Exploitative Competition between Mountain Hare and Moose-Qualitative Effects on Hare Winter Forage?

Simen Pedersen,Hans Chr Pedersen

doi:10.3390/ani11092638

Abstract

Simple SummaryMountain hares in Scandinavia are classified as Near Threatened in the Norwegian and Swedish Redlists assessing the risk of species extinction. This is due to a possible population decline witnessed during the last decades in Scandinavia. Competition between large herbivores such as moose, red deer, roe deer on one hand and hares on the other, is one of several hypotheses that has been put forward to explain this decline. In a cafeteria trial (providing several types of forage to determine food preference) we investigate the effects of previous moose winter foraging on the food selection (i.e., amount consumed, bites per minute and bitediameter) of downy birch and goat willow by captive hares. We find that hares do not differentiate among levels of previous moose foraging on downy birch but have larger bite diameters of goat willow earlier eaten on by moose, compared to plants not fed on by moose. Thus, effects of moose on hare winter food quality seem to be limited. We highlight the need for studies focusing on (1) effects of previous moose foraging using wild hares in a natural experimental design, and (2) effects of moose foraging on available hare food at a landscape scale during winter.Mountain hares (Lepus timidus) in Scandinavia are classified as Near Threatened in the Norwegian and Swedish Redlists. This is due to a possible population decline witnessed during the last decades in Scandinavia. Competition between large herbivores and mountain hares is one of several hypotheses that has been put forward to explain this decline. In a cafeteria trial we investigate the effects of previous moose (Alces alces) winter browsing on the food selection (i.e., biomass consumed, bites per minute and bitediameter) of downy birch (Betula pubescens) and goat willow (Salix caprea) by captive mountain hares. We find that mountain hares do not differentiate among previous browsing levels of downy birch, but have larger bite diameters of goat willow earlier browsed by moose, compared to non-browsed plants. Thus, effects of moose on mountain hare winter food quality seem to be limited. We highlight the need for studies focusing on (1) qualitative effects of moose browsing using wild mountain hares in a natural experimental design, and (2) quantitative effects of moose browsing on available mountain hare forage at a landscape scale during winter.

Highlights

In Scandinavia, mountain hares (Lepus timidus), have shown possible population declines over the past decades [1,2,3] and were classified as Near Threatened in the Norwegian Redlist in 2015 and again in 2021, as well as the Swedish Redlist in 2020
For downy birch we found no effects on amount consumed (Figure 1A), bites per minute (Figure 1B) or bite diameter (Figure 1C); mountain hares did not differentiate among level of previous browsing from moose (Table 2)
For goat willow we only found an effect of treatment on bite diameter (Figure 1C), with mountain hares having larger bite diameter for goat willow previously browsed by moose (Table 2)

Summary

Introduction

In Scandinavia, mountain hares (Lepus timidus), have shown possible population declines over the past decades [1,2,3] (www.viltdata.se accessed on: 27 August 2021) and were classified as Near Threatened in the Norwegian Redlist in 2015 and again in 2021 (www.artsdatabanken.no accessed on: 27 August 2021), as well as the Swedish Redlist in 2020 (www.artfakta.se accessed on: 27 August 2021). Color mismatch and increased predation is currently a topic of general research interest, and we have earlier shown that abundance of mountain hares is negatively affected by an interaction between reduced snow cover duration and abundance of generalist predators; red fox (Vulpes vulpes) and pine marten (Martes martes) [1]. The mountain hare may be negatively affected by top-down effects, and bottom-up through interactions with other species from within the herbivore guild [4]. In areas of high density, moose may be an important competitor towards mountain hares [8]

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