Factors Affecting Diet Variation in the Pyrenean Rock Ptarmigan (Lagopus muta pyrenaica): Conservation Implications

Abstract

The Pyrenean rock ptarmigan (Lagopus muta pyrenaica) lives at one of the southernmost limits of the ptarmigan range. Their small population sizes and the impacts of global changes are limiting factors in the conservation of this threatened subspecies. An effective conservation policy requires precise basic knowledge of a species' food and habitat requirements, information that is practically non-existent for this Pyrenean population. Here, we describe the diet of a ptarmigan population in the Eastern Pyrenees, the environmental factors influencing its variability and the relationship between diet floristic composition and quality. Diet composition was determined by microhistological analysis of faeces and diet quality was estimated from free-urate faecal N content. Our results show that grouse diet is based mainly on arctic-alpine shrubs of the Ericaceae family, as well as dwarf willows (Salix spp.) and Dryas octopetala. The most frequently consumed plant species was Rhododendron ferrugineum, but its abundance in the diet was negatively related to the diet nitrogen content. Conversely, the abundance of Salix spp., grass leaves and arthropods increased the nitrogen content of the diet. Seasonality associated with snow-melting contributed the most to variability in the Pyrenean ptarmigan diet, differentiating winter from spring/summer diets. The latter was characterised by a high consumption of dwarf willows, flowers, arthropods and tender forb leaves. Geographic area and sex-age class influenced diet variability to a lesser extent. Current temperature increases in the Pyrenees due to global warming may reduce the persistence and surface area of snow-packs where preferred plants for rock ptarmigan usually grow, thus reducing food availability. The high consumption of Rh. ferrugineum characterised the diet of the Pyrenean population. Given the toxicity of this plant for most herbivores, its potential negative effect on Pyrenean ptarmigan populations should be evaluated.

Influence of Snowmelt Timing on the Diet Quality of Pyrenean Rock Ptarmigan (Lagopus muta pyrenaica): Implications for Reproductive Success

“…Faecal samples of young were identified by their size. Seasonally, 81 samples (67%) were collected during the spring/summer post-melting period, when the main diet variation took place, and 40 samples (33%) were collected in the autumn/winter period [ 30 ]. A total of 121 droppings were collected and analysed by means of microhistological analysis to determine diet composition [ 35 ].…”

“…Relying on previous studies of relationships between climate and reproduction, and a detailed description of food habits of a rock ptarmigan population in the Pyrenees [ 15 , 30 ], we present a possible mechanism to explain the mediating role of food quality in the reproductive success of the Pyrenean rock ptarmigan. Specifically, we aim to show that nitrogen content of woody plants (the main food component of grouse diet at the beginning of the growing season) varies depending on the phenological stage (or phenophase), which in turn is closely linked to snowmelt date.…”

Getting the dietary knowledge to restore a missing species: seasonal diet of Atlas deer Cervus elaphus barbarus in Tazekka National Park, Morocco

“…Only fresh faeces were collected (Malan et al 2012, Zweifel-Schielly et al 2012, Bezard et al 2015, Ferretti et al 2015, Ben Mimoun and Nouira 2016, García-González et al 2016) because this is important for assessing temporal diet changes (García-González et al 2016). The age of faeces was determined from smell, humidity and presence of mucus (Bezard et al 2015).…”

“…To prevent mould and epidermis alteration in faeces, two procedures are possible: oven drying (at 60°C for 48 h or longer if faeces are bulky) and freezing. Mysterud and Austrheim (2016) García-González et al (2016) have stored the droppings in acetoacetic formalin until analysis. For each sample, we noted useful information such as number, contact information, date, time and type of environment.…”

“…To quantify consumed species found in faeces and calculate their relative abundance, we divided the number of identified fragments of each species by the total number of identified fragments multiplied by 100 (Shah et al 2009, Ligi and Randveer 2012, García-González et al 2016.…”