Habitat selection varies according to species but not all habitat selection involves ‘territory’. Many species remain itinerant, at least to some extent. Albatrosses, as is legendary, are eternal wanderers, the seas being their true home. They may spend years flying at sea, rarely even landing on the water’s surface. Only for breeding purposes do they come back to land and reunite with a lifelong breeding partner. Other bird species are true nomads that never call a plot their own, choosing a nesting site that they will defend just for the period of raising their young. Then there are the seasonal travellers, the birds that migrate across vast expanses of land and sea. A wide variety of species belongs in this category, including shore-birds, water birds, raptors, songbirds and even very small passerines.
Birds may stay in one place or move into a home range on a seasonal basis. The latter are said to be semi-nomadic. Most parrots are seminomadic: they go where they can find seeds. Fruit-eating birds, likewise, go to where the trees are fruiting, and this may be sporadic and require quite long-distance travel. Semi-nomadic birds may also be found in tropical rainforests around the world.
A very large group of avian species, however, is territorial and sedentary, meaning that they choose an area and remain in it permanently for as long as life circumstances permit. Territorial behaviour is of great interest in all living organisms. It is found in invertebrates, fish, amphibians, reptiles, birds and mammals—in short, in most living organisms. Territoriality involves a range of behaviours that has been established in each species over evolutionary time.
Countless researchers have investigated territoriality. Classic studies are concerned with the biological significance of the territories of birds. The questions of territory size, shape, choice and neighbourhood have all featured in research although the fascination with defence and aggression has probably outweighed all other aspects of territoriality. Even so, the processes by which territory is actually established and secured are still not well understood.
Establishing a territory can be hard work, requiring continuous vigilance to defend and maintain it. There may be a different set of problems in the centre of a territory as against the fringe of it, called the centre-edge effect, and the territory may never be secure from takeover by intruders. Fighting or vigilance flying requires a continuous high output of energy and this raises the question of what advantage territoriality can confer over semi-nomadic or highly nomadic living. Most birds can fly and hence could take advantage of their mobility. By opting to remain in one territory, they voluntarily forfeit some of the advantages of being able to fly. Presumably, flight enables birds to choose a territory after surveying possible sites elsewhere. The advantages and disadvantages of one lifestyle over another must balance out. For example, territoriality in its broadest sense is a form of resource partitioning that secures a constant supply of food. Territoriality may thus be the best way of surviving in one locality but not in another.
With their unique physical features and diverse adaptive behaviours, birds present us with the continual challenge of unravelling their complexities and diversity. A hundred years ago, people were not fully aware that birds have very specialised needs and that everything we humans do can have a detrimental effect on them. Now that we know this we are in a position where we can actively plan the prevention of any further decline of bird numbers and species. To do this well, we need to study their behaviour. Without this knowledge, we cannot begin to be effective protectors of their needs.
A Part of Introduction The Amazing Book of Gisela Kaplan & Lesley J. Rogers “BIRDS, THEIR HABITS AND SKILLS.
omkicau.com: This article’s dedicated for bird keeping purposes.
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