**DBH**

**BS** **BE** **BSBED**

**PB** **SB**

**CL**

**CW**

**CC**

**DHH**

**DR** **ELEV** *Significant at p < 0.05.*

*\*Positive correlation.* *\*\*Negative correlation.*

**Table 3.** *Pearson's correlation*

 *coefficient matrix between nesting tree variables, by IGS in the Mudumalai*

 *Tiger Reserve.*

0.224

0.052

0.054

 0.154

 0.176

 0.200

0.153

 0.177

 0.114

 0.224

0.114

 0.216

 0.254

 1

0.602\*

 0.369

 0.436

 0.481\*

 0.564\*

 0.596\*

 0.269

 0.539\*

 0.360

 0.623\*

 0.056

 0.842\*

 1.000

0.488\*

 0.245

 0.376

 0.441

 0.469\*

 0.511\*

 0.136

 0.405

 0.187

 0.476

 0.691\*

 1.000

0.551\*\*

 0.292

 0.117

0.341

0.518

0.484\*\*

0.141

 0.256

0.119

0.575\*\*

 1.000

0.862\*

0.123

 0.025

 0.501

 0.825\*

 0.971\*

 0.292

 0.056

 0.256

 1.000

0.053

 0.785\*

 0.738\*

0.318

0.126

 0.151

 0.886\*

 0.612\*

 1.000

*Nesting Behavior of Indian Giant Squirrel (*Ratufa indica *Erxleben, 1777)…*

*DOI: http://dx.doi.org/10.5772/intechopen.92337*

0.029

 0.700\*

 0.593\*

0.044

0.087

0.050

 0.570\*

 1.000

0.012

 0.692\*

 0.635\*

0.239

0.047

 0.207

 1.000

0.876\*

0.177

 0.019

 0.546\*

 0.862\*

 1.000

0.992\*

0.272

 0.000

 0.884\*

 1.000

0.866\*

0.269

 0.019

 1.000

0.014

 0.901\*

 1.000

0.241

 1.000

1.000

 **BA**

 **DBH**

 **BS**

 **BE**

 **BSBED**

 **PB**

 **SB**

 **CL**

 **CW**

 **CC**

 **DHH**

 **DR**

 **ELEV**


**Table 3.** *Pearson's correlation coefficient matrix between nesting tree variables, by IGS in the Mudumalai Tiger Reserve.*
