Spectacled caiman - Caiman crocodilus

[Ceratodromeus]

Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Crocodilia
Family: Alligatoridae
Genus: Caiman
Species: C.crocodilus

Description
A  small to mid sized crocodilian, the Spectacled caiman averages a total body length of 1.5-2m(4.9-6.5ft), with the largest recorded male measuring 2.5m(8.2ft){1}. The heaviest recorded animal was a ~62kg(136lb){1} individual with a ~1.25 snout-ventral length(Approximate total body length of 2.5m).
The species is sexually dimorphic, with females being much smaller then males on average; measuring around 1.4m(4.5ft). In fact, a study conducted on a population in the Venezuelan Llanos shows this very well, Animals in the 70-79cm(2.2-2.5ft) snout-ventral demographic were predominately females(~73% of the sample), while animals measuring 90+cm(2.9+ft) in snout-ventral length were exclusively male{1}. Its common name derives from a bony ridge which is present between the front of the eyes, appearing to join the eyes like a pair of spectacles.  This species is often confused with the Yacare caiman (Caiman yacare), but can be distinguished by its lighter body coloration, and the Spectacled caiman lacks the dark barring on the lower jaw seen in the Yacare caiman. The latter species was at one point considered a subspecies of the former, but has been promoted to species level in recent years.

Geographic distribution and habitat
This is a very wide-spread, successful species. Despite having their numbers depleted via hunting for the leather trade, the Spectacled caiman is a common animal throughout it's distribution. They can be found in Central America, and down through Central South America, such as the Venezuelan Llanos population. It is saltwater tolerant, sometimes being found in brackish waters. They are adaptive animals, being found in riverine habitats throughout their range.

Dietary habits
Like other Crocodilian species, the Spectacled caiman is a dietary generalist. The bulk of their diet consists of an array of insects (Coleoptera, Orthroptera, Hymenoptera, Homoptera), Crabs(Valdvia, Poppiana), Fish(Hoplosternum,Characidae), Small reptiles (Caiman, Hydrops,Bothrops) and mammals(Lontra, Alouttra, Hydrocheorus). They have been known to scavenge, but will usually hunt down and eat their own food. Young animals go through an ontogenic dietary change at the onset of maturity, incorporating more vertebrate animals in their diet{1,2}. Fish are a significant part of the caiman's die, especially in the dry season. They have adopted fascinating behaviors in acquiring this sort of prey, either propelling themselves out of the water, only to splash down and stun their intended prey, or herding their prey with their tails toward their jaws{3}.

Reproduction
Spectacled caiman mature at approximately 4-7 years of age; males are typically sexually mature at young ages and larger sizes then females are but may not reproduce due to social pressures/constraints{4}. In the Venezuelan Llanos, Reproductory habits have been tied to the start of the wet season; mating occuring anywhere from May- August. A clutch size is tied to the snout-ventral length of the female, with longer females producing larger clutches. Females construct their nests using material from their chosen nesting sites, which are typically close to the waters' edge. These nests will be about 1m(3.2ft) high, 1m(3.2ft) long, and 44cm(1.4ft) wide -- based off of a sample of 22 nests{5}. The eggs hatch anywhere from October-December, depending on when the clutch was laid. The young stay in creches, near their mother for many weeks afterwards. They are very vulnerable at this stage, and most of the hatchlings will not survive -- being picked off by  indigo snakes,conspecific adults, turtles, herons, storks, pigs, ocelots, and predatory fish. Adults have their fair share of predators as well, Green anacondas, Black caiman, Orinoco crocodiles, American crocodiles, and Jaguars are all known predators of adults{6}.



References
{1} Staton, MARK A., and JAMES‘R. Dixon. "Studies on the dry season biology of Caiman crocodilus crocodilus from the Venezuelan Llanos." Mem. Soc. Cienc. Nat. La Salle 35.101 (1975): 237-265.
{2} Da Silveira, Ronis, and William E. Magnusson. "Diets of spectacled and black caiman in the Anavilhanas Archipelago, Central Amazonia, Brazil." Journal of Herpetology (1999): 181-192.
{3} Schaller, George B., and Peter Gransden Crawshaw Jr. "Fishing behavior of Paraguayan caiman (Caiman crocodilus)." Copeia (1982): 66-72.
{4}Thorbjarnarson, John B. "Reproductive ecology of the spectacled caiman (Caiman crocodilus) in the Venezuelan Llanos." Copeia (1994): 907-919.
{5} Staton, Mark A., and James Ray Dixon. Breeding biology of the spectacled caiman, Caiman crocodilus crocodilus, in the Venezuelan Llanos. US Department of the Interior, Fish and Wildlife Service, 1977.
{6} Gorzula, Stefan, and Andres Eloy Seijas. "The common caiman." Crocodiles: Their ecology, management, and conservation. IUCN Publ. New Series, Gland, Switzerland.[Links] (1989): 44-61.

[Ceratodromeus]

dietary data on an invasive population in Puerto rico

Diet of the non-native spectacled caiman (Caiman crocodilus) in Puerto Rico
The spectacled caiman (Caiman crocodilus) was introduced to Puerto Rico over 50 years ago with the Tortuguero Lagoon Natural Reserve
(TLNR) as its epicenter, where it is now established as an apex predator. Although concerns have been raised regarding the potential impact
of this naturalized predator on Puerto Rico’s native fauna, little was known of the caiman’s diet on the island. Therefore this study was
conducted to determine the diet of the spectacled caiman and its potential impact on island animals. For this study, measurements were
obtained from 138 caimans across all life stages (12–94 cm snout–vent length; SVL) from October 2014 to May 2015 within the TLNR.
Stomach contents were retrieved and analyzed based on prey category occurrence frequency. In addition, caiman muscle samples were
obtained to determine their nitrogen and carbon isotopic signature. Insects were the most abundant prey items encountered with 90.7% and
68.8% in hatchling (SVL < 20 cm) and juvenile (SVL = 20–59.9 cm) stomach respectively. In adult (SVL > 60 cm) caimans, fish remains
were the most significant prey items with 38.3% frequency of occurrence. Fish, insects, and gastropods were the only categories of ten
designated prey categories to show significant variation among the three caiman age classes. This study provides novel information on
dietary habits of spectacled caimans in Puerto Rico relevant to the design of management strategies.



www.reabic.net/journals/mbi/2016/Accepted/MBI_2016_Bontemps_etal_correctedproof.pdf

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note on the dietary habits of the introduced population of southern florida -- good to see one intro'd species feeding on others

[Ceratodromeus]

A fascinating description of the musculature in the chest & limbs of two young adult males

MUSCULAR ANATOMY OF THE PECTORAL AND FORELIMB OF Caiman crocodilus crocodilus (LINNAEUS, 1758) (CROCODYLIA: ALLIGATORIDAE)
Abstract
Among the Brazilian crocodilian, Caiman crocodilus crocodilus is widely distributed, given its adaptation to diverse habitats and their generalist diet. Information about the reproductive and ethological character of this species is abundant, whereas morphological data are still scarce. This study aimed to identify and report the muscles and their origin and the insertion into the pectoral and forelimb of C. crocodilus crocodilus. We used two male specimens, adults, belonging to the collection of the UFG - Jataí. We performed usual procedures for dissection and further individualization, withdrawal of members, and observation of muscle origins and insertions. The musculature of C. crocodilus crocodilus generally conservative is similar to C. latirostris and A. mississippiensis. The muscles of the pectoral girdle showed little variation among crocodilians. In the forelimb, the triceps muscle has five distinct heads and biceps has only one. The extensor and flexor surface of the hand showed similar topography to A. mississippiensis. We described some differences in the origin and insertion of certain muscles, as well as the classification and topography of some flexor and extensor muscles in the forearm segment. The distal segments showed more variations, which probably reflects the variety of locomotor habits among crocodilians.


Figure 1
Pectoral and Forelimb of the Caiman crocodilus crocodilus, lateral view (A). Pe, pectoralis; Scl, supracoracoidus longus; De, deltoideus scapularis; Dc, deltoideus clavicularis; Le, levator scapulae; Cbv, coracobrachialis brevis ventralis; Rm, teres major; Sv, serratus ventralis; Br, brachialis; Bi biceps brachii; Tlc, triceps longus caudalis; Eu, extensor carpi ulnaris; Er, extensor carpi radialis; Fu, flexor ulnaris. Medial view (B). Se, subscapularis; Ro, rhomboideus; Tla, triceps longus lateralis; U, Humeroradialis; Pr, pronator teres; Fld, flexor digitorum longus; Flc, flexor carpi ulnaris.
Scale Bar = 1cm.


Figure 2 Antebrachium of the Caiman crocodilus crocodilus, lateral view (A). Tlc, triceps longus caudalis; Ar, abductor radialis; Sp, supinator; Eu, extensor carpi ulnaris; Pq, pronator quadratus; Fu, flexor carpi ulnaris; Erc, extensor carpi radialis brevis; Erl, extensor carpi radialis longus. Medial view (B). Flc, flexor ulnaris; Fld, flexor digitorum longus; Pr, pronator teres; Bi, biceps brachii. ScaleBar = 3cm.

www.scielo.br/scielo.php?pid=S1809-68912016000200285&script=sci_arttext

[Ceratodromeus]

A man and his 2.1m, 46kg caiman

[Ceratodromeus]

Diet, Gastric Parasitism, and Injuries of Caimans (Caiman,
Melanosuchus, and Paleosuchus) in the Peruvian Amazon
Abstract
Caimans (Crocodilia: Alligatoridae) are top-level predators in aquatic ecosystems of the Neotropics. This paper presents data on
the diet of caimans from the Peruvian Amazon (principally Paleosuchus spp., but also Caiman crocodilus and Melanosuchus niger), including
feeding observations and stomach content examinations. A total of 58 stomach content analyses and three in situ feeding observations were
made, and incidence of gastric parasitism and external injury were also studied. Insects, crustaceans, and fish were the most frequently
encountered prey in the gut of P. trigonatus, but reptiles, fish, crustaceans, and mammals composed the greatest proportion of the diet by
stomach content dry mass. We report novel squamate and fish species in the diet of Amazonian caimans and overall dietary findings consistent
with that of other caiman diet literature. Gastroliths were absent from C. crocodilus and M. niger, although 44% of P. trigonatus sampled
contained gastroliths. Parasitic nematodes were recovered from just under half of sampled C. crocodilus and P. trigonatus and 71% of M. niger.
Injury rates were low in M. niger and P. trigonatus (< 10% of individuals) while 35% of C. crocodilus were injured, most often through damage
to the tail. These data on caiman diet, gut parasitism, and injury rates help provide a baseline for comparison between species and study
populations.

"Bodily injuries were observed in 35% Caiman crocodilus,
8% of Melanosuchus niger, and 10% of Paleosuchus
trigonatus. There was no apparent sex bias in injury rates
of any species (Table 4). Damage to and blunting of the
tail were the most commonly observed injury in C. crocodilus
and M. niger. None of the captured P. trigonatus exhibited
tail injuries, although one male (SVL = 34.5 cm,
TL = 67.2 cm, M = 0.9 kg) had severe damage to the left
forelimb resulting in a partially amputated foot bearing
a single intact phalange. Among all captured individuals,
only a single live female C. crocodilus (SVL = 41.2 cm,
TL = 81.1 cm, M = 2.2 kg) exhibited a bleeding puncture
wound on the posterior of the skull, in addition to the recent
loss of ~ 10 cm of distal tail length."



www.researchgate.net/profile/Patrick_Moldowan2/publication/312029690_Diet_Gastric_Parasitism_and_Injuries_of_Caimans_Caiman_Melanosuchus_and_Paleosuchus_in_the_Peruvian_Amazon/links/586ad03c08ae6eb871ba72d2.pdf

[Ceratodromeus]

Nest attendance influences the diet of nesting female spectacled caiman (Caiman crocodilus) in Central Amazonia, Brazil
Abstract
Although nesting ecology is well studied in crocodilians, there is little information on the diet and feeding habits of nesting
females. During the annual dry season (November–December) of 2012, we studied the diet of female spectacled caiman
(Caiman crocodilus) attending nests (n=33) and far from nests (n=16) in Piagaçu-Purus Sustainable Development Reserve (PPSDR),
Central Amazonia, Brazil. The proportion of empty stomachs in nest-attending females was larger, and the occurrence
of fresh food items was lower when compared to females not attending nests. Fish was the most frequent prey item for
non-nesting females, while terrestrial invertebrates and snail operculae were the prey items most commonly recovered from
stomachs of nesting females. Our study demonstrates that, despite enduring periods of food deprivation associated with
nest attendance, nesting females of C. crocodilus still consume nearby available prey, possibly leaving their nest temporarily
unattended.


Fig.2. Incidence of empty stomachs (A) and fresh food
items (B) in Caiman crocodilus nesting (n=33) and nonnesting
females (n=16) in PP-SDR.


"Total mass of stomach contents in nesting and nonnesting
females was 208 g (mean=8.5±11.6) and 207 g
(mean=13.3±11.4), respectively. Plant material occurred
in stomach contents of 62% of nesting females and 72%
of non-nesting females, representing about 27% and 2%
of the total mass, respectively. About 24% of stomachs of
nesting females were empty (Fig. 2A), while stomachs of
all non-nesting females contained at least one food item
(U=234.0; p<0.05). The number of food items in nesting
females ranged between 1 and 8 (mean=3.2±1.9), and
was significantly less (U=112.5; p<0.02) than the number
encountered in non-nesting females (ranging between 1
and 26 (mean=7.9±7.5).
Recently ingested food items were found in only 39%
of stomach contents of nesting females (Fig. 2A), whereas
all non-nesting females had recently ingested prey items
in their stomachs (U=84; p<0.05). A total of 206 prey
items were identified, 70% of which were terrestrial
invertebrates, 15% were fish, 8% were molluscs, 5% were
aquatic invertebrates and 2% were other vertebrates
(Table 1).

Table 1. Occurrence (O), percent occurrence (%O), frequency (N) and relative frequency (%N) of prey items found in
stomach contents of nesting and non-nesting females of Caiman crocodilus in PP-SDR. Prey items grouped into five
prey categories: Terrestrial Invertebrates (TI), Aquatic Invertebrates (AI), Molluscs, Fish or Other Vertebrates (OV).


www.researchgate.net/publication/283073843_Nest_attendance_influences_the_diet_of_nesting_female_spectacled_caiman_Caiman_crocodilus_in_Central_Amazonia_Brazil