Document Type

Thesis - Open Access

Award Date

2017

Degree Name

Master of Science (MS)

Department

Natural Resource Management

First Advisor

Joshua D. Stafford

Keywords

alfalfa, nesting ecology, nest-site selection, nest survival, thermal ecology, waterfowl management

Abstract

The northern Great Plains provide critical breeding habitat for waterfowl and gamebirds in the United States. Peak commodity prices in the late 2000s resulted in increased agricultural production and large-scale conversions of grassland habitat to monoculture row crops. However, recent declines in commodity prices have created a renewed interest for private landowners to diversify crops and enroll in government subsidized conservation programs that convert idle grassland and unproductive cropland to wildlife friendly perennial grassland plantings. Exploring alternative grassland restoration techniques can improve the efficiency of management practices to benefit future wildlife habitat and productivity on both public and private lands. We evaluated gamebird nest production in Roundup Ready© alfalfa (Medicao sative, hereafter alfalfa) used to prepare seedbeds for perennial grassland conversion. Nest productivity in alfalfa is often reduced when haying occurs during the peak nesting period. Therefore, we investigated the influence of delaying the first harvest date (July 10) on nest production by systematically nest dragging alfalfa and other typical grassland plantings found on game production areas in eastern South Dakota during the summers of 2015-2016. Additionally, the structural and thermal qualities of grassland nesting habitat that can influence nest site selection and success are poorly understood. Thus, we explored the thermal ecology of upland nesting ducks (Anatinae) using black-bulb temperature (Tbb) probes. We measured vegetation and thermal characteristics at varying relevant scales to evaluate the relative influence of habitat on nest-site selection and survival. Additionally, we compared rates of nest density and nest initiation dates to further evaluate patterns of use among different cover types. We found levels of vegetation in alfalfa to be consistently lower than in other grassland types, however, rates of nest density and nest survival in alfalfa were comparable or higher than other grassland types. Nests were consistently initiated in alfalfa fields later than other grassland types. Only 9% (n = 3) of nests in alfalfa fields were destroyed during haying and suggested that the 10 July delayed harvest date effectively minimized nest losses. Collectively, these results suggested that alfalfa provided important nesting cover for late-nesting and re-nesting grassland nesting ducks and gamebirds. Results of temperature data revealed considerable inter-field heterogeneity, as Tbb ranged as much as 35°C, when air temperatures exceeded 30°C. Ducks selected for thermally buffered nest sites with nests being as much as 3°C cooler than non-nest sites. We found that vegetation density (β = - 0.05, P ≤ 0.001), height (β = -0.04, P ≤ 0.001), and litter depth (β = -0.01, P ≤ 0.001) influenced Tbb. However, only litter depth varied between nest and non-nest sample types (F1,209 = 9.15, P = 0.003) and failed and successful nests (F1,98 = 5.7, P = 0.019), which suggested that this component played an important role in the moderation of temperatures at the nest. Additionally, we found that nest survival was positively associated with increased exposure to cold temperatures (β = 3.25, SE = 0.21). Overall, these results illustrate the importance of managing for heterogeneous grasslands and will provide land managers with information to maximize quality and available avian nesting habitat in the northern prairie.

Description

Includes bibliographical references (pages 115-122)

Format

application/pdf

Number of Pages

161

Publisher

South Dakota State University

Rights

In Copyright - Educational Use Permitted
http://rightsstatements.org/vocab/InC-EDU/1.0/

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