Nesting Success of Grassland Birds in Fragmented and Unfragmented Landscapes of North Central South Dakota

Decline of grassland bird species has frequently been linked to habitat loss and fragmentation. A large amount of remaining native prairie is in the form of grazed pastureland; however, few studies have focused on assessing pastureland as habitat. While studies have found that species occurrence, density and breeding success is higher in large, unbroken habitat patches, the surrounding landscape likely plays an important part in habitat quality. The main objective of this study was to assess the nesting success of grassland birds in relation to habitat patch size and the composition of the surrounding landscape. I evaluated nesting success in moderately grazed native pastures in north central South Dakota within the following categories: 1) small patch area (<50 ha) surrounded by <40% grassland; 2) small patch area (<50 ha) surrounded by >50% grassland; 3) large patch area (>100 ha) surrounded by <40% grassland; and 4) large patch area (>100 ha) surrounded by >50% grassland. I used the nest survival model in program MARK to determine nest survival probabilities as a function of vegetation, patch and landscape variables. I also used logistic regression to construct models to evaluate the influence of vegetation, patch and landscape variables on the likelihood of nest parasitism. The most common species found were the chestnut-collared longspur (Calcarius ornotus ); western meadowlark (Sturnella neglecta); grasshopper sparrow (Ammodramus savannarum); savannah sparrow (Passerculus sandwichensis); ringnecked pheasant (Phasianus colchicus); and dabbling ducks (Anas spp.). Response to landscape and patch variables varied among species. Larger patches were positively correlated with daily survival of chestnut-collared longspur and dabbling duck nests. Parasitism rates of savannah and grasshopper nests also decreased in large patches compared to small. Nest success rates for western meadowlarks were highest in small patches surrounded by high percent grass. Daily nest survival rates for western meadowlarks, savannah sparrows and grasshopper sparrows were higher in landscapes with >50% grassland habitat. Management recommendations include continued research into the effects of fragmentation on nesting success and also on predator activity, preservation of large, unbroken tracts of native prairie, and, where large tracts are unavailable, preservation of smaller prairie patches, especially those in high-percentage grass landscapes.

Name thesis:degree_name

Master of Science (MS)

Level thesis:degree_level

Thesis - University Access Only

Discipline thesis:degree_discipline

Wildlife and Fisheries Science

Year

2007

Author dc:creator

• Berman, Gillian M.

Contributors dc:contributor

• Ken Higgens

• Natural Resources and Conservation

Statement dc:rights

• Copyright 1989 Gillian M. Berman. All Rights Reserved.

Language dc:language

en

Repository record dc:identifier

https://openprairie.sdstate.edu/etd/292

OAI identifier oai:identifier

oai:openprairie.sdstate.edu:etd-1292