Contributions to Zoology, 86 (2) – 2017Marta Guntiñas; Jorge Lozano; Rodrigo Cisneros; Carlos Narváez; Jorge Armijos: Feeding ecology of the culpeo in southern Ecuador: wild ungulates being the main prey

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Results

We identified a total of 413 prey items in 304 scats (Tab. 1), collected during a year of sampling. A total of 16 mammalian species were identified, which were by far the most consumed prey. Indeed, mammals were present in 100% of the scats analysed. Cervids were the most consumed prey group, with a frequency of occurrence (FO) of 71%. The next most significant group in terms of FO was small mammals (26%), followed by big rodents (12%), carnivorous (10%) and rabbits (8%) (Tab. 1). Birds and fruits were poorly represented, both being found in only 3% of the scats analysed. Contributions of consumed biomass in terms of percentage were similar, except for small mammals (0.95% CB), others (0.11% CB) and fruits (0.02% CB), with values much lower than those provided by FO.

Considering prey species, the little red brocket deer (M. rufina) showed the highest FO, followed by the northern pudu (Pudu mephistophiles). The most consumed small mammals were marsupials: the gray-bellied shrew opossum (Caenolestes caniventer) and the silky shrew opossum (C. fuliginosus). Big rodents were also important for the Andean fox’s diet, especially the spotted paca (Cuniculus paca) and the central american agouti (Dasyprocta punctata). The tapeti or forest rabbit (Sylvilagus brasiliensis) is the only lagomorph present in the region and it also preyed upon (8.2% FO). The nine-banded armadillo (Dasypus novemcinctus) also appeared in the diet (1.32% FO). A focal point of the culpeo’s diet was the relatively high consumption of carnivores and similar (i.e. Didelphidae), such as the western mountain coati (Nasuella olivaceae), the striped hog-nosed skunk (Conepatus semistriatus), and opossums (Didelphis marsupialis and/or D. pernigra), accounting for 9.8% FO. Interestingly, remains of puma (Puma concolor) were also found in three scats (Tab. 1).

Temporal variation was found in the most consumed group (i.e. cervids) (n = 217, G = 19.7, d.f = 10, p = 0.03), where the highest consumption occurred during April, May and June (Fig. 2). Likewise, in the second most consumed group, small mammals, temporal variation was also found (n = 80, G = 27.92, d.f = 10, p = 0.002), with an intense consumption in August (Fig. 2). For the forest rabbit a higher consumption during April and June was recorded, showing a marginally non-significant difference (n = 25, G = 17.46, d.f. = 10, p = 0.06). For the rest of the prey groups no temporal variations in consumption were found: big rodents (n = 37, G = 10.10, d.f = 10, p = 0.43), carnivorous (n = 30, G = 14.1, d.f = 10, p = 0.17), armadillos (n = 4, G = 5.48, d.f = 10, p = 0.86), fruits (n = 9, G = 14.12, d.f = 10, p = 0.16) and others (n = 11, G = 7.00, d.f = 10, p = 0.72). Over time significant negative Spearman correlations were found between the consumption of deer and small mammals (January = -0.54, p < 0.05; March = -0.52, p < 0.05: August = -0.55, p < 0.05; September = -0.67, p < 0.05), as well as between the consumption of deer and rabbits (February = -0.79, p < 0.05; April = -0.54, p < 0.05).

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Figure 2. Frequency of occurrence (FO) across months of the culpeo’s prey groups showing temporal variation in the high areas of the Podocarpus National Park (PNP): cervids, small mammals and rabbits. In brackets the number of scats found per month is shown.

In relation to the annual average contribution of biomass there was a significant difference between prey groups (H(6, N = 77) = 55.46; p < 0.001), given that a high cervid contribution was found (Fig. 3). Big rodents, rabbits and carnivorous were the next most significant groups, showing similar contributions (around 10% CB). Finally, contribution to consumed biomass by the resting groups was minimal. Throughout the year a clear predominance of deer consumed biomass is observed, which decreases in March just when the biomass contribution of big rodents and carnivorous increases (see Fig. 4). Although in variable values, rabbits, carnivorous, and big rodents provided biomass in considerable amounts during all months, whereas the contribution of small mammals and other food items was always very low (Fig. 4).

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Figure 3. Annual average of prey group contributions in estimated consumed biomass (CB, expressed as percentage) to the culpeo’s diet in the high areas of the Podocarpus National Park (PNP, southern Ecuador).

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Figure 4. Contribution in estimated consumed biomass (CB, expressed as percentage) across months of the culpeo’s prey groups in the high areas of the Podocarpus National Park (PNP, southern Ecuador).

In addition, values given by the Shannon-Wiener’s index as a measurement of the culpeo’s trophic diversity fluctuated throughout the year, showing an average of 1.7. January presented the lowest diversity value (1.2), whereas it doubled in March (2.2) (Fig. 5).

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Figure 5. Trophic diversity of culpeos across months in the high areas of the Podocarpus National Park (PNP, southern Ecuador), according to the Shannon-Wiener’s index. In brackets the number of prey items per month is shown.