Contrasting impacts of invasive plants and human-altered landscape context on nest survival and brood parasitism of a grassland bird
Humans have altered grasslands in recent decades through crop conversion, woody encroachment, and plant invasions. Concurrently, grassland birds have experienced range-wide declines. Studies have reported effects of plant invasions and land conversion on nest ecology, but few have assessed relative impacts of these changes.
We compared impacts of invasive plants and landscape context on nest survival of a grassland songbird, the dickcissel (Spiza americana). We also compared effects on parasitism by brown-headed cowbirds (Molothrus ater) and tested whether parasitism affects survival.
From 2013–2016, we monitored 477 dickcissel nests. We measured nest-site vegetation (including woody plants, tall fescue Schedonorus arundinaceous, and other invasive grasses) and measured landscape context at broad scales.
Nest survival declined with increasing tall fescue cover at nest sites, and parasitism was more common at nests with greater fescue and woody cover. Some evidence suggested a negative effect of row-crop cover within 1000 m on nest survival, but no landscape patterns unambiguously affected survival. Woodland cover and wooded-edge prevalence were associated with reduced parasitism risk. Parasitized nests had smaller clutches, failed more frequently, and produced fewer fledglings than non-parasitized nests.
Determining the impacts of invasive plants and other anthropogenic changes on grassland birds will aid in prioritizing management to improve habitat quality. Our results indicate that optimizing landscape context around habitats may not affect dickcissel nest survival strongly, except perhaps through effects on parasitism. In contrast, controlling tall fescue and shrubs within grasslands could benefit birds by increasing nest success and reducing parasitism.
KeywordsBrown-headed cowbird Dickcissel Grassland birds Spiza americana Tall fescue Woody encroachment
We are grateful to I. Bradley, J. Capozzelli, O. Garza, D. Jen, M. Kneitel, K. Malone, A. Meyer, T. Park, T. Swartz, B. Vizzachero, and A. West for field assistance. We thank J. Rusk, S. Rusk, and R. Harr for managing the pastures; T.J. Benson, T. Lyons, and T. Jones for analytical guidance; T.J. Benson, J. Fraterrigo, and two anonymous reviewers for comments on the manuscript; P. Sterner and the Iowa Department of Natural Resources for access to their lands; and the undergraduates who helped enter data. Partial funding was provided by the Competitive State Wildlife Grants program U-D F14AP00012 in cooperation with the U.S. Fish and Wildlife Service, Wildlife and Sport Fish Restoration Program; by the National Institute of Food and Agriculture, U.S. Department of Agriculture, under award number ILLU-875-918; and by awards to SBN and JJC from the Frances M. Peacock Scholarship for Native Bird Habitat from the Garden Club of America and from the Sustainable Agriculture, Research, and Education, North-Central Region [GSP15-038]. Our nest monitoring procedures were approved by the Institutional Animal Care and Use Committee at the University of Illinois at Urbana-Champaign (IACUC; Protocol #14073).
- Burnham KP, Anderson DR (2002) Model selection and inference: a practical information-theoretic approach. Springer, New YorkGoogle Scholar
- Chalfoun AD, Ratnaswamy MJ, Thompson FR (2002) Songbird nest predators in forest-pasture edge and forest interior in a fragmented landscape. Ecol Appl 12:858–867Google Scholar
- Daubenmire R (1959) A canopy-coverage method of vegetational analysis. Northwest Sci 33:43–64Google Scholar
- Harr RN, Morton LW, Rusk SR, Engle DM, Miller JR, Debinski D (2014) Landowners’ perceptions of risk in grassland management: woody plant encroachment and prescribed fire. Ecol Soc 19:art. 41Google Scholar
- Kirfman GW, Brandenburg RL, Garner GB (1986) Relationship between insect abundance and endophyte infestation level in tall fescue in Missouri. J Kansas Entomol Soc 59:552–554Google Scholar
- Littell RC, Milliken GA, Stroup WW, Wolfinger RD, Schabenberger O (2006) SAS for mixed models, 2nd edn. SAS Institute Inc., CaryGoogle Scholar
- Lokemoen JT, Koford RR (1996) Using candlers to determine the incubation stage of passerine eggs. J Field Ornithol 67:660–668Google Scholar
- Martin TE, Geupel GR (1993) Nest-monitoring plots - methods for locating nests and monitoring success. J Field Ornithol 64:507–519Google Scholar
- Peterjohn BG, Sauer JR (1999) Population status of North American grassland birds from the North American Breeding Bird Survey, 1966-1996. Stud Avian Biol 19:27–44Google Scholar
- Pyke DA (2011) Restoring and rehabilitating sagebrush habitats. Stud Avian Biol 38:531–548Google Scholar
- Ralph CJ, Geupel GR, Pyle P, Martin TE, DeSante DF, Mila B (1996) Manual of field methods for monitoring landbirds. General technical report—pacific southwest research station, USDA Forest ServiceGoogle Scholar
- Rosenberg KV, Kennedy JA, Dettmers R, Ford RP, Reynolds D, Alexander JD, Beardmore CJ, Blancher PJ, Bogart RE, Butcher GS, Camfield AF, Couturier A, Demarest DW, Easton WE, Giocomo JJ, Keller RH, Mini AE, Panjabi AO, Pashley DN, Rich TD, Ruth JM, Stabins H, Stanton J, Will T (2016) Partners in Flight Landbird Conservation Plan: 2016 Revision for Canada and Continental United States. Partners in Flight Science Committee. p 119Google Scholar
- Sauer JR, Niven DK, Hines JE, Ziolkowski DJ, Pardieck KL, Fallon JE, Link WA (2017) The North American Breeding Bird Survey, results and analysis 1966-2015. Version 2.07.2017. Laurel, MD, USA: USGS Patuxent Wildlife Research CenterGoogle Scholar
- Shaffer TL, Thompson FR III (2007) Making meaningful estimates of nest survival with model-based methods. Stud in Avian Biol 34:84–95Google Scholar
- Temple SA (2002) Dickcissel (Spiza americana). In: Poole A (ed) The birds of North America online. Cornell Lab of Ornithology, IthacaGoogle Scholar
- United States Department of Agriculture National Agricultural Statistics Service (2017). https://www.nass.usda.gov/Research_and_Science/Cropland/Release/index.php. Accessed 25 Nov 2016