Breeding Red-winged Blackbird Response to Conspecific Models Placed in Pre-copulatory Position: Implications for Reproductive Control

Authors

Laurel L. Moulton, North Dakota State University, Fargo
George M. Linz, USDA/APHIS/WS National Wildlife Research CenterFollow
William J. Bleier, North Dakota State University, FargoFollow

Document Type

Article

Date of this Version

January 2008

Comments

Published in National Sunflower Association Research Forum Papers 2008.

Abstract

Sunflower producers in the northern Great Plains are annually plagued by feeding flocks of blackbirds, especially red-winged blackbirds (RWBL). Increased sunflower production and concomitant human-blackbird conflicts have prompted sunflower producers to demand that management strategies be developed to reduce the annual crop losses estimated at ≥ $10 million (Linz et al. 1996). Past techniques aimed at reducing blackbird damage have had varying degrees of success and the annual loss of sunflower remains the same (Peer et al. 2002). Thus, there is a need for new innovative approaches to managing blackbird damage.

One approach is to find non-lethal species-specific methods of lowering reproduction by discovering vulnerable behavioral tendencies in the reproductive cycle of RWBL. Male RWBL are a good candidate for reproductive control because of their territorial and polygynous reproductive behavior.

We have designed a study to assess the male RWBL response to a model placed in pre-copulatory position under different treatment scenarios. Our objective is to discover the conditions under which we can attract the largest numbers of males to the model. Because extra-pair copulation occurs frequently in this species, it may be possible to attract both neighboring males as well as non-territorial floater males to the models (Gibbs et al. 1990). The majority of floater males are second-year (SY) males that are out competed for territories by older males and have a duller plumage than breeding after-second year (ASY) males (Rohwer, 1978). Models could potentially be used as a delivery system for a reproductive inhibitor. This study is a first-step toward discovery of a new species-specific approach to potential reproductive control in RWBL.