Read this essay to learn about the methods which are commonly used for estimating the census of wildlife. The methods are: 1. Direct Count or Visual Count 2. Indirect or Index Count Method 3. Miscellaneous Count.
Essay # 1. Direct Count or Visual Count for Estimating Census of Wildlife:
It may be divided into two types:-
(a) Total Count:
In this method, all the individuals of the species of the area/habitat are enumerated. This method gives correct result but it can be done only in limited area having good visibility, because in large area its execution is very difficult. Due to invisibility, there are chances that some animals or part of the area are left out.
It also needs heavy expenditure and large number of labourers. Though; it is supposed that in this method, all the individuals of the species have been counted but there is no any such measurement or proof at this stage that weather all the individuals have been enumerated definitely or some of them have been left out. In real sense, Sample Count Method is more reliable giving more accuracy.
Hence, Total Count Method is not so popular and is used only in the special areas for special animals or birds such as:
i. The area where census is essential on foot.
ii. There is dense forest, undulating or steep hilly areas.
iii. The area is not very large.
This method of census should follow the following criteria before adoption, such as:
i. The area enumeration (census area) should not be very large.
ii. The species to be counted should be of the large size so that they can be easily visible and recognizable.
iii. The number of enumerators should not be very less, otherwise it will take more time and in such case there is chance of duplication in counting the animals; but if the number of enumerators is very large, there is chance of disturbances in the area during enumeration activities.
iv. The staff, engaged in enumeration work, should be well-skilled, trained and knowledgeable.
v. This method is not suitable for the small, shy natured, solitary, secretive and nocturnal animals.
In this method, first of all, the total area is divided into different “Compartments or Blocks” of size not more than 2 kms. These compartments should be numbered. The area with boundary and compartments with number should be mentioned on topo-sheet. If needed, the total area may be divided into different parts due to its enlargement taking the boundary like big river/hill etc.
The census-team should be skilled and trained and provided with the map of the area, watch, binocular, prismatic compass, census-sheet etc. Before starting the census, the key-species to be enumerated should be determined; and according to these species, the route and interval or space (patti) between two parties etc. should be fixed (for big animals, the patti may be wider; whereas for smaller animals it is less, from visibility point of view).
The enumerating team may be single or more, called as “Single Team Census” or “Multi Team Census” or “Line Drive Census”. The Single-team requires less number of staff, whereas the Multi-team requires more numbers. In the team, there must be at least one staff like forest guard who is familiar with the area.
In Single-team; during the census on either sides of the enumerator, assistants will walk in the route on such distances that they may see and hear the enumerator. They will note down on the Field Note Book Proforma regarding the different species seen, with its number and time including their age and sex. The starting and closing time is also to be mentioned in the Proforma.
The Multi-team is like the Single-team census but it is more accurate consuming lesser time because more than one census teams are employed in the census area. In Single-team, only one census team performs the enumeration work in the whole area by moving after one block to another; but in Multi-team more than one census teams are employed performing their duty after one block to another.
For the purpose, a base-line along the length of the census area is made by the help of prismatic compass. This base-line may be treated any forest- road or fire-line, if available. Now, on this base-line, census teams are kept on the equal distances which may be at a distance of 20 m to 100 m depending upon the situation of the forest; such as if the forest is thick, it may be 20 m, if of deciduous condition than 50 m and for open-thin forest it may be taken as 100 m.
This distance also depends upon the key-species. Now, these all teams will start census at the same time towards the census area along the angle of 90° of the baseline (taking reading by the prismatic compass). The reading and record will be taken in the same way as in single-team but it is notable here that the census team of the boarder-line will not count the animals found outside the census area. In one census area, there should be minimally 10 and maximally 20 teams.
The teams should be in well contact so that it may communicate its adjacent team and the space (distance) should be maintained throughout. The length of the track of the each party may vary because the starting time of all the teams being the same, the finishing/closing time will vary but the walking speed should be more or less the same of all the teams; otherwise the same animals will be counted by the other team also and, hence, will be enumerated twice and so on. Summarizing all the census sheets of the different teams, the total number of the population (species wise) for the whole area is calculated.
Total Count Method can be divided into two types:
(i) Spatial Count:
In this method, the counting is done at a particular time for the entire area.
It is performed by anyone by the following methods:
(1) Drive Method or Beat Method:
It is one of the most common methods of census. Men walk across the area in a line and count the birds and animals that cut back through the line to one side and enumerators are stationed at vantage (fixed) point to count birds which fly out of the census area. The main count consists of the birds or animals which cross a cleared line on which observers are posted.
In this method, the animals and birds are driven from their hidden places in the area of census. There are some persons in this drive-party and some others will sit on the trees in the different places of the compartment. Due to driving, the animals come in front of them and move in forward direction while the birds fly off.
The flying birds are recorded and the passing animals are recorded by the enumerators sitting on the trees at a fixed point of the compartment like crossing the broader- line or any other clear patty of the compartment. To avoid double counting, it is to be noted that the animals will be recorded by the enumerators passing only one side, left or right.
The work is done in each block and is finished in a single day for the whole area to avoid possibility of mixing of counted and uncounted animals. Precautions are also taken for avoiding the double counting of the animals from one block to another and so the enumerators are also kept at the borders of the area which is to be censured (the other area where census has not been done yet) so that the counted animals may not move towards the uncensored area. This method has been applied in U.S.A. in case of deer and birds successfully.
(2) Visual Method:
This method is applied in the area which is totally open or where the total animals of the area come collectively at an open place at a particular time. In such cases, the animals are counted by approaching near to them or by the help of binocular.
For instance; at Kanha National Park in a pasture area, the cheetals of the entire area get together in groups in the month of July and swamp deer in the month of March/April, and, thus, they may be counted for few days repeatedly and then final result may be obtained.
(3) Aerial or Photographic Method:
If the area is open and the animals are found in groups, they may be counted by air flying in small aeroplane. If the species is of small size such as birds etc. and their number is large, their photographs may be taken by the aeroplane and its number may be enumerated in the office by the help of their snaps.
(ii) Temporal Count:
This is the method of census of a fixed area at a fixed time. In this method, the whole area is supposed to be limited at a fixed point or area where the animals are counted crossing in a fixed time or period. Such census is adapted for the migratory animals that cross from one habitat to another.
For counting such species; they are enumerated, in the migratory- season, at a clear migratory-route like National Highway or such other path. But to observe the migratory-route very well and count the total animals is particularly not possible; and, hence, this method is not so much satisfactory or reliable as the spatial- method.
(b) Sample Count Method or Partial Count Method:
Sample count is that method of enumeration in which the representative samples are chosen in the area. In the sample, the animals are counted by “total count method” and, on this basis; the total number of the animals (population) in the whole area is calculated statistically (by multiplying the whole area to the density of the population of the sample area).
In total count method, all the individuals of the population in an area are counted; but it is generally not possible to count all the individuals on a large area and, therefore, in forestry “partial-counts” (equivalent to the partial enumerations) are employed. For the purpose, “sample-area method” is adopted which gives reasonable accuracy. Like other kinds of sampling, care should be taken in the selection of the sample or census-plot so that it should be true representative of the area.
The selected sample-area should include all types of habitats in representative quantities of the region, and when this is not possible, separate sample areas for each type of habitat are advisable. Randomising sample-plots (random-sampling) is also necessary. The most common sample-plot is the “quadrat” whose size and shape may vary.
The extended quadrat or linear-quadrat has the advantage of covering many different types of covers and aspects. Another sampling device is the “transect” which is merely a line running with a compass in such a manner as to include representative areas.
A transect is convenient for quick sampling in large area, remote regions and in rough country. But the sample- count method is difficult also because in this method abstraction is to be given to the statistical assumptions and, hence, requires knowledge of statistics.
From census point of view, some terms are defined as follows:
A small group or fraction taken from the “Aggregate of population” to whom we want information, is called “Sample” of that population, and the methodology of forming such sample, is called “Sampling”. Hence, in sample-count method, the counting is done only in sample areas and this result is extrapolated for the whole area.
For the purpose, the density of the population in sample plots is calculated, and then total population for the whole area is obtained by multiplying into total area; or may also be obtained by summing up the numbers of the animals of all the sample plots in the total area.
The measurement of the intensity of sampling is called Sampling-Fractions. Hence, it is the ratio of the area of the samples where census was carried out and the total area to be censured (from which sample-plots were chosen).
Sampling Fraction = Area of sample where census was carried out/Total area
Sampling Percentage = Sampling Fraction × 100
In sample-count method, the total forest or area, where census is to be carried out, is called “Universe”. This universe or total area is divided into small units which are called as “Sampling units”. Now, within these sampling-units, some of them are selected/chosen by any one of the sampling-methods as the representative units, which is collectively called as “sample”.
For example; suppose the total area is 10,000 ha where census of a particular species is to be carried out, this total area is divided into 1000 units, each unit containing 10 ha area which is called as Sample- unit or Sample-plot. Now, within these 1000 units, through statistical sampling method, 50 units are chosen as the representative and collectively known as “Sample”. Hence, the area of sample will be 500 ha. containing 50 units or sample-units bearing 10 ha area each.
In these sample-units by total-count method, the number of desired species is enumerated. Now; from this counted number in the sample, the approximate total number of the desired species in the total area (here 10,000 ha area) is calculated statistically. The “Confidence-limit” of the result is also calculated statistically.
In the above example Sampling- Percentage will be:
Thus, we see that this method is comparatively more reliable and consuming lesser time but needs statistical knowledge.
Sampling-methods or formation of sample are as follows:-
(i) Random Sampling:
It is that type of sampling in which each and every individual of a population has free opportunity and chance to be selected (randomly) in the sample. Hence, in this method of sampling, the sample-units/plots for the purpose of sample are chosen randomly. For example, if the total area is 10,000 ha and sample unit area is 1 ha; then the total number of sample-units will be 10,000 which are numbered.
Now 5% sample-units are to be selected means 500 sample-units are to be chosen as representatives. For the purpose, 500 sample-units will be chosen through lottery or picking up randomly any number out of 10,000 sample-units. Thus; in this method, each sample-unit has equal opportunity and chance to be selected/chosen as the sample-unit for the sample.
But this method is not suitable for census of wild animals because of the following reasons:
a. Wild animals are not randomly distributed in nature.
b. In the census area, each and every block or compartment or unit is not identical due to uneven distribution of so many factors such as waterholes, food, shelter or cover, roads, mosaic of habitats, microclimates, edge- effect, juxtaposition etc. Hence, the animals are not evenly distributed throughout the area and subsequently vary in different sample-units. Therefore, the census adopted by random-sampling method will not be accurate and up to mark.
(ii) Probability Sampling:
This method may be applied in case where the possibility of inclusion or non-inclusion of each individual in the sample is known. The sampling is done on this very basis. Hence, it is clear that this method is not suitable in wildlife census. It is non-random sampling.
(iii) Systematic Sampling:
It is a kind of non-random sampling. In this method, the sample-units are selected on the preplanned pattern and generally the models of the units are based on the regular interval. Sample-units may be in the form of part of the land area or as transect (patti) of certain fixed width.
For example, if the area is divided into 20 m wide transects (patties) and among these each 10th transect is to be enumerated; it is systematic sampling. The aerial census by aeroplane in the large areas is also a kind of systematic-sampling.
But in this method; there is chance that certain sample-units may be either very rich in the population due to riparian zone etc., or may be very poor due to dryness etc. In such cases, the calculation of the population will not be up to mark. Hence, this method is not suitable for wildlife census.
(iv) Two-Stage Sampling:
In this method, some sample-units from the whole area are chosen; and then again among them, some sample-units are chosen; and then again among them, some sample-units are chosen. Since in this method; sample-units are selected twice, it is called as two-stage sampling method. But this method is also not suitable in wildlife census.
(v) Stratified Sampling:
It is that method of sampling in which the whole area, first of all, is divided into different dissimilar strata and then sample-units are chosen randomly in those different strata as per the proportion of each stratum-area. Hence, it is called as stratified-sampling or stratified- random sampling.
Since; in this method, the area is divided into different strata as per the status of the animal and then sample-units are selected from each type of stratum according to the area; the result of census for the whole area will be more precise and accurate.
From wildlife census point of view, this is the best method among all the sampling-methods because in nature the dispersion/distribution of wild animals is different due to different factors and subsequently their number significantly varies from place to place or area to area. Hence, among all the sampling- methods, “Stratified Sampling Method” is the best for wildlife census.
In this method, following methodologies are adapted:
1. The whole area is divided into different strata on the basis of diversity.
2. From each stratum, one sample is selected randomly.
The area of the sample should be of optimum size to get more accuracy in the result. The small size sample will also increase the number of sample-units which will help in getting the precise and accurate result. The sample- size should be minimally 0.1 (10% sampling- percentage) and maximally 0.25 (25% sampling-percentage) of the area.
3. Population Mean is estimated statistically.
Stratified Counting or Sample Count Method is of following two types:
(a) Block Count or Stratified Block Count Method:
In this method, following steps are followed:
(i) First of all, the whole area is divided into different small parts on the basis of the nature of the habitat and the density of the animal species. A compartment may be treated as a division (part) but if the density of the animal differs within it, the compartment should be divided into parts as per the necessity. The map of the area along with the parts (divisions) is traced out.
(ii) Now, each part is demarcated as per its stratum. The allotment of the stratum is done on the basis of forest density, dominating species etc. For example, dense forest, open forest, pasture area etc. may be different types of strata.
(iii) Now, the total area of each stratum is obtained by adding the areas of the parts/compartments/divisions of the each stratum.
(iv) Afterwards; from each stratum, some representative compartments/parts/divisions are selected randomly as sample-plots/sample-units consisting 10% area (or, as per preplanned choice) of the total stratum area.
(v) Now, census is carried out in these sample units by direct-count method.
(vi) Now, the density in each sample-plot for each species is obtained (by dividing the obtained number of the species in the sample-plot by the area of the plot). In this way, the density in each plot for each type of species is obtained and then the average density of each species in each stratum is calculated.
Now for each stratum, the population (number) of each species is obtained by multiplying into the total area of the stratum with the average density of the species and then 95% confidence-limit is found out.
(vii) The whole data is noted down on the chart (Proforma) for different types of species.
Suppose there are three strata in the census area like A, B and C on the basis of dense forest, open forest and pasture area respectively.
If Total area of census = 600 km2
Area of Stratum A = 200 km2
Area of Stratum B = 200 km2
Area of Stratum C = 200 km2
Sample Size = 10%
... Area of Sample in each stratum = 20km2
... Area of total samples in all three strata = 60 km2
If Area of each sample plot in each stratum = 2km2
... Number of Sample-plots in each stratum = 10
... Total number of Sample-plots in all three strata = 30
Hence, ten sample-plots will be chosen randomly from each stratum and census will be carried out in these sample-plots by direct- count method for different types of species and are noted down in the chart.
Suppose, numbers of cheetal is to be calculated; For the purpose, the Mean Density from the chart in each stratum (from 10 sample-plots in each stratum in this example) is found out like 10.04, 6.93 and 4.33 in A, B and C stratum and confidence-limit as ± 0.84, ± 0.66 and ± 0.78 respectively (Table-1).
Therefore, the population of cheetal will be as follows:
Stratum A → (10.04 ± 0.84) × 200 = 2008 ± 168
Stratum B → (6.93 ± 0.66) × 200 = 1386 ± 132
Stratum C → (4.33 ± 0.78) × 200 = 866 ± 156
Total = 4260 ± 456
... Total population of cheetal in total area = 4716 or 3804
It means the population of cheetal in that area as 95% situation will be either 4716 or 3804. In the example, sample-size is 10% and if it is taken 20% then precision and accuracy will be more because in this case the number of sample-plots will be more and subsequently confidence-limit will be less.
The population may also be calculated statistically which will be more accurate and reliable in the following way:
The value of “t” depends upon Degree of Freedom i.e. (n-1). Its value may be noted from the chart. When Degree of Freedom (n-1) < 12 but > 1 then the value of “t” is between 2.20 & 4.30 and when (n-1)> 12 but < 50 then the value of “t” is between 2.20 & 2.10. Hence, the value of “t” may be taken as 2.10 for more than 10 observations. Here, the value of “t” has been put as 3.0 for convenience as in the example (n-1) is equal to 9 and the value will be the same in all the three strata because in all (n-1) = 9.
(b) Transect Count or Stratified Transect Count Method:
It may be divided into following two methods:
(i) Road Count Method:
This is also a kind of sampling method. This method is generally used to find out the trend of growth in population number because this method is very easy and convenient to access the trend of abundance or compare the number of species counted in different times in the same area in the same ecological situation. If vehicle is used in this method, it is called as “Transport-based-Transect Method”.
In this method, transect-sample is chosen. For the purpose, treating any compartment or block as sample, the area of patties (transect) on either sides of any forest road (inside the census area) is chosen as transect-sample.
Such selection should be in such a way that:
1. The chosen forest roads represent truly all the representative areas.
2. The length of the forest road is in the ratio of the representative area.
3. The ecological condition of the edges of forest-road is alike the area through which it is passing.
4. The visibility of all the available animals is similar in the transect.
5. The visibility of all the animals up to normal distance is similar in the transect.
Population of the species in the census area is calculated by multiplying the density into the total area.
To fulfill the above objectives; in the whole census area, so many forest roads like net should be constructed passing from all types of habitats and strata. Such road should not be chosen where there is frequent plying of vehicles because dust settled on the flora on either sides of such road minimizes the density of the animal-population while it is more in inner side of the road.
Besides this; due to edge-effect and cuttings for fire-lines also minimizes population-density and, hence, different types of forest roads as samples should be chosen for different types of strata. The time of the census should also be considered at which the key-species are maximally active, for example, it is appropriate for deer and antelopes at 6 to 9 morning and 5 to 7 evening.
The speed of the vehicle should not be more than 15-20 km/hr. Regarding visibility; it is difficult and not uniform in dense forest in comparison to the open and grassland. There is also not uniform visibility in nature inside the forest even after taking different widths of transects in different types of forests. Hence, these possibilities should be viewed and thought at the time of fixing transect-width.
It is of two types:
(a) Fixed Width Transect:
When the width of the transect (patty) on either sides of the road has already been fixed, it is called as Fixed Width Transect. Since in forest; the sighting from one place to another changes due to so many reasons, this method of transect width is not suitable.
(b) Open Width Transects:
In this method, the animals are counted on both sides of the forest road (transect) up to the Distance of Visibility (Sighting Distance) and its Angular Distance (Radial Distance/Angular Sighting Distance) from the enumerator is also noted down. This angular- distance of the animal from the enumerator is converted into Perpendicular Distance.
On the basis of mean of at least such 50 observations, Optimum Distance for each species is found out (after which sighting-distance starts decreasing). This Optimum Distance of that species will be Mean Perpendicular Sighting Distance.
At the time of counting, the animals will be counted only within this distance (Mean Perpendicular Sighting Distance) in the transect and others beyond this distance will be left out. The calculation of the population of a particular species will be on the basis of its number found within this perpendicular-distance. Hence, this method is called Open Width Transect/Indefinite Width Transect and is suitable for the wildlife census in the forest.
Hence, on the above basis, the number of species is counted in each sample (transect) and then Mean Density is calculated; and by multiplying this into the total area of the census, the total population of a particular species is obtained. Compass may be used for angular reading and binocular may be used to observe the animals.
Where N = Number of particular species seen in transect.
L = Length of transect in km.
2 = Multiplier for either sides widths of the transect.
r = Mean Angular Sighting Distance in km.
Angular-distance and Perpendicular-distance depend upon the topography of the area but maximum animals are seen at the angle of 30° or 60° and the average of both the angles is about 1.6.
... r = 1.6 × (where X = Mean Perpendicular Distance)
After finding Mean-density, the total population of a particular species is obtained by multiplying the density into the total census area.
(ii) King Method & King Greed Method:
This is also a type of Sampling method under direct count method in which population is estimated supposing the transect as the basis. This method is simple, accurate as well as changeable in accordance with the species, land topography and local necessities. This method is very useful in case where there is no road and census is to be done on foot.
In this method, number of animal is calculated per unit area of the total transect samples on the basis of the animals observed at Angular Sighting Distance calculating “r” in each transect-sample as per the procedures and formula described in Road Count Method. The estimation of total population is then also calculated as per the formula described in the Road Count Method.
Radial-distance is noted by the help of compass reading. Binocular may also be used to observe the animals. The length of one transect should not be more than 10 kms, If the enumerator is passing on foot then the distance is measured by his pace (generally the average distance of one pace is equal to 0.8 m).
In Greed Method, the whole area is divided by parallel greed- lines at fixed intervals (usually at 20 or 40 m intervals). Each greed is treated as a sample-plot. The enumerators count the animals moving along these lines by the help of compass or the pointed trees, already marked for the purpose along the lines.
Then total number of the animal is calculated. This method is more useful in counting the birds but it is not suitable in the area where animals are found rarely, the preferred-foods of the animals are at only certain places and there are elevational-variations in the vegetation.
2. Indirect or Index Count Method for Estimating Census of Wildlife:
It has been divided into following types:
(a) Pug Mark Count/Track and Trails Method/Track Method:
As a natural phenomenon, the pug mark of each individual of a species is different from that of the other individuals in certain respect. It means each and every individual of a species can be recognized on the basis of its pug-mark and, hence, they can be counted in a certain area.
The pug-marks of some animals like tiger, lion, leopard etc. are so specific and characteristic that they can be counted accurately on the basis of their pug-marks. Not only this, but their pug-marks also have certain morphological differences in respect of male, female as well as cubs; and, therefore, they are enumerated as such.
So, on the basis of morphological- disfiguration of the foot-print, individuals can be counted. This, reading of signs or tracks of animals is essential in wildlife management because correct reading of signs is necessary for correct interpretation of evidence. In general, it is common that animal leaves sign or its passing like foot-prints in sand, mud or snow; the dropping of dung or faeces; the regurgitation or indigested food by birds in the form of pellets; the trails left by large animals in grass or jungle; blood-trails left by wounded animals; the signs of nibbling of grass and leaves; the rubbing-off of the bark of saplings by the antlers of deer to remove the velvet etc.
For the first time, Nicolson applied this method in 1934 at Palamau (Jharkhand State); afterwards Dharm Kumar Singh and Sankhala in 1967 did certain modifications in this method, but Sarofraj Choudhary in 1971 valuably modified it and invented a simple instrument like “Tiger- tracer”. H.S. Pawar (1980) studied this method deeply and made it popularized. Thus, this method has been invented and progressed in India itself.
The pug-marks or foot-prints of many larger animals are enumerated by understanding their characteristics such as:
(i) The foot-print of a male carnivore like lion or tiger can be distinguished from that of the female by the more rounded impressions of the individual pads of the male and the more pear- shaped or pointed impressions of the female.
In case of tiger, generally the left hind foot print is traced (if it is not available then right hind foot-print) because fore-feet are identical (square) in both male and female as they are used for attacking the prey and, hence, cannot be differentiated. On contrast, the hind foot-print in both the sexes are of different kinds; viz. in male, the right angled quadrilateral made by the lines traced outwardly the foot-print is found square-shape, while in female it is rectangular.
When the tiger is in normal movement, the hind feet are placed on the fore feet itself. Since the foot-print of fore feet is comparatively larger and, hence, the tracing (on tracing plate) of hind foot print inside the fore foot print should be taken carefully.
But when the tiger is in motion or in running condition, the hind feet are placed somewhat ahead from the fore feet and in this situation the foot-prints of hind and fore feet are separate; and in such condition the tracing should be after careful observation. The tracing should be repeated five times for accuracy.
The length of the stride (from the apex of fore left middle finger to the apex of hind left middle finger) should also be noted down repeating five times. Though tiger moves solitarily, but at the time of courtship there are many foot-prints together with tigress and cubs; and in this condition, the tracing of foot-prints should be taken separately (tiger, tigress and cubs) observing carefully. In addition, the Plaster Cast by Plaster of Paris should also be prepared and kept for more information and further investigations.
Before starting, the area should be divided into different beats/units as per convenience. The place, where foot-prints are to be traced, should be cleared one day before in evening/night to avoid previous foot-prints.
Such spots should be chosen where there are chances of clear tracks (signs) of foot-prints like muddy portion near waterholes, sandy soil, ant-hills, moist places etc. If required, sprinkling of dust or sand across the track or smoothening by sand on the path may be done so that the animal will be forced to leave sign of foot-prints upon them.
The tracing of foot-print on tracing-paper by the help of tracing-plate should be taken parallel to the foot-print to avoid Parallax-error. Since the fifth finger is elevated from the ground, so the prints of only four fingers remain on the ground.
(ii) The foot-prints of male, female and cub of the lion can be differenced by the criteria like:
(a) If the difference between length and width of foot-print is less than 1” then it is male; and if more than 1” then it is female.
(b) If the length of the foot-print is more than 5” then it is male; or if length is 4 ½’’ – 5″ then it is female.
(c) If the measurement of pad is more than 3 ½ ” then it is male; and if it is less than 3 ½ ” and approximately 3 ¼ ” then it is of female.
(iii) The pug-mark of a tiger cub can be distinguished from that of a panther by the proportionately larger size of the individual toe-impressions of the former.
Panther is also found in area of tiger and its foot-print is a like tiger cub. But it is to be remembered that the foot-print of an adult panther is not larger than the foot-print of six months old tiger cub, who always remains with its mother up to this age. Hence, if such small foot-prints are not available along with the foot-prints of tigress; then such small foot-prints belong to panther.
(iv) The tract of a hyaena can be differentiated from that of a panther by the larger impressions of the toe-pads and the imprints of the toe-nails of the hyaena.
(v) The difference between the foot-prints of a pig and a deer can be recognized from the depressions left by the two rudimentary toes at the back of the cleft-hoof in case of the pig.
(vi) Otter’s track will show the webbing between the four toes.
(vii) Mangoose’s track can be distinguished from that of a civet-cat by the claw-impressions of the former.
(viii) Jungle-fowl’s track is similar to that of a pea-fowl but smaller with the hind toe at a backward angle.
(ix) Non-poisonous snake has speed to capture its prey and so its track is comparatively straight than that of poisonous snake.
(x) The passing of a porcupine can generally be recognized by the fine lines made by the dropping quills of the animal as it drags them along the ground.
(xi) The number of animals in a herd of spotted-deer (cheetal) can be roughly estimated by counting the number of foot-prints between two parallel lines drawn 30″ apart at right angle to the direction of the foot-prints and dividing the number by two (for the distance between the hind and front hooves of a cheetal generally having average-size of 30″).
(xii) The impression of the rear foot of a tusker elephant is pear-shaped while that of a makhna (tuskless) male is more rounded.
To distinguish the various sounds of the animals is also for their particular significance and importance; for example:
1. The grunting cough sound denotes a charging tiger.
2. The cat like yowl is of a dying-tiger.
3. The high pitched musical sound notices a tiger calling to its mate.
4. The loud hissing sound is the symbol of an angry or frightened tiger.
5. The high sambar like “keek” is for a hunting tiger.
6. In elephant (on the basis of field experience), it is found that:
(i) If pinna moving forward and backward, trunk and tail in normal position; the elephant is in normal mood.
(ii) If pinna static, tail twisted and moving; trunk twisted and moving up and down the elephant is in frightened mood.
(b) Dung/Pellet Count:
Dung count method is actually useful to know the availability, non-availability or abundance of wild animals in a particular habitat especially mammalian species. Counts of pellets, droppings and other faecal materials for their enumeration have been made for a number of species such as deer and other large ungulates, rabbits, small mammals and in certain cases of birds. But the most widespread pellet-count method is for deer.
In U.S.A., this method is applied since many years in counting deer and rabbit etc. Though in tropical countries, like India, this method is not very useful because the pellets are destroyed soon by dung-beetles, decomposers or rains; however, in winter season this method gives some valuable data in comparing and counting the population.
In this method, for counting the number of a particular species, the density of the particular species is found out on the basis of discharged pellet-groups and then this density is multiplied by the total area to estimate the total population. For the purpose; first of all, the number of pellet-groups defecated in one day (24 hours) by one individual of the particular species is found out which is treated as the “Standard-rate of Defaecation” or, “Standard Defaecation-rate”.
Afterwards; in an unit area, the number of pellet-groups discharged by the individuals of the particular species in a particular time (generally in one month viz. 30 days) is found out and then dividing this number by Standard Defaecation-rate, the density of the population is calculated and subsequently total population (by multiplying density with the total area) is estimated.
Standard-error (S.E.) and Confidence-limit may also be calculated from the data to get more accuracy in the result as stated in Table-1. In this process, Stratified Sampling Method is applied; and generally in each stratum 10 transect-lines are made a parting 200 metres and on each line 5 sample-plots (each having 30 m x 2 m size) at 50 m intervals are chosen.
In each transect (in 5 sample-plots), number of pellet-groups of the species is noted down and then average value for all 10 transects (50 sample-plots) dividing total number by 10 is calculated which will be the average number of pellet-groups per transect (in 30m x 2m x 5 = 300 sq. m. area) of that stratum. Further, density and total number of animal (species) in total area is estimated. For more accuracy, Standard Error (S.E.) and Confidence Limit may also be put in the calculation.
There are certain assumptions of this method such as:
(i) The pellet-groups of different species are different, for example, there are differences in the structures of pellet-groups of cheetal, sambar, black buck, barking deer, chausingha etc. But the pellets of adult cheetal and young sambar, barking deer and chausingha are almost alike and needs expertisation to distinguish between them.
Pellet-groups may be counted separately. But some species like nilgai defaecates at the same spot for several days and, in such cases, the pellets may be counted for different days on the basis of new and old considering its colour and so on.
There are some demerits also of this method like:-
1. The pellet-groups are destroyed in some seasons specially in rain etc.
2. Pellet-groups are destroyed by insect attack like dung-beetles, decomposers etc.
3. The nature of food and age of the animal affects the number of pellet-groups per day per animal.
If in 50 sample-plots, each having 0.006 ha (30 mt x 2 mt = 60 mt2), the number of pellet-groups of deer has been found 135 in 30 days, then the number of deer in each sq.km. (per sq.km.) is to find out (supposing one deer in one day makes 15 pellet-groups).
Number of pellet-groups of 1 deer in 1 day = 15 (Defaecation rate)
Total area of 50 sample-plots = 0.006 x 50 ha
... Number of animals per ha = Number of pallet – groups made in 1 ha in definite period/Number of pallet – group made by 1 animal in definite period.
= 0.3 ha
Number of pellet-groups in 30 days in =135
0.3 ha area of 50 sample-plots
... Number of pellet-groups per ha = 450
1 deer in 1 day makes 15 pellet-groups
... 1 deer in 30 days makes 450 pellet-groups
... Number of deer in 1 ha = 450/450 = 1
... Number of deer per sq.km. = 1 x 100 = 100
In a particular stratum of the census area, 10 transects (transect-lines) have been made keeping 5 sample-plots on each line of 30 m x 2m size. If the total number of pellet-groups of cheetal in all 10 transects is 78 in the period of one month (30 days) and the defaecation-rate of cheetal in 24 hours is 15; then the density of cheetal in that stratum will be as follows:
Total number of pellet-groups in 30 days = 78
... Average number of pellet-groups in 30 days = 78/10 = 7.8
Area of sample-plots (5) of one transect = 30 × 2 × 5 sq.m = 300 sq.m.
... Number of pellet-groups in 1 sq.m in 30 days = 7.8/300
... Number of pellet-groups in 1 sq.km in 30 days = 7.8 × 1000 × 1000/300 = 26000.
or, [Average no. of pellet-groups in 30 days = 78/50 = 1.56 in 1 sample-plot (30 x 2 sq.m.)]
... Number of pellet-groups in 1 sq.m. = 1.56/60 in 30 days
... Number of pellet-groups in 1 sq.km in 30 days = 1.56 × 1000 × 1000/60 = 26000
... Number of pellet-groups per sq.km. in 1 day = 26000/30
In 1 day (24 hours) 1 Cheetal discharges 15 pellet-groups (dafaecation-rate)
... Number of cheetal per sq.km. = 26000/30 × 15 = 57.77
(Density of cheetal in the particular stratum)
... Density of cheetal per sq.km. = 57.77
Likewise, the density of other strata may be found out and average density may be calculated and then finally by multiplying it into the total census area; the total number of the species may be estimated. For further accuracy of the result, Standard Error (S.E.) and Confidence Limit may also be computed in the calculation.
(c) Hunting Record Count Method:
This method is actually applicable in the countries where there is no ban on hunting as well as there is control and record on hunting. Since, in India, there is ban on hunting of wild animals, this method is not applicable.
At first, Lincoln (1930) applied this method for water-birds and is supposed an important achievement in the field of census for estimating population of the species specially for birds. That’s why, it is also called as “Lincoln Index Census Method” or “Marking or Tagging Method”.
It is based on marking of birds or animals and later on counting of marked individuals caught or killed in hunting.
It is expressed by the formula:
Lincoln noted that the number of marked or banned birds killed annually was in certain percentage of the birds marked or banned annually over a period of years. Hence, if 10% of the marked animals are killed/caught, the total population should be approximately 10 times than the total number of animals killed/caught by the hunters.
This method is subject to many possibilities of error, one of which is due to the difficulty of proper mixing or distributing the marked animals.
Hence, there are certain assumptions to use this formula such as:
i. That the mortality is the same for both marked and unmarked animals.
ii. That the marked individuals do not-lose their marks.
iii. That the marked individuals are caught/killed at the same rate as the unmarked.
iv. That all marks are recognized and returned to the investigators.
v. That the requirement is insignificant during the operation.
(d) Call Index Count/Trend Count/Auditory Count:
This method does not indicate the density of the animal but denotes tendency of the density/abundance of the wild species in a particular area. The sound of the wild animal related to its courtship, danger etc. indicates its presence in habitat area but the absence of the sound does not mean its actual absence in that area because the sound/ call of a particular species varies according to the time and the season.
However; in this method, sound of the animal is used as a instrumentation/indicator and becomes the basis of its count or abundance, and in real sense this method is useful to estimate the abundance of a particular animal in particular habitat.
Since in mating-season, the male bird calls its opposite sex which varies and minimises as per the time and season as well as females and juvenile birds generally do not give such calls; hence, there counting is not possible. Even then, this method may be useful for special-population-estimation as well as in comparative studies and not for temporal basis.
Generally, the population-estimation through this method is done for the birds like quail, partridge, pheasants, jungle fowl, saras, parrot, cuckoo, hornbill etc. This method is not useful for mammals.
The method of counting is adopted as in transect method of Stratified-sampling and the call of the bird is audited and noted on the base-line by the observer team and then perpendicular-distance is found out and ultimately density is calculated by the formula.
3. Miscellaneous Count for Estimating Census of Wildlife:
There are some methods of counting which cannot be included in direct or indirect count method and, hence, called as Miscellaneous count method in which some important methods are as follows:
(a) Waterhole Count:
This method is mixture of indirect (index) and direct methods because here waterholes are used as an index while animals are counted individually directly. Actually, this method is used to find out abundance or trend of abundance but also used for population-estimation.
This is the most useful in summer season because in this season there is minimum number of waterholes which facilitate to count the individuals in lesser time.
We know that the animal visits the waterhole for drinking purpose at least once daily. In this method, the privilege is taken of this habit of the animal. Hence, if the frequency of the water-taking is known for the key species; the number of population of that very species may be estimated by dividing the total number of individuals counted at different waterholes by the frequency.
For the purpose, all waterholes of the total area in summer season are surveyed. The hide is formed at every waterhole and the enumerator- team approaches there in full-moon night in the evening before sunset. Every team counts and notes down the number of the individuals from 6.00 P.M. to 6.00 A.M., and if possible, its sex and age are also mentioned. Finally, the number of individuals (total population) of the species may be found out by complying the data of all the waterholes.
There are certain assumptions in this method which are mainly as follows:
1. That each individual comes certainly at the waterhole for drinking purpose within the counting period.
2. That there is direct relation between the total population of the species and the individuals are seen at certain intervals at each waterhole.
3. That at each waterhole, the enumerator-team is present and they are able to count them.
4. That the frequency of water-taking is known for the key-species (means that how many times, an individual of a species visits the waterhole within 24 hours).
(b) Ratio-Based Count:
In this method, the known number of individuals are mixed in unknown number of species-population (the population which is to be counted); and then by sampling method, the number of known and unknown individuals are counted in sample.
There should be precaution that the animals which are to be mixed in unknown population should be such that the sighting is at par with the unknown population.
The total population of the key-species is estimated by the formula as follows:
(i) There is one method in which the domestic animals are mixed in the unknown population of the key-species and then the numbers of domestic and wild individuals are counted in at least 10% of the total census area as sample.
The total population may be enumerated by the formula:
(ii) There is another method in which some individuals of the key- species itself are marked and left for mixing; and then in sample, both the marked and unmarked are counted.
The total population is found out by the formula:
This method is the most suitable for small size mammals.
For counting the big size animals by this method, the marking in the individuals within that very species is searched out and the total population is counted. In this way, the method is called as “Sighting and Re-sighting Method”.
(c) Kill-Evidence Method:
The killing method of the predator may indicate the trend of its presence and abundance.
(i) The tiger kills its prey with its teeth on the neck (it is generally believed that tiger kills by giving a smashing blow on the neck, it is incorrect; tiger kills with its teeth).
(ii) The tiger starts its feeding from the haunches and will not burst the paunch or stomach, and often moves its kill to some distance away.
(iii) The leopard kills by biting through the throat.
(iv) The leopard, which is called a dirty feeder, starts its meal at the anus of the dead animal.
The way of concealing the kills by the different predators is also important such as:
a. The tiger sometimes hides its kill with leaves.
b. The leopard may take the kill up to the forks of the tree.
In Indian conditions, any exhaustive and expensive census method is not likely to be acceptable, because here the management of wildlife as a commercial-crop is subordinated to the task of conserving the remnants and controlling its injurious elements.
However, idea and trend of census of important species are as follows:
(i) The larger carnivorous animals such as lion, tiger and leopard can be counted by the track-method which can be combined with the method of baiting and counting. Lions specially can be counted over kills or baits as they have the habit of congregating at kills.
(ii) Animals like cheetal, sambar and barking deer which inhabit light to heavy tree forest can be counted by the drive-method. For sambar and swamp deer, privilege may also be taken of their habit of roaring in the rutting or mating season. They are gregarious and can be counted easily in grassy fields or blanks in morning or evening. The sexes can be estimated through the habit of the males moving in groups.
(iii) Bears can be counted at ant-hills and also by track-method and by direct-count method viz. observing them when they emerge from their dens in the evening or return to them in the morning.
(iv) For animals of the drier and open type of forests such as Indian gazelle (chinkara), Indian antelope (blackbuck), nilgai etc.; aerial- census combined with ground-counts is useful. Certain species like chinkara and four-horned antelope (chausingha), which are of a secondary nature, may be counted by observing their scrapes or beds.
(v) For hog beer, living in high grass, the drive-count method utilizing elephant is useful.
(vi) For mouse deer, which haunts dense jungle or rocky hill slopes, short drives and silent beats are useful.
(vii) Wild pigs move in families and can be counted as they are gently driven across a cleared line.
(viii) For rhinoceros, elephant, bison and wild buffalo, which inhabit heavy jungle, the direct-count combined with track-method give good result. Rhinoceros congregate near cultivation at certain times of the year and, hence, can be counted on full moon night or from the elephant riding during the day in the area adjoining crops.
In the hot weather when the grass has been burnt, aerial- survey combined with ground-counting may be useful. Elephants move in certain regular beats according to the availability of fodder and in the dry season are never far from water, may be counted directly. Bison feed regularly in certain area and can be counted easily under such circumstances.
Now a days in developed countries, “individual marking” of the animal is in progress in order to get the most meaningful data, breeding- management, maintenance of sufficient genetic-diversity, behavioural- management, national and international cooperative breeding programmes, scientific management, healthcare etc.
But unfortunately, in our country, such methods of individual identification have not been adopted due to being very expensive and lack of proper skillness. There are several methods of individuals-marking such as natural marking, permanent deformities, cut marking, tattooing, branding, dyes and paints, computer chips/transponders (It is the recent electronic marking which can be injected into the animal with a syringe.
It is easy to insert, undetectable, useful to identify even stolen animals and life-long. It lies dormant until activated by a transmitter-reading device or scanner. However, it is very expensive and the animal cannot be identified from a distance which may be overcome in future by the advancement in electronic field.)
Since all marking methods have their positive and negative points, the basic rule is to select the method that works in the best way and easier to use for the species. By identifying the animal individually, we can study the animal in detail and manage them scientifically by applying proper management techniques.