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Cattle versus Endangered Kangaroo Rats - PowerPoint PPT Presentation


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Cattle versus Endangered Kangaroo Rats Laura Prugh and Justin Brashares University of California Berkeley Background • Largest remnant of San Joaquin grassland ecosystem (810 km 2 ) • Key area in many T & E species recovery plans John Roser Alison Cleary Background

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Presentation Transcript
slide1

Cattle versus Endangered Kangaroo Rats

Laura Prugh and Justin Brashares

University of California Berkeley

slide2

Background

• Largest remnant of San Joaquin grassland ecosystem (810 km2)

• Key area in many T & E species recovery plans

John Roser

Alison Cleary

slide3

Background

Exotic grasses are a major problem

slide6

John Roser

Foraging

Red

Brome

slide7

1. Do GKR promote or control exotic grasses?

Soil disturbance may exotics, foraging may

Key Questions

2. Do cattle help or hurt GKR populations?

Keep habitat open, but may compete for food

3. How do GKR and cattle affect other species?

How to manage for endangered species that eat each other or compete for resources

slide8

Study Design

Control (grazed) plot

Cattle exclosure

60 m

140 m

Buffer zone around trapping grid

Rodent exclosure

Control plant sampling area

Trapping grid

slide9

Study Design

grazed

ungrazed

slide11

Plant Surveys

John Chestnut

slide12

GKR Surveys

3 sessions, 6,615 captures, 1,098 individuals

slide13

Antelope Squirrel Surveys

2 sessions, 440 captures, 131 individuals

slide15

Food Choice Trials

12 seed piles per trial, n = 30 trials (1 per plot)

slide17

PRELIMINARY

RESULTS

John Roser

slide18

1. Do GKR promote or control exotic grasses?

Soil disturbance may exotics, foraging may

Key Questions

• Exotic plant cover on and off GKR precincts

• GKR diet preferences

slide21

Erodium circutarum (filaree)

exotic plant, everywhere

slide22

Amsinckia tessellata

native plant, mainly on precincts

slide24

GKR Diet Choice vs. Composition

Filaree

r = -0.38

Plant composition tends to be negatively correlated with diet choice of local GKR (Sign test, P = 0.047)

slide25

Key Questions

1. Do GKR promote or control exotic grasses?

Soil disturbance exotics and some natives

Preference for some exotics may limit their abundance

slide26

Key Questions

2. Do cattle help or hurt GKR populations?

slide28

Key Questions

3. How do GKR and cattle affect other species?

How to manage for endangered species that eat each other or compete for resources

slide30

Keystone Role of GKR

John Roser

John Chestnut

John Roser

slide31

Conclusions

• Giant kangaroo rats have strong, and potentially opposing, influences on plants

- disturbance promotes, foraging controls exotics

• Giant kangaroo rats are keystone species

- precincts benefit squirrels and reptiles

• Grazing effects will take time to emerge

- may benefit species by reducing cover, but may also compete for forage

slide32

Acknowledgements

Bureau of Land Management: Larry Saslaw, Kathy Sharum, Johna Hurl

CDF&G: Bob Stafford, Deborah Hillyard

TNC: Tom Maloney, Scott Butterfield

Funding & Support: USFWS, TNC, BLM, UC Berkeley

Field Assistants and Students: J. Roser, J. Chestnut, N. Petersen, C. Daman, N. Raubitschek, T. Bean, J. Castillo, P. Elsen, R. Wenk, G. Butterworth, L. Navarette, B. Olney, J. Miller, A. Cleary, K. Chu, A. Bruys, B. Berube, N. Tuttle, and M. Vance

slide33

Questions?

Alison Cleary