Congruence of local ecological knowledge (LEK)-based methods and line-transect surveys in estimating wildlife abundance in Amazonian forests

1) Effective estimation of wildlife population abundance is an important
component of population monitoring, and ultimately essential for the
development of conservation actions. Diurnal line transect surveys are one
of the most applied methods for abundance estimations. Local ecological
knowledge (LEK) is empirically acquired through the observation of
ecological processes by local people. LEK-based methods have only been
recognized as valid scientific methods for surveying fauna abundance in
the last three decades. However, the agreement between both methods has
not been extensively analysed. 2) We compared concomitant abundance data
for 91 wild species (mammals, birds and tortoises) from diurnal line
transects (9,221 km of trails) and a LEK-based method (291 structured
interviews) at 18 sites in Central and Western Amazonia. We used
biological and socioecological factors to assess the agreements and
divergences between abundance indices obtained from both methods. 3) We
found a significant agreement of population abundance indices for diurnal
and game species. This relationship was also positive regardless of
species sociality (solitary or social), body size and locomotion mode
(terrestrial and arboreal); and of sampled forest type (upland and flooded
forests). Conversely, we did not find significant abundance covariances
for nocturnal and non-game species. Despite the general agreement between
methods, line transects were not effective at surveying many species
occurring in the area, with 40.2% and 39.8% of all species being rarely
and never detected in at least one of the survey sites. On the other hand,
these species were widely reported by local informants to occur at
intermediate to high abundances. 4) Although LEK-based methods have been
long neglected by ecologists, our comparative study demonstrated their
effectiveness for estimating vertebrate abundance of a wide diversity of
taxa and forest environments. This can be used simultaneously with line
transects surveys to calibrate abundance estimates and record species that
are rarely sighted during surveys on foot, but that are often observed by
local people during their daily extractive activities. Thus, the
combination of local and scientific knowledge is a potential tool to
improve our knowledge of tropical forest species and foster the
development of effective strategies to meet biodiversity conservation
goals. --