6.
The recent all India tiger census counted all individuals above the age of 1 year as adults.
An earlier estimate four years ago included only individuals above the age of 1.5 years.
Given this information alone, can these two estimates be compared?
a. Yes, because the age of first reproduction in tigers has decreased due to pollution
b. No, because they are comparing different sets of tigers in the population
c. Yes, because these are random samples of the whole population
d. No, because many tigers die specifically between 1 and 1.5 years
No, the two tiger census estimates cannot be directly compared because they use different age thresholds for counting adults, leading to inconsistent population sets.
Option Analysis
Option a: Incorrect. No evidence links pollution to decreased tiger reproduction age; this assumes an unproven biological change rather than addressing methodological differences.
Option b: Correct. The recent census (tigers >1 year) includes 1-1.5-year-olds excluded in the prior estimate (>1.5 years), comparing overlapping but distinct population subsets.
Option c: Incorrect. Random sampling does not resolve differing definitions of “adults,” as the same tigers in the 1-1.5-year range appear in one but not the other.
Option d: Incorrect. Mortality between 1-1.5 years may exist, but the core issue is inclusion criteria, not survival rates alone.
All India Tiger Census age criteria changes raise key questions for wildlife ecology and CSIR NET Life Sciences aspirants: can estimates from surveys defining adults as >1 year (recent) and >1.5 years (four years prior) be compared? This methodological shift affects population comparisons in India’s tiger conservation efforts.
Tiger Census Methodology Basics
India’s All India Tiger Census, conducted every four years by NTCA and WII, uses camera traps and capture-recapture for tigers >1 year since 2018 (e.g., 2,967 tigers), versus >1.5 years in 2014 (2,226 tigers). Age is estimated via size relative to mothers or photos, excluding high-mortality cubs. This ensures survival-focused counts but complicates direct year-over-year analysis.
Why Comparison Fails
Different age thresholds mean the recent census includes 1-1.5-year sub-adults missed earlier, inflating numbers without reflecting true growth. Reports note this discrepancy explicitly, urging caution in trend assessments. For CSIR NET, recognize this as a sampling bias in population ecology.
| Census Year | Age Threshold | Estimated Tigers |
|---|---|---|
| 2014 | >1.5 years | 2,226 |
| 2018 | >1 year | 2,967 |
| 2022 | >1 year | 3,167-3,682 |
Exam-Relevant Insights
Option b best captures the issue: mismatched tiger sets violate comparability principles in quantitative ecology. Pollution (a) or mortality (d) are speculative; sampling (c) ignores criteria shifts. Master this for CSIR NET sections on ecology, evolution, and statistical analysis in biodiversity monitoring.
