T Y B Sc. Zoology Notes: Paper IV –Animal BEhavior

By Prof. S D Rathod Dept. of Zoology B N Bandodkar College of Science, Thane, India

To live in a habitat an animal must first have access to the habitat. Once the animal has access to the

habitat it must be able to tolerate the conditions of the habitat and find the resources that it needs to

survive in that habitat. Animals must be able to tolerate at least two kinds of factors in the habitat.

These factors are abiotic factors and biotic factors. Abiotic factors are non-biological factors such as

temperature, humidity, salinity and pH to name a few. Biotic factors are biological factors such as

competition, predation, and disease. If both abiotic and biotic factors can be tolerated the animal must

also be able to find the resources that it needs to survive. Habitat is a fundamental niche which refers to

the multidimensional space with proximate factors. Habitat provides shelter, food, protection, mates,

space for breeding, feeding, resting, roosting, courtship, grooming, sleeping etc. Birds are nearly ideal

subjects for studies of habitat selection, because they are highly mobile, often migrating thousands of

miles (and in the process passing over an enormous range of environments), and yet ordinarily forage,

breed, and winter in very specific habitats. The small migrant songbirds are well known for habitat

choices -- where to feed, where to seek a mate, where to build a nest, where to stop to replenish

depleted stores of fat when migrating, and so on. Choices can be so finely tuned that often the two

sexes of a species use habitats differently. In grassland, male Henslow's Sparrows forage farther from

the nest than females; in woodlands, female Red-eyed Vireos seek their food closer to the height of

their nest (10-30 feet), and males forage closer to the height of their song perches (20-60 feet).

Animals live in competitive world. Two species or more occur in a single habitat, in which they strive for

survival, shelter, food; space etc. there may be considerable competition, predation, diseases,

allelopathic agents (antibiosis/ poisoning) in the existing habitat.

Every available space cannot play a role of habitat for all species at a time due to certain antagonistic

factors. Therefore the animals select the habitat which fulfils its niche and keeps it away from other

antagonistic factors.

I. Effect of different factors on habitat selection:

Factors like behavior of organisms, physicochemical factors, genetics, phylogeny etc. are responsible

for the habitat selection.

a. Behavior of organisms-

Different behavioral pattern of organisms make them to select a definite habitat. A species

finalizes the suitable habitat after vigorous interaction amongst other organisms.

T Y B Sc. Zoology Notes: Paper IV –Animal BEhavior

By Prof. S D Rathod Dept. of Zoology B N Bandodkar College of Science, Thane, India

i. Prey species: The predators are confined to the habitat where their prey population is

available in abundance. E.g. predatory birds are seen near the insect population.

Kingfisher prefers the habitat near ponds or lakes where fishes are abundant.

ii. Competitors: Many species having similar niche are competitors. They avoid the

competition by sharing the habitat e.g. tree pipit prefers the dense trees whereas

meadow pipit lives in the bushes of grassy areas.

iii. Allelopathic agents: Certain organisms repel

others by secreting harmful or unpleasant

chemicals to occupy the area. The intolerant

species more other places and select other

habitats. E.g. Noctiluca sp. Secret toxic chemicals

hence other zooplankton are not found in this

area. Fungi secret antibiotic keeping other micro-

organisms away from the habitat.

iv. Predators: Excessive pressure of predation may make prey species to move to other

comparatively more safe habitats. Or the prey species is eradicated due to the high

predation pressure from the areas and flourish in the other less sever habitat.

b. Physical and chemical factors- Organisms are very sensitive to the physic-chemical factors,

predominantly the temperature and moisture. The factors like temperature, moisture, light, pH,

humidity, soil texture, fire, oxygen, soil fertility, salts etc. will decide the species to be living in a

habitat. The compatible species to the existing factors will survive in a habitat. Animals select

T Y B Sc. Zoology Notes: Paper IV –Animal BEhavior

By Prof. S D Rathod Dept. of Zoology B N Bandodkar College of Science, Thane, India

the habitat of their physiological tolerance e.g. woodland deer mice select forest rather than

crop fields, because they cannot tolerate the high temperature in the field. Within the forest

they may prefer to live in large trees like oak or beech where they get more food as acorns and

beechnuts in addition to better shelter and more nest sites. Phytoplankton flourish at surface

near shore of the oceans where the ample sunlight for photosynthesis and nutrients for their

growth occur.

c. Genetic relationship- Living beings have evolved with the available environment, thus have

phylogenetic relationship. Sometimes the different species although having capacity to live in

variety of habitats they are typically confined to one of those. E.g. coal tits select only pine trees

where as blue tits select oak trees.

d. Early experience- Organisms having experience in different habitats, select the one out of

many which is best secured for their survival. This knowledge they gain from experience.

e. Microhabitats- Some small organisms like

flies, ants, termites, aphids have to select

certain microhabitat which provides them the

life commodities. E.g. Drosophila selects

habitat of high humidity. Aphids select broad

leaves on cotton wood tree where their

reproductive success is high. O’Neil (1967)

found seven spp. of millipedes in a maple

forest. All were detritivores and living in same

habitat. But detailed research revealed that

each species dominated in its own specific microhabitat, which was different from the others.

The microhabitat of each species was comprised of a particular gradient of detritus which they

preferred as compared to other species.

T Y B Sc. Zoology Notes: Paper IV –Animal BEhavior

By Prof. S D Rathod Dept. of Zoology B N Bandodkar College of Science, Thane, India

II. Model example:

No two species living in the same general habitat can occupy identically the same ecological niche.

Other example is dependent on the tradition of their behavior. Three similar species of ungulates

live in different habitats in a forest. ‘Sambar’ (dancing deer) prefers the hilly terrain and ‘chital’

(spotted deer) prefers the dense forest with large trees whereas the ‘Kalwit’ (blackbuck) selects the

open savanna in Indian forest.

Dancing Deer (Sambar) Spotted Deer (Chital)