Seasonal variation in diet composition and similarity of sympatric red deer Cervus elaphus and roe deer Capreolus capreolus

Abstract

Use of food resources by herbivores depends on intrinsic constraints, essentially body size and morpho-physiological characteristics, which determine the range of foods they tolerate and environmental constraints, such as seasonality and interspecific interactions, which determine the availability of resources. We analysed a collection of rumen contents samples from sympatric populations of red deer Cervus elaphus and roe deer Capreolus capreolus and tested several theoretical predictions relating to the impact of intrinsic and environmental constraints on diet composition, diversity and similarity. Red deer consumed more slowly digestible, fibrous forage than roe deer and had a more diverse diet throughout the year, which supports predictions deriving from specific body size and morpho-physiological characteristics. In conformity with the optimal foraging theory, both species consumed more slowly digestible forage in times of low food availability (i.e. during winter) than during the rest of the year. An increase in diet similarity in winter, along with predictions from the theory on competitive interaction processes, led us to assume that food resources were not limiting and that exploitative competition between red and roe deer was unlikely in our study area. We underline the importance of studies of the use of food resources by sympatric herbivores in answering applied ecological questions at the local scale, and we suggest that the Euclidean geometrical approach we used is particularly well suited for the analysis of resource matrices, a common end-product of long-term field data gathering on the feeding habits of animals.

High red deer density depresses body mass of roe deer fawns

“…This corresponds to the Jarman-Bell principle developed to explain the coexistence among African ungulates by a partitioning of food resources that differ in fibre content (Perez-Barberia et al 2008). Therefore, while an intermediate feeder (sensu Hofmann 1989) of large size can consume both highly calorific and poor-quality food, a small-sized concentrate selector (sensu Hofmann 1989) only consumes highly digestible forage (Storms et al 2008;van Soest 1996). As a consequence, large ungulates may utilize a wider range of habitat types (du Toit and Owen-Smith 1989), whereas small herbivores tend to be more selective (Owen-Smith 2002).…”

Autumn-winter diet overlap of fallow, red, and roe deer in forest ecosystems, Southern Poland

“…They were then analysed using the "pointframe" method [47], which involved mixing them with water and smearing the samples on a tray with a grid of lines forming 100 intersection points along the bottom, allowing for random selection of 100 particles of food. The procedure was repeated three times to obtain a sample of 300 items, which is considered adequately representative [48]. Collected particles were identified Diets of analyzed species of animals were compared in terms of: 1) number of types of food; 2) breadth of food-niche (diet diversity); 3) similarities of sample contents and principal food types that samples differed by; 4) percentage of dry biomass of each type of food; 5) significance of each type of food in the diet; and 6) overlapping of the species' diets.…”

“…A change in diet can be caused not only by lack of access to certain food types in given seasons, but also to a change in the nutritive properties of the same plants over different seasons [41]. Both of these factors can cause the overlap of food-niches between cervids to be higher in winter than in other seasons [48,62]. Particular climatic conditions may cause food competition between fallow deer and indigenous cervids [62], especially in a situation when populations are too high or winter lasts longer than usual.…”

“…In order for exploitation competition to take place, an overlap in habitat use and in diet must occur simultaneously and the shared dietary resource must be limited [e.g. 48,64,65].…”

The Influence of Body Size on the Ecology of Coastal Fish Predators in The Bahamas

“…Ecological studies that examine how body size affects resource use have focused on variation among species and the resulting implications (Blackburn et al 1996, Robertson 1998, Cromsigt & Olff 2006, Bumrungsri et al 2007, Langkilde & Shine 2007, Storms et al 2008). Yet, effects of body size on resource use variation within species can also influence important aspects of population dynamics and community structure .…”