Fernando R. Barri

Habitat selection by reintroduced guanacos (Lama guanicoe) in a heterogeneous mountain rangeland of central Argentina

Quebrada del Condorito National Park is located in the upper belt of the mountains of central Argentina and preserves a heterogeneous rangeland area. After the creation of the National Park, in 1996, domestic livestock were gradually removed to avoid soil loss and degradation due to overgrazing in this fragile ecosystem. Lack of large-scale herbivory allowed the expansion of tussock grasslands over grazing lawns. In 2007 a guanaco (Lama guanicoe) population was reintroduced; this large native herbivore, that had become extinct in the region was selected, because it is a low-impact grazer. Habitat selection by the guanaco population reintroduced to the National Park was studied. Seven habitat types previously defined for the region were considered, each one exhibiting a particular dominant plant growth form and different per cent cover of plant species. Guanacos made a positive selection of moist and dry grazing lawns, and avoided tussock grasslands and forests. The reintroduced guanacos selected landscapes with short plants and a high percentage of perennial graminoids and forbs, which are guanacos’ preferred food items. The results indicate that availability of forage of a nutritive value and dominant plant growth form largely explain habitat selection by guanaco in the National Park; this information can be useful for both the ongoing guanaco reintroduction project and the design of management strategies aimed at ecological restoration of this important rangeland region of central Argentina.

Effects of hunting, egg harvest and livestock grazing intensities on density and reproductive success of lesser rhea Rhea pennata pennata in Patagonia: implications for conservation

Wild lesser rheas were studied during two re- productive seasons (2004-2005 and 2005-2006) in three adjacent ranches in Argentine Patagonia. These ranches differed in hunting pressure and egg harvest (protected, moderate and intensive use of the species), and livestock grazing conditions (with and without overgrazing). Density of individuals and nests, clutch size, brood size, hatching success, chick survival and recruitment rate were estimated in each area. At the ranch with intense hunting pressure, egg harvesting and livestock grazing, density of lesser rheas was the lowest and reproductive events were not recorded. None of the recorded demographic parameters differed signifi- cantly between the ranch where the species is protected and there is low livestock grazing intensity and the ranch where there is moderate use of the species and intensive grazing. Our work suggests that intense hunting and egg harvesting would have stronger effects than overgrazing on the density and reproductive success of wild lesser rhea populations in

Physical characteristics and chemical composition of Lesser Rhea (Pterocnemia pennata) eggs from farmed populations

1. Eggs from 4 farmed populations of Lesser Rhea (Pterocnemia pennata) were studied to determine their physical and chemical characteristics. 2. None of the physical variables (weight of whole egg, yolk, albumen and shell; proportion of yolk based on egg content; proportion of shell based on entire egg weight; volume; density) showed significant differences between populations. 3. Among chemical variables, moisture, both saturated fatty acids (palmitic 16 : 0 and stearic 18 : 0), one monounsaturated fatty acid (palmitoleic 16:1), and one polyunsaturated fatty acid (arachidonic 20 : 4), did not differ between populations, whereas other variables (protein, lipid and ash contents; fatty acids: oleic 18 : 1, linoleic 18 : 2, linolenic 18 : 3; PUFA; PUFA/SFA; cholesterol) differed significantly.

Rearing Greater Rhea (Rhea americana) chicks: is adoption more effective than the artificial intensive system?

1. Survival and weight gain of farmed Greater Rhea (Rhea americana) chicks reared by the adult males that adopted them were compared with those of chicks reared under an artificial intensive system. 2. Both variables were periodically recorded up to the age of 3 months. Gompertz growth curves were fitted to individual growth data using the average adult weight of this population as asymptote. 3. No significant differences in survival rate were detected between systems (adoption = 47%, intensive = 43%). However, during the first half of the breeding season (mid-spring to mid-summer), the growth rate of adopted chicks (0·01481) was higher than that of intensively reared chicks (0·01296). 4. The adoption system may be more effective in terms of growth, and is probably more efficient in cost/effectiveness than the artificial intensive technique most frequently used. Adoption by males has additional advantages, such as a correct imprinting of the chicks and the selection of more capable individuals. Therefore, it should be used not only commercially but also in conservation projects where individuals are released to the wild.

Nest-site habitat selection by Lesser Rheas (Rhea pennata pennata) in northwestern Patagonia, Argentina

Selection of nest-site habitat by a population of wild Lesser Rheas (Rhea pennata pennata) was studied in the northwestern Patagonia steppe, Argentina, during two reproductive seasons (2004/2005 and 2005/2006). Nest spatial distribution was compared with randomly selected points in the study area. Contrary to observations in other ratite species, nest distribution showed an aggregate pattern associated with “mallín” (meadow) areas, which are habitats of higher productivity in the Patagonia steppe. Moreover, similar to observations made on the Greater Rhea (Rhea americana), vegetation cover was higher in nest sites than in randomly selected sites, probably because higher vegetation provides concealment from predators and protection from the strong westerly winds that frequent in this region. Our results reinforce the importance of “mallín” areas for the reproduction and conservation of this threatened ratite species.

Can persuasive and demonstrative messages to visitors reduce littering in river beaches

Littering of public areas is a significant problem worldwide. Here we evaluate the success of persuasive and demonstrative messages at reducing littering in highly visited river beaches in Argentina. We made an intervention at the beaches which consisted of a personalized verbal request asking visitors to take their litter to the waste cans (persuasive message) while they were exposed to the example of picking up the litter already left on the beach (demonstrative message). We conducted 102 observations distributed over 29 dates, two years and four beaches. Each observation consisted of three or four rounds: before the presence of visitors we cleaned the beaches, during the stay of visitors we made the intervention (once or twice) in two out of the four beaches, and early next morning we estimated the amount of litter left per beach. Litter weight ranged from 0 to 53gvisitor-1day-1. Littering per visitor was reduced an average of 35% due to the intervention (p=0.049). We also found differences among beaches (p=0.001), and an increase in littering with crowding (p=0.005). We show for the first time that the personalized request combined with the example of picking up litter is effective in reducing littering in a Latin American country.

Foraging and vigilance time allocation in a guanaco (Lama guanicoe) population reintroduced in Quebrada del Condorito National Park (Córdoba, Argentina)

In reintroduction projects, ethology studies play a significant role in evaluating the behaviour of the individuals in habitats where they are reintroduced. We studied foraging and vigilance time allocation of a guanaco (Lama guanicoe) population reintroduced in Quebrada del Condorito National Park (QCNP), in the central mountains of Córdoba, Argentina. On average, individuals showed a higher proportion of time invested in vigilance and a lower proportion of time invested in foraging than a previously studied guanaco population belonging to the same ecological region as the source population, suggesting that at the time of this study, the reintroduced population was not fully adapted to the new habitat or suffered from an increased predation pressure. On the other hand, as expected for the species, throughout the study period, males allocated more time to vigilance than females, both sexes increasing vigilance during the reproductive period, and females increasing foraging time allocation during the post-reproductive period. Taking into account that further reinforcement to the existing population is planned, the present results may contribute to the elaboration of management strategies aimed at the successful establishment of guanaco in QCNP.

Effects of group size, habitat and hunting risk on vigilance and foraging behaviour in the Lesser Rhea (Rhea pennata pennata)

Abstract Gregariousness is a known anti-predator strategy, but factors other than the size of groups, such as the levels of predation pressure or habitat, can affect vigilance and foraging behaviour in birds. We studied the effects of group size, habitat (shrubland steppe v. meadows), and risk of hunting by humans (protected core area v. edge area exposed to poaching) on vigilance and foraging behaviour of wild populations of the Lesser Rhea (Rhea pennata pennata), a near-threatened ratite, in north-western Patagonia, Argentina. On average, Lesser Rheas allocated 18% of their time to vigilance and 67% to foraging. Individuals tended to be more vigilant with declining group size, in areas with low visibility that hinders escape by running, and in areas exposed to hunting, than in open habitats with abundant food or sites with low risk of hunting. Although time spent foraging was also influenced by habitat type and hunting risk, there was no direct relationship between foraging time and group size. As in other species of ratite, Lesser Rheas seem to take advantage of flocking as an anti-predation strategy. Our data do not only confirm the influence of group size, but also of habitat structure and hunting risk, in determining the behaviour of this flightless bird in the wild.

Characteristics, abundance and fertility of orphan eggs of the Lesser Rhea (Pterocnemia-Rhea-pennata pennata): implications for conservation

The Lesser Rhea (Pterocnemia-Rhea-pennata pennata) has a complex reproductive system that combines polygyny with sequential polyandry, in which males build the nest, fully incubate the eggs and care for the young. As occurs with the Greater Rhea (Rhea americana), Lesser Rhea females sporadically lay eggs outside the nest (‘orphan’ eggs), which are not incubated and thus fail to hatch. We have examined the orphan eggs of Lesser Rhea over two separate breeding seasons to determine their abundance and fertility status. During 2004 and 2005, weekly ground searches for orphan eggs were conducted in a wild population of Lesser Rhea in northwestern Patagonia, Argentina. During these searches the total number of nests, eggs in each nest and orphan eggs laid outside the nests was recorded. Orphan eggs represented approximately 7% of the total eggs laid in a breeding season. Six fresh orphan eggs were artificially incubated, four of them being fertile. Orphan eggs seemed to have two origins: some were laid near deserted nests in the early to mid-reproductive season; others were probably laid by first-time breeders and were found later in the reproductive season. Given the near-threatened status of the Lesser Rhea, harvesting and artificial incubation of orphan eggs, which otherwise would be unproductive, may contribute significantly to the conservation of this species, i.e., ‘recovered’ birds could be used for reintroduction or reinforcement of wild Lesser Rhea populations.