Diet of Dendropsophus microcephalus and Scarthyla vigilans (Anura: Hylidae) at a locality in north-western Venezuela with notes on microhabitat occupation

from  S.  vigilans (12 males, 18 females, 1 juvenile); 

14 stomachs of D. microcephalus and 23 of S. vigilans 

were empty and the remaining 91 stomachs had ex-

tremely digested contents which did not allow identi-

fication (D. microcephalus = 35; S. vigilans = 56); one 

stomach of D. microcephalus contained no more than 

seeds. We found 1.61 ± 0.88 prey items per stomach 

in D. microcephalus corresponding to a total volume 

of 7.71 ± 13.48 mm3 (min-max: 0.14-62.38 mm3). 

In S. vigilans we found, on average, 1.48 ± 0.996 prey 

items per stomach, corresponding to a total volume of 

18.03 ± 27.97 mm3 (min-max: 0.44-128.70 mm3). 

We did not find significant differences in prey size 

(Mann-Whitney U: Z = -0.680, p = 0.5) or volume 

(Z = -1.705, p = 0.1) between species.

We identified 36 prey categories (32 up to fam-

ily, 4 up to order) of arthropods of Cheliceriformes, 

Unirramia and Crustacea (Table 1); 30 categories in 

D. microcephalus and 21 categories in S. vigilans. With 

regards to numeric representation, the diet of D. mi-

FIGURE 1:

 Principal components analysis of diet composition of Dendropsophus microcephalus and Scarthyla vigilans. (A) Based on nu-

meric composition (number of items per prey category), (B) Based on volumetric composition (volume of each prey category). x: S. vigilans, 

+: D. microcephalus.

Fonseca-Pérez, K.A. 

et

 

al

.: Diet and microhabitat Hylinae

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crocephalus was composed of (in descendent rank; 

only categories with n > 3 items are listed) Tachinidae, 

Agelenidae, Cicadellidae, Lepidoptera (larvae and 

adults), Tetragnathidae, Chrysomelidae, Formicidae, 

Blattidae and Derbidae; 20 additional categories had 

less than 3 items as a whole (Table 1). With regards to 

the frequency of apparition (number of stomachs), the 

most frequent categories were Agelenidae, Cicadelli-

dae, Tachinidae, Lepidoptera-larvae, Chrysomelidae, 

Formicidae, Tetragnathidae, Blattidae and Derbidae. 

As a whole, the most important categories (%RII) 

were Agelenidae (11.1%), Tachinidae (9.32%) and 

Lepidoptera-larvae (7.96%).

On the other hand, the diet of S. vigilans was 

composed of (numerical rank, n  >  3 items) Grylli-

dae, Tachinidae, Cicadidae, Cicadellidae, Lycosidae, 

Delphacidae and Lepidoptera; 14 additional catego-

ries had less than 3 items (Table  1). Regarding the 

frequency of apparition, the most frequent catego-

ries were Cicadellidae, Cicadidade, Gryllidae, Tach-

inidae, Delphacidae and Lepidoptera. As a whole, 

the most important categories (%RII) were Gryllidae 

(14.13%), Cicadidae (9.1%), Cicadellidae (8.3%) 

and Delphacidae (8.02%).

The diversity of the diet of D.  microcephalus 

(H’) was 3.18, the equitability (F) was 0.76 and niche 

breath (B

α

) was 0.467. The diversity of the diet of 

S.  vigilans was 2.89, the equitability was 0.82, and 

niche breath was 0.65. Hutchenson’s t indicated that 

diet diversity differed significantly between species 

(t = 2.16, p = 0.03), being larger in D. microcepha-

lus than in S. vigilans. Niche overlap (O) between the 

species was 0.316.

The PCA performed with the numeric compo-

sition confirmed moderate diet overlap between the 

species (Fig. 1A), while that performed with volumet-

ric data indicated slight overlap (Fig. 1B). Nonethe-

less, the first two components (PC1 and PC2) only 

explained 50% of the variance, both numerically and 

volumetrically (Table  2). Numerically, Tachinidae 

was the most important category in PC1 and Gryl-

lidae and Cicadellidae were in PC2 (Fig. 1A, Table 2). 

Volumetrically, Acrididae was the most important cat-

egory in PC1 and Gryllidae and Lepidoptera in PC2 

(Fig. 1B, Table 2).

Microhabitat occupation

We recorded habitat occupation from 95 indi-

viduals of D. microcephalus (31 males, 3 females, 9 ju-

veniles, 52 unknown sex) and 94 individuals of S. vigi-

lans (10 males, 7 females, 8 juveniles, 69 unknown 

sex). All the individuals of both species were perched 

on emergent vegetation inside the lagoon at the mo-

ment of sight (none individual was observed perching 

on soil, on floating vegetation or at the lagoon margins 

above dry soil), on leaves and stems of Monocotyle-

dons and Dicotyledons with the same probability 

(

χ2 = 1.021, p > 0.05, d.f. = 3). They perched at an 

average height of 24 ± 16.2 cm (min-max: 5-54 cm) in 

S. vigilans, and of 22.7 ± 9.5 cm (min-max: 0.5-93 cm) 

in D. microcephalus. Despite the fact that D. microceph-

alus occupied a wider range of heights (Fig. 2), verti-

cal distribution was homogeneous between species (10 

height classes, defined every 10 cm from 0 to 100 cm; 

χ2 = 9.52, p > 0.05, d.f. = 7, Fig. 2). Both species were 

more common from 21 to 30 cm than at other height 

intervals; therefore, microhabitat preferences coincide.

FIGURE 2:

 Vertical distribution of individuals of Dendropsophus 

microcephalus and Scarthyla vigilans on emergent plants.

TABLE  2:

 Eigenvalues of prey categories, numerically and 

volumetrically, for the first two principal components (PC1 and 

PC2) of Dendropsophus microcephalus and Scarthyla vigilans. The 

most important category for each PC is shown in bold.

Prey category

Number of items

Volume of items

PC1

PC2

PC1

PC2

Agelenidae

-0.052

0.077

-0.018

-0.035

Ctenidae

-0.011

-0.002

-0.001

-0.001

Lycosidae

0.115

-0.033

-0.009

-0.063

Salticidae

-0.011

-0.012

-0.001

-0.001

Chrysomelidae

-0.031

-0.015

-0.008

-0.015

Tachinidae

0.984

0.049

-0.010

-0.023

Cicadellidae

-0.069

-0.369

-0.008

-0.020

Cicadidae

-0.038

0.178

-0.007

0.051

Delphacidae

-0.026

-0.026

-0.013

-0.023

Formicidae

-0.033

-0.051

-0.001

-0.003

Noctuidae

-0.009

-0.008

-0.005

-0.008

Lepidoptera-larvae

0.028

-0.136

-0.043

-0.268

Acrididae

-0.009

-0.008

0.997

0.037

Gryllidae

-0.066

0.891

-0.053

0.957

Tettigonidae

-0.013

-0.069

-0.002

-0.004

Papéis Avulsos de Zoologia, 57(7), 2017

99

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