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Climbing behaviour in extant crocodilians"Extant crocodilians are generally considered to be
predominantly or semi-aquatic. And, although the
role of terrestrial activity in their natural history is
increasingly recognized (see, for example, an overview
of terrestrial hunting in crocodilians in Dinets, 2011),
they are virtually never thought of as animals capable
of climbing. Their non-arboreality is often taken for
granted in various analyses of tetrapod limb evolution
and behaviour of extinct Archosauria (see BirnJeffery
et al., 2012, for a discussion of the subject
and a bibliography). Climbing behaviour in extant
crocodilians has never been described in detail in the
scientific literature, though it was briefly mentioned by
Tarsitano & Hecht (1980), Frey (1988), and, earlier,
Guggisberg (1972) who wrote that baby crocodiles “can
climb into bushes, up trees and even hang on reeds like
chameleons.”
Despite this limited documentation, the ability of
crocodilians (mostly juveniles) to climb trees is well
known to local residents in some locations. They
reported routinely observing basking in mangrove
trees by juvenile American crocodiles (Crocodylus
acutus) near Tulum (Quintana Roo, Mexico, Jason
Cleinsten pers. comm.), in mangrove trees up to 10 m
above ground by juveniles of the same species in Isla
de Salamanca National Park (Barranquila, Colombia,
Juan Cabrera pers. comm.) and by juvenile estuarine
crocodiles (C. porosus) near Sorong (West Papua,
Indonesia, Benyamin Syatfle pers. comm.). A photo
of a Nile crocodile (C. niloticus) climbing a low
tree trunk was obtained in March 2012 by Grant and
Dimari Oliver in Okavango Delta, Botswana (Larien
Spies pers. comm.). Photos of a juvenile New Guinea
crocodile (C. novaeguineae) basking on a tree trunk
growing at an angle were taken at Elevala River (Papua
New Guinea) by Michael Lech (pers. comm.). A photo
of a Philippine crocodile (C. mindorensis) in a tree
can be seen in van Weerd & van der Ploeg (2012).
Crocodiles (presumably Central African slendersnouted
crocodile Mecistops cataphractus, see notes
on taxonomy below) are reportedly often observed in
Odzala-Kokoua National Park (Republic of Congo)
as they bask in trees in very dense rainforest (Jackie
Appleton unpubl. obs.). Juvenile Siamese crocodiles
(C. siamensis) in Laos (Octávio Mateus pers. comm.)
and American alligator (Alligator mississippiensis) in
USA (Shawn Heflick pers. comm.) have been observed
on tree branches 0.5-1 m above the water. A photo of a
sub-adult American alligator perched on a tree branch
2-3 above the water (Fig. 1) was obtained at Pearl River
Delta, Mississippi (Kristine Gingras pers. comm.).
Captive dwarf crocodiles (Osteolaemus sp.) often climb
tree branches (Ralf Sommerlad pers. comm.). One adult
dwarf crocodile escaped from its enclosure at the Bristol
Zoo (UK) by climbing up a tree growing at an angle and
then over the barrier (John Dickson pers. comm.).
In most of these cases, crocodilians are observed
low above the water surface. But, as the following
observations show, they are capable of climbing higher,
sometimes into tree crowns."
herpetologynotes.seh-herpetology.org/Volume7_PDFs/Dinets_HerpetologyNotes_volume7_pages3-7.pdf
