RESULTS
We detected 38 species of mammals in the camera trap surveys, 27
occurring in the Middle Magdalena, 23 in the Orinoquia landscape, and 12
in both (Table S1). The probability of detection ranged from 0.09 to
0.90 in the MML and from 0.01 to 0.68 in the OL. In general, for shared
or similar species across landscapes, detection was higher in the MML,
with the exception of the tapir and ocelot. Occupancy rates varied from
0.09 to 0.99 across landscapes, with larger species like the giant
ant-eater, the puma and the tapir (> 30 Kg) having higher
occupancy rates in the OL, while smaller species like the agouti, paca
and armadillo had higher occupancy in the MML (Figure 1,
F1,16= 9.5, P=0.007).
The variables influencing occupancy differed from one landscape to
another. For species occurring only in the MML, the area of secondary
vegetation in the cell, distance to human settlements, and area of
forest were most determinant, while for those species occurring only in
the OL, distance to water, area of natural savannah and distance to
human settlements were the key predictors of occupancy (Figure 2). For
species occurring in both landscapes, the most important variable
influencing occupancy always changed from one landscape to another
(Figure 2). For medium-sized herbivore mammals and birds, occupancy was
influenced mainly by distance to human settlements and area of
artificial pastures in the MML (anthropic factors), while in the OL the
area of natural grassland, distance to water bodies, and area of
riparian forest were the most determinant factors (Figure 2). Carnivore
species were also influenced by distinct variables in each landscape.
For this group in the MML, occupancy rates were high in areas with more
forest, less artificial pasture, and away from human settlements. These
factors switched to area of natural grassland, distance to water and
distance to human settlements, respectively, in the OL (Figure 2).
Co-occurrence with another species was also important to determine
occupancy in some cases, reflecting inter-specific interactions (Table
1). Such interactions changed between landscapes, with the MML
presenting fewer interactions (zero values) and all of them positive
(occupancy of species B increases in the presence of species A). In the
MML the agouti increased its occupancy in the presence of the puma and
jaguar; the puma had a higher occupancy in the presence of paca and
jaguar, and the jaguar had a higher occupancy in the presence of paca
and puma. The paca itself was not affected significantly by the presence
of other species. In the OL, more combinations of species had
significant interactions, and some of them were negative. In this
landscape, the paca had higher occupancy rates in the presence of agouti
and puma, the agouti increased its occupancy in the presence of paca,
but decreased it in the presence of puma (negative interaction), and the
puma increased significantly in the presence of the paca but decreased
in the presence of agouti (Table 1). In most cases, species interactions
were mediated by another variable, which in the Middle Magdalena was
distance to human settlements (except for Jaguar-paca interaction)
(Figure 3). In the OL all interactions involving the agouti were
mediated by the area of riparian forests and the puma-paca interactions
by distance to water. Some of the relationships with the environmental
variable in turn, changed in the presence and absence of the
co-occurring species (Figure 3). The clearest example is forDasyprocta in the MML, where results indicate that its occupancy
is higher in the presence of Puma concolor and Panthera
onca . The relationship to the other important factor, distance to human
settlements, is positive in those cells with presence of these
predators, but it becomes negative (higher occupancy at smaller
distances to settlements) in their absence (Figure 3).