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

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

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

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

plots and *Pongamia pinnata* 5.89 per ha, *Manilkara hexandra* 4.40 per ha,

(GBH ≥ 250 cm) species *Alianthus excelsa* 8.91 per ha recorded in the 146 0.25 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

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

Pearson's correlation matrix between the 14 variables.

*Rodents*

related to Canopy cover and Elevation (**Table 4**).

ha (56.56 trees) (**Table 5**).

**5. Discussion**

**42**


*Rodents*

**Table 4.** *Summary statistics of principal component analysis.* canopy cover, and higher canopy height and contiguity that could offer better

A total of 192 nesting trees harboring 279 nests in an average of 2.66 nesting trees per km and 3.87 nests/km in a 72 km transect. In the previous study stated that a total of 83 nests were located along 54.2 km transects, giving an encounter rate of 1.5 nests/km of transects [12]. Previously the number of nests was reported in the moist deciduous forest [18] but in this study, I recorded the high number of nests in

habitat for IGS in the environment. The assortment of nesting sites in most of the arboreal animal communities was seen in the riparian ecosystem, since of the diversity of plant species and tallness of the trees establish in these kinds of habitats and also accessibility of water for thermoregulation and humidity the stage of the

The nesting tree characters shows that the average height of the nesting tree and DBH and Trunk size and canopy had a very good percentage. Among the 19 nesting

's evident that riverine patches afford good

, *Spondias mangifera*

protection and escape from predators.

**S.No Scientific name Height**

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

1 *Acasia leucophloea*

2 *Alianthus excelsa*

3 *Albizia lebbeck*

4 *Cassine glauca*

5 *Schleichera oleosa*

6 *Spondias mangifera*

7 *Syzygium cumini*

8 *Terminalia arjuna*

9 *Terminalia crenulata*

10 *Ficus benghalensis*

11 *Ficus microcarpa*

13 *Filicium decipiens*

14 *Manilkara hexandra*

15 *Sapindus emarginata*

16 *Tamarindus indica*

17 *Terminalia bellirica*

18 *Pongamia pinnata*

19 *Butea monosperma*

20 *Chloroxylon swietenia*

22 *Ficus religiosa*

**Table 5.**

**45**

23 *Givotia rottleriformis*

24 *Holoptelea integrifolia*

21 *Ficus racemosa* 10

12 *Ficus mollis* 11

**(m)**

8

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

5

8

8

4

2

6

9

4

8

8

8

8

5

4

6

8

5

6

*Potential nest tree species, tree characteristics, and availability of IGS in MTR.*

6

**DBH Overall tree density/ha**

–28 93.44 8.91 0.26

7–28 191.8 2.33 0.73

–25 228.61 2.46 0.93

–28 175.75 1.40 0.47

–34 188.64 29.3 10.4

–26 107.36 0.80 0.17

–24 296.15 1.86 0.53

–21 94.66 2.86 0.06

–26 120.71 0.53 0.06

–20 134.17 1.13 0.13

7–28 150.73 4.40 0.6

–18 92.56 1.13 0.13

–23 215.23 0.45 0.12

–18 136.21 5.89 0.03

–23 286.12 0.34 0.05

–22 254.85 0.19 0.06

–12 154.36 0.75 0.02

–26 96.57 1.2

– 75.1 2.06

–18 114.52 3.46

–16 96.5 0.86

–15 142.27 0.26

–16 112.65 0.58

–13 116.57 0.68

**Tree density/ha**

0

0

0

0

0

0

0

≥ **250 cm)**

**(GBH**

*…*

dry thorn forest riverine patches, it

enormous role for assortment of this habitat [19].

trees *Bambusa arundinacea* (Grass species),*Terminalia arjuna*


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

#### **Table 5.**

*Potential nest tree species, tree characteristics, and availability of IGS in MTR.*

canopy cover, and higher canopy height and contiguity that could offer better protection and escape from predators.

A total of 192 nesting trees harboring 279 nests in an average of 2.66 nesting trees per km and 3.87 nests/km in a 72 km transect. In the previous study stated that a total of 83 nests were located along 54.2 km transects, giving an encounter rate of 1.5 nests/km of transects [12]. Previously the number of nests was reported in the moist deciduous forest [18] but in this study, I recorded the high number of nests in dry thorn forest riverine patches, it's evident that riverine patches afford good habitat for IGS in the environment. The assortment of nesting sites in most of the arboreal animal communities was seen in the riparian ecosystem, since of the diversity of plant species and tallness of the trees establish in these kinds of habitats and also accessibility of water for thermoregulation and humidity the stage of the enormous role for assortment of this habitat [19].

The nesting tree characters shows that the average height of the nesting tree and DBH and Trunk size and canopy had a very good percentage. Among the 19 nesting trees *Bambusa arundinacea* (Grass species),*Terminalia arjuna*, *Spondias mangifera*

**Variables**

**44**

Height

BA GBH Branch Start

Branch End Branch Start and Branch End Distance

Primary Branch

Secondary Branch

Canopy Length

Canopy Width

Canopy Cover

Distance to Human habitation

Distance to Road

Elevation

Eigen value

% Variance explained

% Cumulative

*r- Pearson correlation coefficient, c- Factor Score coefficient*

*\* Correlation*

**Table 4.**

*Summary statistics of principal component*

 *analysis.*

 *significant at P < 0.05*

 explained

**Communality**

0.978 0.923 0.794 0.792 0.968 0.884 0.916 0.784 0.965 0.918 0.815

0.801 0.918 0.855

0.316

 0.054

> 5.85

39.02 39.02

0.845\*

 0.144

 0.287 0.039

4.36 29.07 68.10

0.009

 0.309

 0.176

> 1.75

11.68 79.77

 0.812\*

 0.736

1.10

7.35

87.12

 0.066

 0.331

 0.189

 0.106

 0.096

0.714\*

 0.122

 0.205

 0.047

 0.459\*

 0.256

 0.219

 0.198

0.409

0.070

 0.373

 0.085

 0.639\*

 0.365

 0.618\*

 0.288

0.876\*

 0.150

0.303

 0.052

 0.813\* 0.211

0.048

0.323

0.184

0.053

0.048

 0.187

0.328

 0.056

 0.776\*

 0.178

 0.242 0.424

0.242

0.178

0.162

 0.138

0.292

 0.050

 0.722\*

 0.166

0.553

0.316

 0.056 0.129

0.117

 0.050

0.852\*

 0.146

0.285

0.065

0.270

0.154

 0.063

 0.057

0.860\*

 0.147

0.454

0.104

0.053

0.030

 0.142

 0.129

0.700\*

 0.120

0.323

 0.055

 0.798\* 0.452

0.104

 0.235

 0.134

 0.208

 0.188

 0.183

0.060

0.034

 0.224

 0.203

0.134

 0.023

 0.947\*

 0.217

0.006

0.004

 0.087

 0.079

0.895\*

 0.153

0.408

0.094

0.074

0.042

 0.076

 0.069

**PC1**

**PC2**

**PC3** **rcrcrcrc**

**PC4**

*Rodents*

and *Syzygium cumini* trees contained the tallest height as well as DBH and Trunk size and canopy cover. The high preference for *Bambusa arundinacea*,*Terminalia arjuna*, *Spondias mangifera* and *Syzygium cumini* which are found mostly along rivers and streams, could be owing to their dense canopy cover, and higher canopy height and contiguity that could proffer better guard and escape from predators. Such prejudiced assortment towards matured trees with greater canopy contiguity could make easy group to and from the nest in all instructions, the main benefit to escape from predators and to move to other parts of the home range for foraging and other activities as reported by Ramachandran [8] Datta and Goyal [20] and Parathan [11]. Mudumalai Tiger Reserve holds a good population of this endemic mammalian species in India. The sanctuary is a natural mosaic of different forest types and effective conservation management could have a positive, long-lasting impact on

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

the population of the Indian giant squirrel.

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

**Author details**

**47**

Samson Arockianathan

Bombay Natural History Society, Mumbai, Maharashtra, India

\*Address all correspondence to: kingvulture1786@gmail.com

provided the original work is properly cited.

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

The canopy length and width, as well as branch start and branch end, was very good in *Terminalia arjuna*, *Spondias mangifera* and *Syzygium cumini*, as well as these trees, hold most numbers of nest compare the other nesting trees. These results coupled with the results of nest tree characters show that the squirrels prefer the largest trees available and highest locations on the trees within their home range to build their nests. The selection is however strongly influenced by tree species and their physical characteristics including canopy contiguity as reported elsewhere [20] for the species. Prakash et al. [21] stated that the canopy length width is an important factor for choosing a nesting tree it provides shelter as well as protection.

This study found that a single tree holds a maximum five numbers of nest and minimum one nest and the average height of the nesting trees was 24.4 m. There were more than one or two nests in a single tree [18]. The tree species with multiple numbers of nests were *Terminalia arjuna*, *Spondias mangifera* and *Sizizyum cumini.* Kumara and Singh [22] sighted the Indian giant squirrel mostly at a height of 16 to 20 m in moist forests and 11 to 15 m in dry forests. We observed the Indian giant squirrel nesting on a large variety of the tree species (n = 37) in Karlapat wildlife sanctuary. Kanoje [23] also reported the use of a large variety of tree species (n = 30) for nesting in Sitanadi wildlife sanctuary, India. The nests were not built on the highest possible branch, as the squirrels sought cover above the nest. Such cover might help avoid direct heat from the sun and serve as hiding—place from birds of prey [10]. Among the 279 nests most of the nests were facing the northeast direction this is the influence of the sunlight effects plays a huge role in the nest position [24]. The maximum nests' width and length 70 and 35 cm, respectively. The nest condition, as well as length and width, play an important role in utilization as well as the care of young ones [7]. A nest was mostly located in the top (79%) and Middle (21%) of the canopy these results coupled with the results of nest tree characters show that the squirrels prefer the largest trees available and the highest locations on the trees within their home range to build their nests. The variety is however strongly predisposed by tree species and their physical characteristics as well as canopy contiguity as recorded in a different place [20] for the species.

## **6. Conclusion**

Mudumalai Tiger Reserve faces severe pressure from the collection of non–timber forest products (NTFP) collection. Fruits of *Spondias mangifera* and *Tamarindus indica* are among the top NTFP collections and *Bambusa arundinacea* is highly utilized by local people for fences and home construction activities etc. which are also the preferred nesting trees of the Indian giant squirrel. The threats to this squirrel population in Mudumalai Tiger Reserve are immediate and visible. The results of this study support the need to implement the following conservation measures for the Indian giant squirrel: prevention of cutting *Bambusa arundinacea* of the preferred nesting species and regular monitoring of NTFPs; prevention of forest fires and mitigation of heavy grazing to allow regeneration of trees.

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

Mudumalai Tiger Reserve holds a good population of this endemic mammalian species in India. The sanctuary is a natural mosaic of different forest types and effective conservation management could have a positive, long-lasting impact on the population of the Indian giant squirrel.
