CLIMATE CHANGE EFFECTS ON PREDATOR/ PREY INTERACTIONS: How can we conserve persistence and resilience in a murky sea of idiosyncrasy?

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1 CLIMATE CHANGE EFFECTS ON PREDATOR/ PREY INTERACTIONS: How can we conserve persistence and resilience in a murky sea of idiosyncrasy?

2 Global climate change What is changing? Can we relate GLOBAL change patterns to LOCAL systems? Landscape variables measured at broad scale animals usually measured at local scale Everything is connected so at some point Natural Selection should elicit a response in everything.

3 Mean monthly minimum temperature: Yosemite Valley, CA Loss of 3 freezing months (Nov, Mar, Apr) Moritz et al. 2008; Western regional climate center Leading to: Higher variability in annual snowpack Earlier snow melt Decreased stream flows

4 Research on effects of climate change Models worldwide attempt to model animal distributions on predicted habitat maps Predictions: 1. Few species go extinct a. unsuitable conditions for persistence b. out competed by invading/pioneering species 2. Many species will dramatically contract in distribution a. increased fragmentation b. reduced resilience in population dynamics (more vulnerable to extinction with perturbations) 3. Others will extend their range a. usually at the expense of another species (e.g. the alpine chipmunk being displaced by lodgepole chipmunk) Community composition is going to change

5 Animals adapt on a species level Summary of Grinnell resampling small mammal survey (Moritz et al. 2008) Range Expansion Range Contraction No Change Number of species 3 spp Higher 2 spp Lower 6 spp Higher 1 spp Lower 12 spp 1 spp Both 2 spp Both No pattern or mechanism as to who s range contracted or expanded Each small mammal guild is represented in all categories ALL of these species are important prey items in the Sierra Nevada

6 Conflicting results in Sierra Nevada Within Genus (Neotoma spp.; Moritz et al. 2008) Large-eared woodrat showed no change in distribution from 1920 to 2005 Bushy-tailed woodrat showed significant change Within Species (bushy-tailed woodrat) One study showed range expansion (East slope: McDonald and Brown 1992) Another study showed range contraction (West slope: Moritz et al. 2008)

7 Idiosyncrasy in our thinking and our data Conflicting paradigms 1. Ambient temperature and animal physiological constraints influence species susceptibility to extinction (McDonald and Brown 1992) True for species constrained in distribution, e.g. high montane mammals 2. Animal distributions influenced by habitat changes not physiological constraints (Johnston and Schmitz 1997, Moritz et al. 2008) Habitat quality directly linked to population dynamics for herbivores, aka PREY Prey population dynamics highly correlated to predator population dynamics

8 Classic predator-prey population cycles: snowshoe hare and Canada lynx Trapping records from Hudson Bay, Canada Highly correlated connections in the predator-prey system - If something happens to one, it throws off the other - amplitude variability is positively related to probability of extinction

9 Prey population cyclicity Cyclicity = amplitude and frequency of cycles Increases with latitude and snow cover. Decreases with generalist predators Increases with specialist predators Prey food source reliability related to prey cyclicity (e.g. acorn crops cycle)

10 Spotted owl prey annual abundance patterns flying squirrel deer mouse Prey abundance Rosenberg et al Year

11 Prey abundance and owl reproductive success Prey abundance flying squirrel deer mouse spotted owl reproduction # of owlets / owl pair 0 Rosenberg et al Year 0.0

12 northern goshawk barred owl (invader) great horned owl raven Spotted owl Habitat and diet SPECIALISTS passerine birds shrews bats flying squirrel deer mice chipmunks seeds grasses woodrats forbs voles pollen beetles moths insects lichen fungi trees detritus shrubs leaves

13 Spotted Owl Diets: Yosemite Woodrat = also important prey species Flying squirrels Woodrats Closed canopy Open canopy

14 Flying squirrel response to climate change: 1. If forest dries out, flying squirrels follow truffles confined to riparian areas due to their prey s (truffles) association with high soil moisture 2. Predators of flying squirrels follow prey to riparian areas 3. Connectivity to prey refuge areas, high prey abundance areas, and predator refuge areas - Will they cross non-habitat patches? 4. Will predator survival decline?

15 How does idiosyncratic prey response affect the predator? All woodrats equally preferred prey Predator (spotted owls) inhabitat a gradient of particular habitat structure (e.g., late seral forest) Owls in one habitat (100 85% canopy closure) may have declining woodrats (species that prefer closed canopy) while owls in another habitat (70 60 % closure) see little change in woodrats (those that prefer open forest). Bushytailed woodrat Big-eared woodrat

16 How can we manage for spatial idiosyncrasy? Prey and Predators need access to a mosaic of habitat types habitat patches need to contain desired structure Must be connectivity between patches Many species may not cross what they perceive as non-habitat despite the size of the nonhabitat patch Conservation areas may need to expand or reassess their borders to meet these habitat shifts

17 ADAPTIVE RESEARCH WORK TOGETHER With no clear patterns of biological responses to climate change Apply general framework for approaching research Change focus as new information arises Integrate different sciences may be important in obtaining the answers we need to guide adaptive management policies

18 Adaptive Research Framework 1. Prioritize species of concern (e.g., Ecology) a. Pika are habitat specialists and they can t escape to higher ground! - vulnerable montane mammals if temperatures increase the predicted 3 0 C (McDonald and Brown 1992) b. Keystone consumer: Pika influence alpine plant composition, reduce inter-specific competition in plants c. Many predators consume pikas d. Loss of pika leads to trophic cascades

19 Adaptive Research Framework 2. Prioritize mechanisms of change affecting species (Physiology and botany) a. Pika are limited in physiological ability to deal with heat - Increased temps reduce foraging times b. Reduced snow pack change plant composition - Plant community pika not evolved to exploit? c. Lack of livestock grazing associated with higher probability of local persistence (Beever et al. 2003)

20 Adaptive Research Framework 3. Identify habitat features resilient or resistant to change (Geology) a. Rock glaciers and rock-ice features Interstitial microclimate remains cool in summer (Delaloye and Lambiel 2005) Pika refuge with disappearing snow patches (Millar et al. 2007) Rock glacier

21 Salient points? GIVE ANIMALS ROOM TO ROAM As habitat changes: Prey need to find suitable habitat and the predators need to find prey as they are seeking shifting habitats

22 Salient points? ADAPTIVE RESEARCH Integrate different sciences: knowledge diversity is important in obtaining the answers we need to guide adaptive management policies