Proceedings of the 18th Working Meeting of the Crocodile Specialist ...

7. Population estimates for each country in the species' range
Based on the previous calculations, the value of 3.16 ind./Km, was considered as an
overall index for Mexico (very close to the Mode and much lower than the average).
It was used to estimate total population size in Mexico as shown below:
7.1. Mexico
Abundance index used = 3.16 ind./Km (near Mode, from field data by COPAN).
Suitable habitat length, precautionary estimation by GARP-GIS = 25,227 Km.
Total animals estimated in the wild: 79,718 individuals.
Total of adults estimated in the wild (19% of total, proportion from COPAN Project):
15,146 individuals.
Similarly, with available published data, calculations were done for Guatemala and
Belize, as follows:
7.2. Guatemala
Abundance index used = 2.078 ind./Km (average of values cited by Lara, 1990).
Suitable habitat length inferred from literature data = 6,994.5 Km (from data on
extension and degradation of the Peten; Castañeda-Moya, 1998).
Total animals estimated in the wild: 13,911 individuals.
Total of adults estimated in the wild (19% of total, using proportion from Mexico as a
surrogate): 2,643 individuals.
7.3. Belize
Abundance index used = 2.63 ind./Km (from Platt, 1998).
Suitable habitat length inferred from geography = 3,347 Km.
Total animals estimated in the wild: 8,803 individuals.
Total of adults estimated in the wild (19% of total, proportion in Mexico as a
surrogate: 1,673 individuals.
8. A total wild population estimate
From data and calculations explained above, a tentative global figure of 102,432 (for
a downward rounding of ca. 100,000) individuals of all ages in the wild was
estimated for the whole range of the species. From this value, an estimated total of
19,462 (downward rounding of ca. 19,000) adult individuals were calculated. The
latter figure lends support to earlier considerations by experts made in the 1995
workshop and to subsequent work summarized by Ross (1998) departing from
consultations with experts, both indicating that in excess of 10,000 free adults were
thought to exist within the species’ range (see IUCN Red List, 2005, online).
9. Prospective dynamic modelling of potential population trajectory
Current data on natural history and fresh field information from COPAN on wild
populations, and from literature in the case of Guatemala and Belize, were input into
the Vortex 9.42 program (Lacy et al., 2003) to generate and initial exploratory
population trajectory model for C. moreletii.
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