EXPEDITION REPORT 2007 - Biosphere Expeditions

2.5. Discussion & Conclusions
2.5.1. Jaguar, puma and ocelot presence
The fact that jaguars and ocelots were detected once in a quadrat and then not detected
again in the same quadrat meant, for occupancy calculations (PAO), that their detection
(or capture) probabilities were less than 1. In contrast, if a species is detected at a given
quadrat in every sampling occasion, its detection probability equals 1, i.e. it will always be
recorded when present.
Jaguars and ocelots were recorded fewer times than puma. However, their resulting low
capture probability produced a proportion of area occupied (PAO) of 100% in the software
PRESENCE or, in other words, the jaguar and the ocelot were considered to be present
everywhere. This result may appear counterintuitive at first, as these two species could
arguably be considered rare, because it was so difficult to detect them. Calculations of
PAO, however, based on the capture history, take into account that the jaguar and ocelot
were very difficult to detect in the study area, even when present. In fact, the capture
history shows that they were detected only once in each quadrat where they were found.
To PRESENCE, the fact that it was so difficult to detect them, even in the quadrats where
they were present, meant that they may have gone largely unnoticed in the other quadrats,
i.e. they might have been actually present over the entire study area, but with such a
cryptic behaviour that they were not detected.
It may be easier to understand the way PRESENCE has estimated jaguar and ocelot
presence by looking at the contrasting results of puma, which had the maximum detection
probability (p=1). The puma was easy to detect where it was present, being easily
‘recaptured’ where it was recorded. PRESENCE results considered that the puma could
be detected in every quadrat that it was present, so the number of quadrats where it was
found (naïve estimate of occupancy) corresponded exactly to its PAO (calculated
occupancy).
The results for puma are consistent with those in the highlands of southern Brazil, where
pumas were found to be one of the easiest species to detect when present, provided
adequate substrate for track imprinting was available (Mazzolli 2006). Unfortunately,
jaguars no longer inhabited the area, impairing comparisons. However, the PAO results for
jaguar in the Guaratuba bay are unlikely to be accurate, as the species is also known to
roam over relatively open trails and along beaches rather than in dense forest (Schaller
and Crawshaw 1980) and on undisturbed roads and open trails (Meffei et al. 2004) like the
puma. Thus, if present, the jaguar was expected to have left enough tracks to be
repeatedly detected during the intensive surveys.
The literature has only vague information on capture probabilities of jaguar from tracks or
other signs, partially due to the fact that capture probabilities using signs as evidence are
quite a new methodology (see Mackenzie et al. 2002). What’s available are probabilities
used to calculate abundance using CAPTURE (e.g. Maffei et al. 2004, Soisalo and
Cavalcanti 2006) not directly comparable with those from PRESENCE. Empirical evidence
indicate, however, that signs may be regularly found (Schaller and Crawshaw 1980,
Rabinowitz 1986) including near the current study area (Leite & Galvão 2002) and may
even be more frequent than those of puma (Silveira et al. 2003).
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