Graduate Thesis Or Dissertation
 

Relationship between habitat changes and productivity of sage grouse at Hart Mountain National Antelope Refuge, Oregon

Public Deposited

Downloadable Content

Download PDF
https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/rv042z340

Descriptions

Attribute NameValues
Creator
Abstract
  • From 1987-1997, Oregon State University conducted studies at Hart Mountain National Antelope Refuge (HMNAR) to better understand the relationship between grouse productivity and key habitat components. Early studies indicated sage grouse habitat preference and reproductive success were related to particular forbs (including legumes and milky juice composites) and structural characters of native bunchgrasses. After early studies (1989-1991), climatic conditions and land-use practices changed at HMNAR. Livestock grazing was eliminated from HIVINAR in 1991 and during 1989-1997 there was an upward trend in crop year precipitation (total precipitation from 1 September - 30 June). Because of these changes a study was initiated to test the relationships inferred from earlier studies. Two sample periods (1989-1991 and 1995-1997) were compared to determine the collective effect of increased crop year precipitation and reduced livestock grazing on key habitat components in 4 cover types and on sage grouse productivity measures. Habitat sampling during 1995-1997 indicated that spring and summer forb cover and residual grass cover increased in most cover types compared with 1989-1991. During the earlier studies at Hart Mountain, 65% of radio-marked hens initiated nests, 22% of nesting hens were successful, and 33% of successfully nesting hens recruited chicks into the 1 August population. During 1995-1997, 99% of radio-marked hens initiated nests, 37% of nesting hens were successful, and 39% of successfully nesting hens recruited chicks into the 1 August population. Increased nest initiation rates during 1995-1997 compared with 1989-1991 were concordant with increases in spring forb cover. Greater availability of spring forbs at Hart Mountain probably provided hens more opportunity to become physiologically prepared to attempt nesting. Nest success was greater during 1995-1997 compared with 1989-1991. Corresponding increases in nest success and residual grass cover were probably a result of a higher probability of hens initiating nests in cover that provided enhanced nest concealment. Brood success and summer forb availability were greater during 1995-1997 compared with 1989-1991. Increased forb availability probably allowed hens to remain in upland brood-rearing habitats longer (thereby providing a greater dispersion of broods) and reduced movements by hens with broods, which resulted in increased chick survival. This study confirmed the importance of spring forbs, residual bunchgrass, and summer forbs to sage grouse productivity, on a landscape scale and grouse population basis. I concluded these habitat components are key to sage grouse reproductive success.
Resource Type
Date Available
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Committee Member
Non-Academic Affiliation
Subject
Rights Statement
Publisher
Language
Digitization Specifications
  • Master files scanned at 600 ppi (256 Grayscale) using Capture Perfect 3.0 on a Canon DR-9080C in TIF format. PDF derivative scanned at 300 ppi (256 B&W), using Capture Perfect 3.0, on a Canon DR-9080C. CVista PdfCompressor 3.1 was used for pdf compression and textual OCR.
Replaces

Relationships

Parents:

This work has no parents.

In Collection:

Items

Thumbnail Title Date Uploaded Visibility Actions
file details Coggins_Kreg_A_1998_ocr.pdf 2017-10-23 Public Download