Diet, growth and movements of juvenile crocodiles Crocodylus porosus Schneider in the Klias River, Sabah, Malaysia

Abstract

A total of 14 spotlight surveys were carried out from January 1992 to February 1993 along 37 km of the Klias River in north-western Sabah, Malaysia. Surveys were at low tide between 1900 and 0600 h from a survey boat at 15 km h−1 by two observers. A total of 221 sightings were made, which varied between 2 and 29 per survey (mean 15.8). A total of 55 juvenile crocodiles were captured, with 16 recaptures. Calculated density was 0.9–1.8 individuals km−1, while the estimated crocodile population was 46.1 ± 10.2 (SD) for the survey area. Percentage sightings according to total length were: 42% ≤0.5 m; 40% >0.5-≤1.0 m; 5% > 1.0-≤3.0; and 13% eyes only. Recapture of 16 tagged juveniles suggested that hatchlings ≤0.5 m total length remained within >0.5 km of their release point for at least one month, and juveniles 0.5-≤1.0 m more than one year. Hatchlings had growth rates between 0.01 and 0.08 cm d−1 and 0.3 and 1.5 g d−1, while larger juveniles grew at least 0.11 cm d−1 and 2.7–2.9 g d−1. Stomachs of hatchlings and juveniles contained crabs (Ocypodidae), prawns (Atyidae), insects and small fish (Hemiramphidae). Relatively large numbers of juvenile Crocodylus porosus (82.4%) in the Klias River suggests that the area, though under hunting pressure, is desirable as a site for the conservation of C. porosus in the Sabah.

Feeding across the food web: The interaction between diet, movement and body size in estuarine crocodiles (Crocodylus porosus)

“…In contrast, the small‐sized individuals had large WIC : TNW ratios for their tissue c δ 13 C compositions. This result suggests that small‐sized individuals trophically link different habitats, as reported in other populations where they consume tiny fish from aquatic habitats and insects from terrestrial habitats (Sah & Stuebing ). Because of the high connectivity among habitats within these wet‐dry tropical landscapes, mediated by fish and other mobile prey (Jardine et al .…”

“…This study complements anecdotal observations and stomach content analyses by demonstrating that body size predicts the diet of C. porosus (Taylor ; Kar & Bustard ; Webb & Manolis ; Webb et al . ; Sah & Stuebing ). The study further shows that not only do C. porosus become trophically linked to primary producers in different habitats as they grow, but medium‐ and large‐sized individuals also specialize on different prey within these food webs.…”

“…Taylor ; Webb et al . ; Sah & Stuebing ; Whiting & Whiting ). These methods have identified many of the animals that C. porosus consume (Taylor ; Kar & Bustard ; Webb & Manolis ; Webb et al .…”

“…These methods have identified many of the animals that C. porosus consume (Taylor ; Kar & Bustard ; Webb & Manolis ; Webb et al . ; Sah & Stuebing ; Whiting & Whiting ). However, they suffer from biases in digestion time and seasonal availability (Jackson et al .…”

A Checklist of Host-Parasite Interactions of the Order Crocodylia

“…Sah and Stuebing (1996) stated that gut contents from C. porosus contained parasites, but parasites were not identified. Caimanicola marajoara Teixeira de Freitas and Lent 1938.…”