Assessing The Habitat Suitability of Six Coniferous Forests Using Avian Assemblages At High Altitude Ecosystem

Birds are habitat specialist, i.e. often selects habitat that offers ample services such as a variety of food resources, safe breeding and less disturb sites to satisfy their needs. We aimed to ascertain the conservation status of avian assemblages inhabited in six different coniferous forests. The study employed the point count method to determine the avian assemblages in each forest type. The surveys were conducted employing the distance sampling point count method and determining the oristic composition through direct visual estimation from January 2018 to March 2019. In total, 2465 bird individuals representing 57 species and 29 families were observed in six coniferous forests. Twelve tree species, nine shrub species, and 14 grass species were identied in the forests. Except for the Streptopelia turtur (vulnerable), all bird species are listed as “least concern” according to the IUCN Red List Category and Criteria 2019–2. Notably, the relative abundance of bird assemblages among six coniferous habitats was signicantly different (F5, 293 = 22.8, p < 0.05). The CAP results reected that bird diversity indices varied coniferous forests. Strikingly, dry–temperate coniferous forest (BG) was densely populated (5.831 ± 0.694 birds•ha−1) as compared to other habitats. These ndings suggested that subtropical coniferous forests are cradles of life for a wide array of avian assemblages and hence should be declared as protected forests to enhance avian assemblages in this region. Comparison of Bird Diversity among Six Coniferous Forests: CAP analysis demonstrated that avian diversity, varied among the six coniferous forests. The highest species diversity was documented in mixed dry–temperate coniferous forest (Z), H’ = 3.625 ± 0.027 while the lowest was documented in mixed dry– temperate coniferous forest (G), H’ = 3.261 ± 0.027. Likewise, dry–temperate coniferous forest (BG) was rich in avian species (R 1 = 8.178 ± 0.031) and mixed dry-temperate coniferous forest (G) was the least preferred habitat (R 1 = 7.191 ± 0.031). Similarly, bird species were evenly distributed in mixed dry–temperate coniferous forest (K), E


Description
Forest Types  Data collection for this study was designed on the basis of (i) habitat structure, i.e., landscape, vegetation richness and density, vegetation complexity, percentage vegetation cover, and vegetation composition (e.g., trees, shrubs, and grasses); (ii) occupancy of cryptic, shy, and skulking species, such as tits, tree creepers, babblers, warblers, and chiffchaffs; (iii) availability and richness of food resources; (iv) human intrusion; and (v) areas best tted to attract bird species. This is because the vegetation composition and complexity affect the distribution and diversity of species (Souza et al., 2015). Likewise, the availability and distribution of food resources in a particular habitat in uence the bird community structure and behavior (Levinton and Kelaher, 2004 (Antongiovanni and Metzer, 2005). Each point was visited at least four times during the 15 consecutive months of the study period. Normally, the bird surveys at the 30 points were completed within 1-5 days. Efforts were made to cover all six study areas within the same month. Whenever this was not possible, we ensured that the surveys were completed in the following month.
Only sighted bird species within each point count station sampled were considered. However, some bird species were identi ed through vocal sound, and their position was determined from where the sound was heard. The birds were surveyed at each point count station for 15 min and allowed a 1 min settling time (Gregory et al., 2004). The radial distance from the bird to the observer was recorded using visual estimation. The birds were surveyed between 7:30 and 11:00 a.m. This time was most suitable to conduct the survey because most of the birds were active in foraging, perching, lea ng, and sallying activities. Moreover, to avoid the bias of weather, the survey was stopped immediately when the weather conditions were unfavorable (e.g., rain or thick mist). A radius of 30 meters around the point count was used for the bird survey. All surveys were conducted by the main author.
Vegetation Survey: Assessing the oristic composition (i.e. trees, shrubs, grasses and herbs) are key variables that re ect the territory e ciency, aesthetic beauty, and harbor the assorted bird fauna species meet their needs (Schulz et al., 2009 Species Diversity Index: The diversity is a varied and inconstant among the bird assemblages in coniferous forest. It accounts for plenitude by giving data on the irregularity and commonality of bird species. For example; Shannon's diversity index is calculated as follows: Where, H' designates diversity, S indicates the number of species, i speci es the abundance of species, N is the total number of all individuals, p i is the relative abundance of each species, and ln is the natural logarithm.
Species Richness Index: It is the number of diverse bird species in a given habitat. It moreover gives data on the homogeneity and irregularity of bird distribution and occurrence. For example; Margalef's Richness Index; Where, S is the total number of species and N is the total number of individuals in the sample.
Species Evenness Index: It is the degree of the relative plenitude of distinctive bird species in a speci c range. For example; Pielou J Evenness Index; Where, H = is the observed Shannon-Wiener index and S = is the total number of bird species in the coniferous forest.
The correlation between Bird Diversity and Vegetation Structure among Six Coniferous Forests: Pearson's correlation coe cient was applied in order to understand the effects of vegetation structure on bird diversity in the six coniferous forests.
Bird Density among Six Coniferous Forests: Determining an accurate population size is highly important to obtain the current population status of different bird species in a dwelling habitat. The bird population was determined through the DISTANCE Software (Version 7.1) by Buckland et al. (2004).
The key to distance sampling is to use the distribution of observed distances to determine the "detection function" g (y), i.e., the probability of estimating a bird at distance y. This function can then be used to ascertain the mean probability of detecting a bird given that it is within w of the point, denoted Pa. Given an estimate of Pa, bird density can be determined using the following equation: where a is the size of the covered region, n is the number of birds detected, and Pˆa (zi) is the probability of detecting the i-th bird given that it is within w of the point and has the covariate values zi (Buckland et   herbs (98.0%; 7 species), compared to the other habitats. However, vegetation composition varied habitat to habitat depending on soil depth and fertility, intensity of grazing pressure, uncontrolled rewood collection, and land-use change pattern (Table 3).    in sub-tropical coniferous forests (S), and two species in dry-temperate coniferous forest (L) were not determined due to a low number of bird detections, i.e., fewer than ve detections (Table 7).  Most bird species are habitat specialists, i.e., they utilize different layers of vegetation for foraging, shelter, and breeding purposes. Some avian species prefer the forest oor (e.g., common babblers, common quails, common hoopoe, magpie robins, blue whistling thrush, and pied bushchat), while others utilize the tree canopy, i.e., Indian paradise ycatchers, scarlet minivets, golden orioles, cinereous tits, yellow-footed green pigeon, speckled wood pigeon, streaked laughing thrush, and common rose nch (Gardner et al., 2009;Malhi et al., 2014).
Notably, the food resources among the six coniferous forests are not distributed uniformly and may vary from area to area, depending on topography, microclimate, altitude, and vegetation structure and composition. Likewise, the bird relative abundance among these six forests also varies. The highest relative abundance was detected in dry-temperate coniferous forest (BG) and the lowest was detected in mix dry-temperate coniferous forest (G). This result indicated that the birds often select an area on the basis of proximate factors, i.e., landscape, terrain, substrate, microclimate, characteristics, extent of the disturbance, predation, and occurrence of food resources. These factors determine avian community parameters such as diversity, density, and distribution.
Another reason could be that the oristic diversity shaping the forest structure in uenced the bird population structure. Blake (2007) reported that the bird relative abundance and species composition might vary due to vegetation structure and complexity.
The "highest" bird density was estimated in the dry-temperate coniferous forest (BG) as compared to the other habitats. The higher bird density in drytemperate coniferous forest (BG) was due to the occurrence of fruiting trees (e.g., Ficus carica, Morus alba, and M. nigra), shrubs (i.e., Zizihpus nummularia, Reptonia muscatencesea, Berberis lyceum, Gymnosporia royleana, Zanthoxylum alatum, and Myrtus communis), grasses, Solanum nigrum, and owering trees (i.e., Acacia modesta and Ailanthus altissima) that provide adequate food sources to harbor the denser avian population. The dark-throated thrush, blue whistling thrush, and streaked laughing thrush prefer shrubs in their search for insects, arachnids, and berries. Likewise, the red-vented bulbul, Himalayan bulbul, and white-eared bulbul often utilizes fruiting trees and shrubs for berries and grasses for insects (Brooks,  and common starlings used common g, wax apple, and barberry to consume a wide array of fruits and berries, and prey on insects, especially caterpillars. The wax apple populated degraded habitats such as forest edges and mixed vegetation for foraging, particularly on insects (including dragon ies, honeybees, grasshoppers, moths, beetles, and crickets), through sallying, gleaning, and hovering (Somasundaram and Vjayan, 2008). They mainly utilized forest edges and cultivated areas to forage on a variety of food items, i.e., fruits, lizards, rodents, and large insects.
Notably, the black francolin, common quail, and bay-backed shrike were con ned to forest edges, shrubs, and grasses, as these are a shy species with secretive behavior. Another reason may be that the forest edges provide cover from predators (Fuisz and Yosef, 1998 Kesler, 2012). Moreover, other birds, for instance, the greenish warbler, preferred to use conifer trees for foraging. During foraging, they glean in the crown to prey on midges, caterpillars, beetles, leafhoppers, bugs, wasps, moths, and spiders. However, sometimes, these birds sail in dense shrubs to catch insects on their wing (Johnson and Sherry, 2001). Likewise, the bar-tailed tree creeper also selected coniferous trees for foraging. Upon reaching the top of the conifer through progressive hops, they then y down to the base of the next tree trunk and start climbing again in a spiral fashion in their search for food (i.e., insects, caterpillars, and spiders).
Apparently, the speckled wood pigeon and rock pigeon were concentrated in fruiting trees and shrubs (i.e., common g, wind prickly ash, yellow Himalayan raspberry, and barberry) to forage for berries and eshy fruits. Likewise, the European turtle dove, oriental turtle dove, and spotted dove preferred grounds to feed on grains and seeds of grasses (e.g., pine woods drop seed, beard grass, milkweed, and wild sun ower). The variation in habitat selection and food utilization showed that habitat structure, land-use pattern, and food resources are the major driving factors that signi cantly in uence the habitat use and

Conclusions
Based on the ndings of this study, dry-temperate coniferous forest (BG) is rich in vegetation species composition and represents a highly productive habitat for a variety of avian species, compared to the other coniferous forests. The occurrence of birds re ects the forest stand structure, site productivity (food resources), vegetation composition, and distribution pattern. Furthermore, it was observed that the vegetation composition and food resources are the major driving factors affecting the habitat selection and home range of avian species. Hence, special attention should be given to the dry-temperate coniferous forest (BG) in order to maintain its high quality and productivity, which are essential for future conservation efforts aimed at harboring a high avian population. This could be that, it is dominated by broadleaf tree species; Ficus carica, Morus Alba, M. nigra, Acacia modesta and Eucalyptus camaldulensis and shrub vegetation, i.e., Reptonia muscatencesea, Berberis lyceum, Dodonaea viscosa, Zanthoxylum alatum and Myrtus communis that offer suitable foraging and safe hideout for avian species. Furthermore, the understorey vegetation is comprised of Solanum nigrum, Verbascum thapsus, Ranunculus muricatus, Polygonum aviculare Rumex dentatus and grasses like Cynodon dactylon, Heteropogon contortus, Chrysopogon fulvus and Miscanthusnepalensis that bear a variety of grains and attracted a variety of insects that is a staple diet of avian species. Furthermore, going forward, the remaining coniferous forests can be declared as protected habitats to enhance their healthy avian population.