Managing urban and rural rights-of-way as potential habitats for grassland birds

Abstract

ABSTRACT. Urban grassy rights-of-way (ROWs) such as along transmission lines could be managed cumulatively as collections of potential grassland habitats to contribute to the conservation of grassland birds. To optimize conservation opportunities, managing urban ROWs for grassland birds may require reductions in frequent mowing and spraying and may also depend on the suitability of landscape structure within the urban environment. We compared effects of mowing regime relative to effects of the matrix surrounding ROWs on grassland bird abundance and occupancy along 48 ROWs in and surrounding Winnipeg, Manitoba, in 2007-2009. We used both hierarchical distance-sampling and multiseason occupancy modeling methods to account for effects of urbanization (e.g., traffic noise), observer experience, time of season, and survey time in the morning on the probability of detecting birds at study sites. We did not find differences in detection of grassland birds due to urbanization, but we did find effects of time of season, survey time in the morning, and observer experience. After accounting for availability, we found that several species declined along ROWs that were surrounded by more urban or wooded land. Western Meadowlark occupancy increased as the amount of grassland within 100 m of ROWs increased. Savannah Sparrow showed some evidence of increasing with mowing, whereas Clay-colored Sparrow showed some evidence of decreasing with mowing, although these species and Western Meadowlark also increased within hayed ROWs. We conclude that urban ROWs managed as grassland bird habitats will probably attract more individuals and species if there is less nearby urban or wooded land and more grassland, and within which there is a mixture of unmowed and hayed ROW sections. Aménagement d'emprises en milieu urbain et rural comme habitat potentiel d'oiseaux champêtresRÉSUMÉ. Les emprises herbeuses en milieu urbain, telles que celles des lignes de transport d'électricité, pourraient être cumulativement aménagées en un ensemble de milieux de prairie potentiels afin de contribuer à la conservation des oiseaux champêtres. En vue d'optimiser les occasions de conservation, l'aménagement des emprises urbaines pour ces oiseaux pourrait nécessiter une diminution de la fréquence du fauchage et de l'épandage, et pourrait aussi dépendre du caractère propice de la structure de paysage dans l'environnement urbain. Nous avons comparé les effets du régime de fauchage en fonction des effets de la matrice environnant les emprises sur l'occurrence et l'abondance d'oiseaux champêtres le long de 48 emprises situées à Winnipeg et ses environs, au Manitoba, en 2007Manitoba, en -2009. Afin de prendre en compte les effets de l'urbanisation (p. ex. bruit de la circulation), de l'expérience de l'observateur, du moment dans la saison et de l'heure de l'inventaire sur la probabilité de détecter les oiseaux aux sites d'étude, nous avons utilisé deux méthodes de modélisation : à partir de l'échantillonnage par distance hiérarchique et de la présence multisaisonn...

The effects of management practices on grassland birds—LeConte’s Sparrow (<i>Ammospiza leconteii</i>)

“…In Manitoba tallgrass prairies, LeConte's Sparrows relative abundance was higher in large tallgrass prairie patches with higher percentages of grassland and agricultural land cover in the adjacent matrix than in small patches with higher percentages of forest, wetland, and urban land cover in the adjacent matrix (Bruinsma, 2012). In another Manitoba study, LeConte's Sparrow occupancy in rights-of-way declined as the amount of urban land within 100 m of rightsof-way increased; occupancy was not related to amount of wooded land, cropland, or grassland within 100 m of rightsof-way (Leston and Koper, 2017). In tallgrass and mixedgrass prairie fragments in western Minnesota and eastern North Dakota and South Dakota, LeConte's Sparrow occupancy was higher in prairie remnants characterized by sparse vegetation and little open water, and embedded in landscapes with high matrix contagion (that is, a measure of the configuration of the different landscape element patches within the landscape) and more CRP edges (Shahan and others, 2017).…”

“…Hayfields mowed at longer than 1-year intervals provided stands of introduced, broad-leaved grasses attractive to LeConte's Sparrows. In Manitoba rights-of-way, LeConte's Sparrow occupancy was not related to any of the management treatments used to maintain rights-of-way, which were mowing and herbicide spraying once or twice per year without haying, mowing and haying once per year, or no mowing except for tree removal (Leston and Koper, 2017). In North Dakota, highest abundances of LeConte's Sparrows occurred on hayland that had been mowed 1 year previously, providing tall grass growth that was preferred for nesting (Kantrud, 1981).…”

“…In Manitoba tallgrass prairies, LeConte's Sparrow abundance was positively associated with grasslands with greater litter depth and shorter vegetation, surrounded by other grasslands (Mozel, 2010). In another Manitoba study, LeConte's Sparrow occupancy in rights-of-way (strips of grassland at least 30 meters [m] wide planted under power transmission lines) increased with increasing percentage grass cover (Leston and Koper, 2017). In mixed-grass prairies in North Dakota, LeConte's Sparrows were present in grasslands with higher percentage cover of smooth brome, quackgrass (Elymus repens), and tame legumes; lower percentage cover of native grasses and forbs; higher maximum vegetation height; and greater litter depth than in unoccupied grasslands (Grant and others, 2004).…”

“…Delaying mowing of hayfields until after July 15 or until after most nests have fledged young may protect many nests from destruction (Dale and others, 1997). In Manitoba, Leston and Koper (2017) suggested that unmowed urban grassy rights-of-way might benefit the LeConte's Sparrow. Mowing or grazing of CRP land during extremely wet years may negatively affect breeding LeConte's Sparrows because this species may only breed in this habitat under moist conditions (Igl and Johnson, 1995).…”

The effects of management practices on grassland birds — An introduction to North American grasslands and the practices used to manage grasslands and grassland birds

“…Road and transmission line rights-of-ways may provide remnant strips of grassland of varying vegetation structure that some birds may use for nesting (Camp and Best, 1994;Leston and Koper, 2017). In eastern North America, where native grassland habitats have diminished greatly in size, airport grasslands may serve as refugia for some grassland birds (Caccamise and others, 1996).…”