tailed Jackrabbits in the Tahoe Basin T. Will Richardson, Ph.D. - - PowerPoint PPT Presentation

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tailed jackrabbits in the tahoe
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tailed Jackrabbits in the Tahoe Basin T. Will Richardson, Ph.D. - - PowerPoint PPT Presentation

Feb 10, 2024 17 likes •398 views

Status and Distribution of White- tailed Jackrabbits in the Tahoe Basin T. Will Richardson, Ph.D. Tahoe Institute for Natural Science Montane Lagomorphs Ignored by recent monitoring efforts at Tahoe and throughout Sierra Hold keystone

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Status and Distribution of White- tailed Jackrabbits in the Tahoe Basin

  • T. Will Richardson, Ph.D.

Tahoe Institute for Natural Science

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Montane Lagomorphs

  • Ignored by recent monitoring efforts at Tahoe

and throughout Sierra

  • Hold keystone positions in shaping both

vegetation structure and predator communities

  • Famously fecund
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Montane Lagomorphs

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Montane Lagomorphs

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Montane Lagomorphs

  • Pika (Ochotona princeps)
  • Nuttall’s Cottontail (Sylvilagus nuttallii)
  • Snowshoe Hare (Lepus americanus tahoensis)
  • Black-tailed Jackrabbit (L. townsendii)
  • White-tailed Jackrabbit (L. californicus)
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White-tailed Jackrabbits

  • Large, alpine jackrabbit
  • Prefers open habitat
  • Formerly widespread and

common

  • Pop. now fragmented and

apparently declining drastically

  • Considered extirpated from

Tahoe Basin (USFS-LTBMU, NDOW)

  • No documented Tahoe records

for decades

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White-tailed Jackrabbits

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White-tailed Jackrabbits

  • Why no records?

– High elevation – Cryptic and shy – Nocturnal – Confusion with Snowshoe Hare – Nobody’s been looking

  • Restricted to higher elevations

– “Close to or above timber line” – Mostly above 8500’

  • Potentially impacted by global climate change
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White-tailed Jackrabbits

  • Objectives

– Confirm and document persistence of species in Tahoe – Document baseline distribution – Estimate population within region – Identify habitat associations

  • Methods

– Diagnostic sign

  • Pellets
  • Tracks

– Camera trapping

  • Trailmaster (film)
  • TrophyCam (digital)

– Direct Observation

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Specimen Record

  • “Tahoe City”
  • “Edgewood”
  • “3 mi, S. Mount Rose,

8500 feet”

  • “Woodfords
  • “Hope Valley, 5270

feet”

  • Round Mound - 1927
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Sign

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Sign

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Sign

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Sign

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Sign

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Sign

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Sign

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Black-tailed Jackrabbit!

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Sign

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Complications

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Complications

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Complications

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Complications

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Complications

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Why Winter?

  • Easier to find tracks and pellets
  • Less cover = more concentrated

animals

  • Less by-catch
  • Easier backcountry travel
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Spatial and Temporal Patterns

  • Habitat associations conformed to expectations

– subalpine and alpine slopes and flat-topped ridges

  • Soil type may play a role

– very little evidence in sandy, decomposed granite

  • Dominant vegetation was consistent

– Artemisia tridentata – Leptodactylon pungens* – Holodiscus sp. – Chrysothamnos sp. – Pinus albicaulis – Juniperus occidentalis

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Spatial and Temporal Patterns

  • Greatest apparent densities associated with

largest expanses of preferred habitats

  • Animals may move downslope in winter where it

is easy to do so

  • Limits to dispersal
  • Metapopulation dynamics?
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Pellet Surveys

  • Confident Species ID w/ DNA techniques
  • Easier to randomize sampling
  • More efficient, less dependent on cooperative

weather

  • Population Estimates

– Pellet Counts – Genetic Techniques

  • Connectivity of population(s)
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DNA analysis of pellets

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Many Thanks To:

– Nevada Division of State Lands, Tahoe License Plate Grant Program – David Catalano, NDSL/NDOW – Peter Brussard, Eveline Sequin, and Dennis Murphy, UNR – Ben Sacks and Mark Statham, Veterinary Genetics Lab, UC Davis