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Here is an essay on the ‘Census of Species’ for class 9, 10, 11 and 12. Find paragraphs, long and short essays on the ‘Census of Species’ especially written for school and college students.
Essay # 1. Objective of Census:
The objective of census is not only to ascertain the number of the particular species but also to get the knowledge about its density, sex- ratio (male-female ratio), age-ratio and adult-young ones ratio; so that on this basis the indication of the health, increment or decrement of that particular species-population may be obtained.
For instance; if after the census of a species, the data was procured like one year old male and female plus young ones as 55%, it is clear that the future of this species is very good, means there will be proper propagation in the population in coming years because this class (one year old male and female plus young ones) will be adult in the coming years; but on the contrary, if such data is 20%, it is not good sign for future of the species.
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Hence, census plays very important and key role in wildlife-management-techniques. It may be defined as “the enumeration or counting of a particular species in a particular area/habitat in a-particular time as well as dividing them into age and sex classes etc. is called wildlife census”. It is also called as Wildlife-inventory/Species-inventory/Population-estimation/Game-survey.
The main objective of the census is to find out the density of the population of the species and to procure basic data for its management. Wildlife-population is not always static. Its number increases/decreases at different places means the number of the same species varies from place to place. It also changes yearly and even in different seasons of the year.
Hence; only one census is not fully informative from its management point of view, and that is why, census should be regular and periodical and only then it should be analyzed so that the number of the species-population may be accurately obtained in different seasons and situations.
Though census is the primary step of the conservation and management of the wild animals, it is a tuft and hard work because the animal-population is scattered in the whole area/habitat due to few in number and also the animals try to hide themselves.
Essay # 2. Importance of Census:
(i) It gives an idea of population of particular species of a particular habitat at a particular time.
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(ii) It gives the sign that whether any species is facing extinction-threshold or not. It means census ascertain the status of population of a species telling about it to be surplus/rare/endangered/extinction-threshold etc.
(iii) Census is one of the major parts of the wildlife conservation and, thus, it may be said that census is the key of wildlife-management-techniques.
(iv) It gives us an idea of individual population, whether they are increasing or decreasing, and if so, at what rate?
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(v) It also gives the idea of species-population in different seasons and situations and years which are essential from management point of view.
(vi) It helps in the scientific-management of wild animals.
(vii) Census also helps in finding out the growth-rate, longevity, and movement etc. of that species.
(viii) It also gives the idea of carrying-capacity of the habitat for the concerned species.
(ix) If there is estimation of every year population, the graph of the species numbers against years can be plotted and, thus, trend of growth can be easily estimated.
(x) The growth-rate for a particular period of a year can be found out.
(xi) The growth rate(r) can be estimated for a particular time (t) by the help of the formula like rt = log t1 – log t0 (t = t1 year – t0 year), and if “r” is known then particular time “t” can also be calculated.
(xii) The area-wise or habitat-wise density can be displayed on graph, table, map etc. to take valuable guidelines for applying in wildlife techniques/management.
(xiii) Since in census, there are descriptions of area, date, time, census method applied, sampling percentage etc.; it is very valuable basis and documents helping in finding out the methodologies and techniques to protect and propagate the particular species.
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The scientific management of the animal-population of an area calls for an estimate or census of the number of animal that the area can support. Any removal or introduction of individuals of a species must be preceded by a knowledge of their specific needs and to what extent the area in question provide or can provide for them.
Before we proceed to harvest animal from an area, we should have an idea of the stock of animals on which the removal may be based on the principle of a sustained-yield and the breeding-stock is not destroyed or endangered. For this; a survey or census of the abundance of the species based upon direct observation, selective trapping, sampling, recording of signs, or even of the abundance of closely associated species, is necessary.
Once the abundance of animals in an area has been established with reasonable accuracy, the recuperative power of the species is to be determined and an idea of the surplus, or yield, that may be safely harvested/gained. Only then we can proceed to harvest the surplus and even then with due precautions which may involve close seasons, limited bags and control of weapons and methods.
Abundance of animals is designated in two ways:
(i) Absolute Abundance:
It is ascertained by numerical counts on definite areas viz. total counts.
(ii) Relative Abundance:
It indicates the abundance in terms of related elements such as the number of animals per trap night; per hour– or per mile. It is also recorded by objectives like rare, common or very common, though this method of recording is less reliable than that based on a fixed-unit.
Absolute-abundance is recorded as “so many animals on an area” whereas Relative-abundance would be “so many animals in a unit of area”.
Frequency of Occurrence:
It is a form of relative-abundance useful in indicating how widely a species is distributed.
For example:
In a fixed-unit count, an individual of a species observed once in 10 hours would be recorded as 0.10 an hour; if once in 10 miles, 0.10 a mile as “Frequency of occurrence” and “Relative- abundance” both.
... In 10 hrs. number observed is 1 individual
... In 1 hr. number observed = 1/10 = 0.10 individual.
It one individual was observed in 10 days, the species would be given a “Frequency of occurrence” of 0.10 and a “Relative-abundance” of 0.10 a day.
... In 10 days number observed is 1 individual
... In 1 day number observed = 1/10 = 0.10 individual.
On the other hand, if 100 individuals were seen on one of the 10 days, “Frequency of occurrence” would be 0.10 but “Relative- abundance” would be 10.00.
... In 10 days number observed are 100 individuals
... In 1 day number observed 100/10 = 10 individuals
(Relative-abundance)
... 100 individuals are seen in 10 days
... 1 individual are seen 10/100 = 0.10 day
(Frequency of occurrence)
Census is essential to ascertain population-status of a species in an area. A census may not be confined merely to sampling but it may include both the main species on which information is desired and the related species. It is desirable to include ecological-factors as well. A census is a definite enumeration and is always recorded in numerical terms.
In wildlife management practice, the main season for carrying out census may be the breeding-season, which generally coincides with the summer, or the cold weather. In America, censuses are generally done before and after the hunting season, when the animals are killed during the season can be estimated; a late winter census is also taken to show the survivals after the winter.
For field studies, controlled or fenced areas may be necessary. When the intention is to prevent wild animals from going into the fenced area, it is known as an exclosure; when the intention is to keep animals from going out of a fenced area, it is known as an inclosure. Islands in a lake serve as inclosures.
The watching of animals and birds from close quarters is possible only from a blind or hide, which is a structure built to conceal the observer. Such blind may be on the ground or in trees. Blinds or hides should be made as larger and as comfortable as possible to permit of a reasonable amount of comfort during watching; but since the animals become suspicious of large blinds, the observation- holes should be as small as possible.
For birds, generally nesting-census (to ascertain the number of birds nesting) and brood-census (to indicate the number of young birds) are taken. In India, census of birds is likely to be more difficult than census of animals because of the difficulty of getting team of knowledgeable ornithologists.
In any method of census, the accuracy depends upon the skilled staffs (enumerators). It is seen that if the staffs are not well-trained, the result or accuracy of even in high quality method becomes unsatisfactory or not up-to-mark. Therefore, it is essential trained and skilled staffs to be engaged in census for getting successful result.
Essay # 3. Types of Wildlife Census:
Census of wildlife is broadly based on two types:
1. Direct Count:
It may be complete or partial (proportionate) such as:
(a) Total Count Method:
In this method all the individuals in a given area are directly enumerated. Such an operation is costly and time-consuming and it is difficult to accomplish it for birds and mammals.
(b) Incomplete Count Method:
Only a part of the population is directly enumerated. It is commonly used in counting fish, a sample of the fish in a fishery being caught, weighed and counted and the result applied to the total weight of the rest of the fish.
2. Indirect Count:
It is always proportionate such as:
(a) Indirect Count Method:
It employs signs such as nests, regurgitated food, pellets, faeces, shed antlers etc. The size of the animal-population is judged from the relative-abundance of these signs.
(b) Marking or Tagging Method:
In this method, a number of animals are caught, marked and released; and afterwards more animals are caught. The ratio between the number of marked and unmarked animals caught gives the estimate of the population.
This method is also useful in tracing the growth-rate, longevity and movements, either local or migratory birds, animals and even fish. Marking may include the use of coloured flexible plastic bands which are pinned or sewn through the skin, usually between the shoulder blades; light metal or plastic rings around the leg; or even paint which is daubed on the bird.
The latter can be applied, where it can come into contact with the feathers of the bird but this may sometimes result in the bird deserting its nest. Also see ahead “Hunting Record Count Method”.
