Identifying conservation opportunities for species of conservation concern in managed ecosystems

Background/Question/Methods

The need species conservation beyond protected areas is increasingly evident. However, for these efforts to be successful, data are needed to 1) test if mechanisms of response differ between natural and managed ecosystems, 2) set appropriate conservation targets, and 3) optimize investment for conservation in managed ecosystems, including in agricultural ecosystems. These data need to include suitable measures, of successful conservation action beyond abundance and occupancy. Thus, to assess the conservation value of shrubland habitat embedded in different land uses at local and landscape scales, we evaluated nesting success of a shrubland bird species of conservation concern, Bell’s Vireo (Vireo belllii). In 2012 we monitored nests at eighteen field sites in the Western Cornbelt agroecoregion. We classified field sites in one of three landscape categories; protected area, conventional farmland, and organic farmland. As a measure of local land use we estimated percent cover of different local land uses at 50m from each nest. Estimates of daily nest survival rate were modeled in Program MARK.  

Results/Conclusions

We located sixty-five nests between May 1 and August 1, 2012. We found most nests in shrubland embedded in protected habitats (n=43), followed by organic (n=19), and conventional farmland (n=3). Of these, fifty-six (56) had at least one egg. Percent nest success (measured as at least one fledgling leaving the nest) was not different between landscape categories, farmland and protected, nor was there any difference based on the type of dominant land cover, grass and arable, that the shrub cover was embedded in. Seven nests were parasitized by Brown-headed Cowbirds. No difference in rates of parasitism was evident between farmland and protected areas.

Daily nest survival rates (DSR) was best predicted by incidence of brood parasitism. Analysis of nests not parasitized suggests DSR is influenced by both crop and non-crop land use patterns. DSR was lowest at nests embedded in alfalfa fields and adjacent to roads.  DSR was greatest at nests adjacent to mowed grass strips and soybean fields.

These data suggest equal opportunities to conserve Bell’s Vireo and other shrubland birds across land use types.  More importantly, they suggest costs and benefits of multiple land use types not always considered in conservation for species of conservation concern.