(Rodentia: Caviidae) by the tropical rattlesnake Crotalus durissus

Herpetology Notes, volume 6: 277-279 (2013) (published online on 14 June 2013)
Predation of the spix’s yellow-toothed cavy, Galea spixii
(Rodentia: Caviidae) by the tropical rattlesnake
Crotalus durissus cascavella (Serpentes: Viperidae)
in the semi-arid region of Brazil
Kariny de Souza1,2, Rafael Damasceno Fernandes Coelho1,2, Paulo Mauricio Almeida Guimarães Reis1,2,
Patricia Avello Nicola1,2, Luiz Cezar Machado Pereira1,2 and Leonardo Barros Ribeiro1,2*
The neotropical rattlesnake, Crotalus durissus, is
distributed from southern Mexico to northern Argentina.
The habitat of these snakes encompasses semi-arid
regions, including dry and very dry tropical forests,
thorn bushes and relatively dry open areas, in addition
to a propensity to occupy areas degraded by human
activity (Campbell and Lamar, 1989). Despite their
wide geographic distribution, data on the natural history
and ecology of this species are scarce (Sant’Anna and
Abe, 2007).
The main traits of genus Crotalus are solenoglyph
fangs, presence of loreal pit and rattle at the tip of the tail.
These viviparous terrestrial snakes, whose diet consists
of vertebrates (Klauber, 1982), are predominantly
nocturnal, and can be found in burrows and among
debris (Martins and Oliveira, 1998). Crotalus durissus
cascavella (Fig. 1) is a snake native of northeastern
Brazil.
Rodents of the genus Galea belong to the family
Caviidae Gray, 1821, are endemic to South America
(Woods, 1982; Solmsdorff et al., 2004) and popularly
known as “preás” or “preás-do-campo” (spix’s yellowtoothed cavy). These rodents are characterized by their
medium-sized body covered by hair ranging in color
from gray to light brown, with body mass between 200
and 650 g, presence of periocular ring and absence of
1 Universidade Federal do Vale do São Francisco - UNIVASF,
Campus Ciências Agrárias, CEP 56300-990, Petrolina, PE,
Brasil.
2 Centro de Conservação e Manejo de Fauna da Caatinga
(CEMAFAUNA-CAATINGA), Universidade Federal do
Vale do São Francisco - UNIVASF, Rodovia BR 407, km 12,
Lote 543, s/nº - C1, CEP 56300-990, Petrolina, PE, Brasil.
*
Corresponding author; e-mail: [email protected]
a tail (Doutt, 1938; Díaz, 2000). They are terrestrial
animals with diurnal habits, but sporadically active at
night (Streilen, 1982a).
Galea spixii (Fig. 2) is widely distributed throughout
Brazil, from southeastern Pará to eastern Mato Grosso,
northwestern Minas Gerais, western Bahia, Pernambuco,
Paraíba and Rio Grande do Norte, southern Ceará, southcentral Piauí and Maranhão, in addition to the Federal
Figure 1. An adult male rattlesnake, Crotalus durissus
cascavella from the municipality of Cabrobó, Pernambuco,
Brazil. Photo: L.B. Ribeiro.
Figure 2. Adult specimen of spix’s yellow-toothed cavy,
Galea spixii. Photo: CEMAFAUNA-CAATINGA.
278
Figure 3. Dissection of Crotalus durissus cascavella for
removal of the stomach (top) and weighing of the snake’s
stomach containing the rodent Galea spixii (bottom). Photos:
P.M.A.G. Reis.
District (Moojen, 1952). They also occur in Paraguay
and Bolivia east of the Andes. Their habitat consists of
rocky outcrops, lowland caatinga and cultivated fields
in the Caatinga (Streilen, 1982b), as well as in areas of
the Cerrado (Bonvicino, Oliveira and D’Andrea, 2008).
Here, we report on the ingestion of G. spixii previously
unrecorded as prey for C. d. cascavella in the Caatinga
of north-eastern Brazil.
On 20 December, 2012, during a herpetological
expedition near the construction site of one of the water
conduction canals, part of the Integration Project of
the San Francisco River in the township of Cabrobó,
Pernambuco state, a specimen of C. d. cascavella was
found at 18:10 h among debris covered with cactus
vegetation (08°30’22.25”S, 39°28’1.91”W; 351 m elev.).
The snake was sighted after its presence was announced
by warning calls emitted by a group of white-naped jays
(Cyanocorax cyanopogon). The snake, which displayed
dilated stomach region, was collected and taken to the
Serpentarium of the Center for the Conservation and
Kariny de Souza et al.
Management of Caatinga Fauna (CEMAFAUNACAATINGA) in Petrolina, Pernambuco. The snake was
euthanized on 26 September with inoculation of 5 ml of
ketamine chloride (10%) associated with intraperitoneal
administration of xylazine chloride (2%).
At the Herpetology Laboratory we performed the
morphometry, and the snake was 789.0 mm snout-vent
length and total length of 815.8 mm. The specimen
was determined to be a male by hemipenis exposure.
Dissection (Fig. 3) revealed a subadult rodent in the
stomach identified as G. spixii. It was ingested headfirst and was found in an advanced state of digestion.
The head was partially decomposed, with the absence
of a number of bones such as the zygomatics. The
species was identified by analyzing cranial structures
such as the maxillary bones and the molariform series
anteriorly convergent, forming a “V” (Fig. 4). A deep
external notch was also absent on the second prism of
the PM (maxillary premolar), M1 (maxillary first molar)
and M2 (maxillary second molar), typical of Cavia, a
genus closely related with Galea (Rowe and Honeycutt,
2002).
The prey exhibited total length of 264 mm,
corresponding to 32.4% of total snake length. The
weight of C. d. cascavella after stomach content
removal was 360 g, and that of the stomach containing
G. spixii was 152 g, such that the rodent corresponded
to approximately 42% of snake body weight. Both
were deposited in the Herpetological Collection of the
Caatinga Fauna Museum at CEMAFAUNACAATINGA, under identification number MFCH
1841.
Figure 4. Maxillary fragment of the spix’s yellow-toothed
cavy, Galea spixii predated by Crotalus durissus cascavella,
illustrating the molariform teeth converging previously
forming a “V”. Photo: W. Lopes.
Predation of the spix’s yellow-toothed cavy, Galea spixii (Rodentia: Caviidae)
In a study by Sant’Anna and Abe (2007), of 343
prey items found in 259 C. durissus, 341 corresponded
to mammals, rodents being the most frequent, with
40 unidentified Rodentia, one unidentified Caviid,
and 223 Murids (Calomys sp. [99], Bolomys sp. [34],
Oligoryzomys sp. [33], Rattus sp. [26], Mus musculus
[12], Oryzomys sp. [4], Akodon sp. [12], Holochilus
sp. [2], Pseudoryzomys sp. [1]). Complementing the
total were 64 unidentified Mammalia, 13 Marsupialia
Didelphidae and two teiid lizards (Ameiva ameiva).
The highest occurrence of rodents as food items in
rattlesnakes may be owing to its nocturnal activity,
coincident with that of their prey.
The record of predation on G. spixii by C. d. cascavella
reported here suggests opportunistic predatory behavior,
with the ingestion of a relatively large prey in relation to
the snake’s size. This event may be due to the possibility
of prey scarcity in the dry season and the guarantee of
extensive fasting for the predator.
Acknowledgements. We thank the Ministério da Integração
Nacional for financial support, the Center for Conservation and
Management of Caatinga Fauna (CEMAFAUNA-CAATINGA)
for logistics support, and the Programa Institucional de Bolsas de
Iniciação Científica (PIBIC) which is sponsored by the Conselho
Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
for the research scholarship granted to K. Souza (Processes
103/2012 and 143744/2012-7). Collecting permits (Permit
95/2012 and Process 02001.003718/94-54) were granted by
Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais
279
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Accepted by Philip de Pous