The number of pores per area of eggshells is not always a reliable indicator of Rheidae species

From the end of the Pleistocene and up until the late Holocene, bones and abun- dant eggshell fragments testify to the hunting by the indigenous people of Rheidae in the Pampas and Chaco regions (greater rhea, Rhea americana), and in the Argentinian Patagonia (lesser/ Darwin´s rhea, R.pennata). The traditional method to set apart eggshell fragments from these two species consisted in counting the number pores on a given area to estimate their density. In this paper we evaluate the validity of this method with a new protocol to facilitate counting and assess its reliability on a large eggshell sample. As has been repeatedly proved, the greater rhea has a larger pore density than the lesser rhea. However, the variability of this density within each species, and even within the same egg, needs to be considered as this may lead to erroneous identification. More so when the number of pores per cm2 falls in the lowest range of the greater rhea or the highest range of the lesser rhea. In general, it is easier to misidentify a greater rheaeggshell fragment for that of the lesser rhea than the other way around. The possibility of misidentification also depends on the area of the shell that is being analyzed, since the original method did not apparently assess the density of pores in different areas of the same egg for each species. Although our results indicate that identification based on the original method is not as reliable as the one we propose here, a reappraisal of it with larger samples deriving from a larger specter of populations from both species would be recommendable.

Analysis of the spatial variation in the abundance of lesser rheas using density surface models

Context The study of the spatial variation in abundance of wild populations and the identification of factors explaining the observed patterns are key both to understand aspects of basic ecology and the effects of human activities. This is usually difficult to evaluate for low-density and widely distributed species, such as the lesser rhea (Rhea pennata pennata), an endemic bird from South America. Recent advances in spatial modelling such as the density surface models (DSM) combine distance-sampling procedures with modelling techniques to produce maps of spatial variation in abundance, and its relationship with predictive variables. Aims We aimed to analyse the spatial distribution and abundance of lesser rhea, and the variables that affect its abundance in Península Valdés (PV) Argentine Patagonia. Methods We conducted 338.4 km of ground surveys of lesser rheas in PV during the end of the Austral summer of 2015. Spatial models were constructed using DSM. Ecological and human-related variables were included in the models to account for variation in the abundance of animals at 4-km2 spatial resolution. Key results We estimated an overall density of 0.44 birds km–2 (CV = 32%) for the prediction area of 3320 km2. High values of normalised difference vegetation index, a correlate of plant productivity, were associated with increased numbers of lesser rheas. The location of ranch buildings, indicators of human presence, had a strong negative effect on lesser rheas, although their abundance increased at high sheep stocking rates. Conclusions As reported by previous studies in different sites, the abundance of lesser rheas in our study area was low. The use of DSM allowed a detailed examination of the spatial variation, as well as the variables involved and the uncertainty of the prediction. Implications The use of DSM techniques can be a useful tool for conservation planning and monitoring. Spatial, high-resolution data combined with knowledge on the factors affecting the number of animals are crucial to target specific conservation actions and monitor their results, and should allow government agencies to make better decisions concerning conservation-oriented management.

A new species ofProcyrnea(Nematoda: Habronematidae) parasitic inRhea pennata(Aves: Rheidae) from Patagonia, Argentina, with a key to species of the genus

Procyrnea choiquen. sp. is described from the lesser rhea,Rhea pennatad´Orbigny (Aves: Rheidae), from the Protected Natural Area Península Valdés, Chubut province, Argentina. The new species resemblesP. ficheuri,P. murrayi,P. excisiformis,P. dollfusi,P. haliasturi,P. anterovulvata,P. graculae,P. brevicaudata,P. uncinipenis,P. javaensis,P. ameerae,P. ornata,P. aegotheles,P. spiralis,P. ruschiiandP. aptera, mainly in the absence of lateral alae; but differs from its congeners by having a left spicule without barbs, the position of the vulva which is post-equatorial, the absence of lateral ridges, absent median precloacal papilla, asymmetrical caudal alae, males more than 6 mm long, left spicule 1 mm long and spicule ratio 1:3. Our results extend the taxonomy ofProcyrneaChabaud, 1958 and comprise the first report of a habronematid fromR. pennata.A key to species ofProcyrneais presented.

The ecological role of native and introduced species in the diet of the puma Puma concolor in southern Patagonia

There is evidence for the ecological extinction of the native prey of the puma Puma concolor in north-western Argentine Patagonia. In this study we examine whether this is also the case in southern Patagonia. From 2004 to 2007 we examined the puma’s diet in three protected areas and two sheep ranches in Santa Cruz province. A total of 282 puma scats were analysed. In two of the protected areas and in the ranches 60–74% of the puma’s diet was native prey. Prey species were primarily guanaco Lama guanicoe, followed by Patagonian mara Dolichotis patagonum, lesser rhea Pterocnemia pennata pennata, Patagonian pichi Zaedyus pichiy and Magellanic penguin Spheniscus magellanicus. In the third protected area the main prey was the European hare Lepus europaeus. Our results show a clear difference in the diet of the puma in southern compared to north-western Patagonia. Large native herbivores (i.e. guanaco and lesser rhea) maintain their role as the main prey species for the puma in southern Patagonia. We suggest, therefore, that native prey could be restored to those areas of Argentine Patagonia, such as the north-west, where they are currently ecologically extinct. Facilitating native species recovery and/or restoration and applying more rigorous controls to prevent the introduction of potential alien prey species of the puma both, within and outside protected areas, needs to be evaluated as a regional strategy.