Abundance, territory sizes, and pairing success of male Henslow's Sparrows in restored warm- and cool-season grasslands

Abstract

Henslow's Sparrows (Ammodramus henslowii) are known to breed in restored grasslands consisting of either warm-or cool-season grasses, but additional information is needed concerning their breeding biology in these two types of grasslands. We compared the abundance, territory sizes, and pairing success of male Henslow's Sparrows in grasslands in west-central Missouri in 2010 and 2011 using a paired-treatment design, where warmand cool-season grasslands were located in close proximity. Selection indices indicated no apparent preference by male Henslow's Sparrows for either type of grassland, and the territory sizes and pairing success of males in cool-and warm-season grasslands did not differ. In addition, we found no significant differences in habitat structure between these grassland types. Thus, our results suggest that the warm-and cool-season grasslands in our study provided suitable habitat for Henslow's Sparrows. Other investigators have drawn similar conclusions for Henslow's Sparrows and for grassland birds in general, with the structural characteristics and, for some species, the size of grasslands being more important for grassland birds than plant species composition.RESUMEN. Abundancia, tamaño de territorio yéxito de emparejamiento en machos de Ammodramus henslowii en pastizales de temporada caliente y fría, restaurados Se sabe que Ammodramus henslowii se reproduce en pastizales compuestos por pastos de temporadas calientes o frías, pero se necesita información adicional sobre la biología reproductiva en estos dos tipos de pastizales. Comparamos la abundancia, tamaño de territorios yéxito de emparejamiento en machos de A. henslowii en pastizales en el oeste central de Missouri en el 2010 y 2011 usando un diseño pareado, en el cual pastizales de temporada caliente y fría fueron localizados en estrecha proximidad. Losíndices de selección no indican aparente preferencia de machos de A. henslowii por alguno de los tipos de pastizales, y no hubo diferencia en el tamaños del territorio o eléxito de emparejamiento de machos en pastizales de temporada caliente y fría. Adicionalmente, no encontramos diferencias significativas en la estructura del hábitat entre estos tipos de pastizales. Por lo tanto, nuestros resultados sugieren que pastizales de temporada caliente y fría proporcionan hábitat adecuado para A. henslowii. Otros investigadores han llegado a conclusiones similares para A. henslowii y en general para aves de pastizales, en donde características de la estructura y, para algunas especies, el tamaño del pastizal es mas importante para las aves de pastizales que las especies de plantas que lo componen.

Bird-Habitat Relationships in Restored Meadows in Southeastern Pennsylvania

“…While there are benefits to planting native species in ecological restoration, this study and others have shown higher abundance of bird species of conservation concern in non-native cool-season grasslands (Madden et al 2000, McCoy et al 2001, Davis et al 2013. Lower abundances in areas with native grasses, however, might be driven by habitat structure rather than species composition ( Jaster et al 2013); many restored meadows are planted with native warm-season grasses at high densities that preclude use by species such as eastern meadowlarks and bobolinks, obligate grassland species of conservation concern (Partners in Flight Science Committee 2012). Restoration decisions should be based on an analysis of the benefits of nonnative species to wildlife species and the costs of potential invasion or spread of non-native species to other habitats (Ewel and Putz 2004).…”

Grassland bird community response to vegetative diversity in restorations in northwestern Iowa

“…In our study, exotic cool-season grass cover and total grass cover were highly correlated (r 2 = 0.780), suggesting that the reason bobolinks were associated with exotic cool-season grass cover in cool-season plantings was likely a result of the total amount of grass cover present in these plantings. Previous studies have also noted that Henslow's sparrow abundances did not differ between cool-and warm-season restorations (Jaster et al 2013). This appeared to be the case at Spring Run as the NMDS shows Henslow's sparrows associated within both cool-and warm-season plantings.…”

Postfledging habitat selection and survival of Henslow’s Sparrow: management implications for a critical life stage

“…During the dependent period, fledglings used an area (~1.5 ha) that was substantially larger than the ~0.29 hectare nesting territory size we estimated by spot-mapping adults during concurrent work (unpublished data), as well as previously published estimates using similar methods (Wiens 1969, Jaster et al 2013. Spot-mapping can sometimes underestimate the area of habitat used by adults (Streby et al 2012), but our observations of fledglings entering neighboring territories with active nests confirms that young birds quickly moved outside the area defended by singing males.…”