AUTHORS: Jo Anne M. Smith-Flueck, Laboratorio de Teriogenología, “Dr. Héctor H. Morello” Facultad Ciencias Agrarias-Universidad Nacional del Comahue, Cinco Saltos, Río Negro, Argentina; Werner T. Flueck, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Río Negro, Argentina; Laura B. Borrelli, Laboratorio Microhistología, Instituto Nacional Tecnología Agropecuaria, EEA, Bariloche, Río Negro, Argentina
ABSTRACT: Even though only 350-500 Patagonian huemul (Hippocamelus bisulcus) remain in Argentina, information on their population ecology and dynamics is severely lacking. For the first time, radio-telemetry collars were placed on a group of huemul in Argentina to better understand the factors behind the population’s failure to recover. Six adult huemul (3 of each gender) were captured during the winter of 2017 at Shoonem Protected Park, Chubut province. Physical examinations of these six during the capture, plus a necropsy of a fresh female carcass found under a fallen tree, revealed all to be under 5 years of age, yet 86% with clinical pathophysiognomies [1] (Flueck & Smith-Flueck 2017), which included lameness, an affected hoof, and exfoliation of from 2-7 incisor teeth. Skeletal remains collected between 1993 and 2007 from this same population had already revealed a high prevalence of osteopathology [2](Flueck & Smith 2008), with at least 57% of the adults affected, with lesions of the mandibula (63%), maxillary (100%), and appendices (78%). Many of those mandibles were found lacking incisors and we attributed this to the natural decomposition process of skeletal remains, since single conical roots have little hold in the alveoli. Only now, through these live marked huemul, do we realize that the absence of incisors on those carcasses might have actually occurred before the animals’ died. Additionally, there is some preliminary evidence that this tooth-loss syndrome (TLS) might be a common phenomenon throughout other parts of the huemul’s distributional range. For example, aware of the discovery of TLS in Shoonem Protected Park, Chilean veterinarians, while treating abscesses on a male huemul in the wild in February of 2018, checked the oral cavity to discover that some of his incisors were also lacking. Moreover, he was thin and in poor physical condition [3]. In our study at Shoonem Protected Park, 5 of the 7 animals were missing teeth [1]. The worst case (Huemul #1), a young male of an estimated 4-5 years of age, had only one full incisor tooth remaining (Figure 1) at the winter capture, at which time palpation of the spine revealed a progressive stage of muscular atrophy. These would be animals for a rehabilitation center, would such a center be available [4]. But instead, as they are left to fend for themselves in the wild, we are concerned about their foraging efficiency. Limited by their disability, some type of modification to their feeding behavior must have occurred, which ultimately could affect the quality and quantity of aliments consumed. To determine if the diet of these tooth-lacking huemul is affected, we collected fresh fecal droppings from Huemul #1 in January, 2018 (summer). These feces were unusual in shape, texture, moisture and content, and not at all similar to average huemul pellets. Instead, the fecal matter appeared more like that of a horse or wild boar, and contained a bit of undigested fibers. Additionally, we collected fresh pellets from two other adult huemul in the same habitat type during the same week of fieldwork; these appeared more like normal deer feces, and from the size, also from males. After air-drying the specimens, plant content was determined using microhistological analysis [5,6] at the Instituto Nacional Tecnología Agropecuaria. The plant content of these samples is being compared with that of fecal pellets (n= 12) collected in the summer of 1999 in the same habitat at the same study area [7]. The 1999 samples showed huemul to be predominantly browse feeders, with woody species and forbs comprising 71.8% and 27.2% of the diet, respectively. The main two woody species in the diet were Maitenus disticha and Gaultheria spp., which comprised 54.4% and 8.4% of the diet, respectively. Given the rigid-textured, tiny leaves (5-15 mm in length) of these woody species, we do not expect this male huemul with TLS to be able to consume these types of plants, neither with help from the tongue. Normally deer press their bottom incisive teeth upon the upper dental pad to grab, pull and remove leaves from shrubs and forbs. Instead, we assume individuals with severe TLS, such as this male, might be forced to eat more tender plant material, such as forbs (those that predominated in the 1999 samples: Osmorhiza chilensis, Adenocaulen chilensis, and Rosaceae spp.), or instead focus on a completely different diet, perhaps foraging on aquatic species growing at the lake’s edge. During the winter capture, huemul were seen feeding on some submerged vegetation. We predict that this male with only 1 remaining incisive tooth has modified his diet to that of forbs over woody plants. Data from the three deer samples collected in January of 2018 will soon be ready for analysis and the results will be described and discussed in this presentation.
