Niche segregation between guanacos and cattle in grasslands and Nothofagus antarctica forests under silvopastoral use estimated using camera traps.

G MARTÍNEZ PASTUR; R SOLER ESTEBAN; JM CELLINI; HA BAHAMONDE; PL PERI; MV LENCINAS

Evora

Congreso; World Congress Silvo-pastoral Systems.; 2016

University of Evora

Natural grasslands and Nothofagus antarctica (ñire) forests in Tierra del Fuego are under pastoral use, where competition for limiting resource (food) exists between native population of Lama guanicoe (guanaco) and managed population of Bos taurus (cattle). The objective was to determine the existence of niche segregation between guanacos and cattle in natural grasslands and ñire forests under silvopastoral uses, and to identify different temporal patterns. Digital camera traps with solar panels were set up in grasslands (n=4) and ñire forests (n=8) during one year-round, with a delay of five minutes between photo-takings. Animal counting and area of effective capture of each photo allowed us to estimate a relative density index (RDI, number observations.day-1.hectare-1). Finally, percentage of observations across the day for each species was calculated for each treatment. A total of 3520 photos with 5660 individuals in grasslands and 177 photos with 197 individuals in ñire forests were obtained. Cattle occurrence was from November to February being greater in grasslands (RDI 2.87-2.65-4.84-0.08 obs.day-1.ha-1, respectively) than in forests (RDI 0.05-0.13-0.10-0.09 obs.day-1.ha-1, respectively), while guanacos used the area all year-round but with different RDI between winter and summer (RDI 0.15-0.53 obs.day-1.ha-1 in grasslands and 0.69-0.51 obs.day-1.ha-1 in forests, respectively). In both treatments guanaco RDI decreased when cattle RDI increased, showing clear niche segregation between species. Beside this, guanacos used grasslands in warmer periods during the day (29% 6-12 hs, 68% 12-18 hs) while cattle grazed until sunset (42% 6-12 hs, 35% 12-18 hs, 22% 18-24 hs). Contrary to this pattern, guanacos used forests equally during the whole day for grazing and shelter (26% 0-6 hs, 28% 6-12 hs, 23% 12-18, 23% 18-24 hs) while cattle increased the forest use during daylight for grazing (8% 0-6 hs, 38% 6-12 hs, 31% 12-18, 23% 18-24 hs). Spatial overlap and habitat selection by coexisting cattle and guanacos during summer was observed in Tierra del Fuego. Cattle displaced most of guanaco natural populations probably due to competition for food during the short growth season, however, guanacos are not fully displaced from the managed area. So, co-existence of both species can be possible by combining economic and conservation purposes in the management plans. This research brings outputs to improve silvopastoral proposals at ranch and landscape level.