All of you are definitely aware about human census, today I am discussion about Wildlife census and why it is done. The key goal of the any census is to determine the density of the species' population and to collect basic data for management aspect. Like humans, the population of wildlife animals and birds does not always remain constant. Its population grows/dwindles in different places, implying that the population of the same species fluctuates from place to place and from nation to nation. It also varies from year to year and even from season to season. Due to this, a single census is insufficiently informative from a management standpoint, and censuses should be conducted on a regular and periodic basis, followed by analysis, so that the number of species-populations may be reliably determined in various seasons and situations.

Though census is the most important phase in the management and conservation of wild animals, it is a time-consuming and difficult task because the animal population is dispersed throughout the area/habitat. Census delivers an estimate of the population of a specific species in a specific environment at a specific period. It also gives idea on whether or not any species is on the verge of extinction. We can determine the population status of a species, such as whether it is surplus, rare, endangered, or on the verge of extinction which is very important from conservation status. It also provides a notion of species population in various seasons, conditions, and years, which is important from a management standpoint. It also gives an estimate of the habitat's carrying capacity for the species in question.

For birds, Nesting-census (to determine the number of birds nesting) and brood-census (to determine the number of young birds) are generally taken. Because it is difficult to find a team of knowledgeable ornithologists, bird censuses are likely to be more difficult than animal censuses in general.

The accuracy of any census conducted is dependent on well-trained personnel which are called enumerators. It has been observed that if employees are not well-trained, the outcome or accuracy of even high-quality methods becomes unsatisfactory. As a result, trained and skilled personnel must be included in the census to ensure a satisfactory outcome. I have uploaded on the census types in the figure, you can go through it to get more idea on methods of census.

References: https://www.tandfonline.com/doi/pdf/10.1080/01621459.1937.10502323