Measuring Habitat Quality for Least Bitterns in a Created Wetland with Use of a Small Unmanned Aircraft
- 868 Downloads
Created wetlands play an important role in the conservation of Least Bitterns (Ixobrychus exilis) by compensating for the loss of natural wetlands. In 2011, we studied habitat relationships of a major population breeding in a 128-ha cattail- and bur-reed-dominated impoundment in Quebec. We surveyed for bitterns and recorded habitat parameters at 30 points, making novel use of a small unmanned aircraft system (UAS) to obtain fine-scale land cover data. A model-selection approach based on Akaike’s information criterion (AIC) determined that breeding density was best predicted by cattail cover in combination with water-vegetation edge density (Akaike weight = 0.88). Breeding density was unrelated to water depth, contrary to a previous study at the site after a dyke breach significantly lowered water levels, suggesting that above a certain depth threshold other habitat preferences take precedence. We recommend that management of created wetlands for Least Bitterns focus on maintaining stable water levels of at least 25 cm on average during the breeding season and manipulating them as required later on in order to promote hemi-marsh conditions. UAS can enhance wetland habitat research and monitoring by improving the precision and efficiency of data collection in the field while reducing disturbance compared to ground-based surveys.
KeywordsIxobrychus exilis Species at risk Habitat use Artificial wetlands Remote sensing Aerial survey
We thank B. Jobin, L. Robillard, J. Tardif and S. Giguère for assistance with bittern surveys, H. Gilbert and A. Lachance for the botanical survey, G. Maillet for assistance with the UAS survey, G. Lewis for assistance with aerial image processing, and K. Panchuk and R. Gagnon for coordinating access to the study site. Funding and in-kind contributions were provided by the Kenneth M. Molson Foundation, Environment Canada (Interdepartmental Recovery Fund for Species at Risk), the Department of National Defence, the Canadian Wildlife Federation, Pix4D, Aerial Insight, MicroPilot and the Fonds Québécois de la Recherche sur la Nature et les Technologies.
- Burnham KP, Anderson DR (2002) Model selection and inference: a practical information-theoretic approach. Springer, New YorkGoogle Scholar
- Environment Canada (2014) Recovery strategy for the Least Bittern (Ixobrychus exilis) in Canada. Species at Risk Act Recovery Strategy Series, Environment Canada, Ottawa. http://www.registrelep.gc.ca/document/default_e.cfm?documentID=1291
- Gilbert H (2011) Inventaire botanique en 2011 des étangs aménagés de Baie-du-Febvre – Rapport sommaire: comparaisons 2005–2011. Unpublished report by the Bureau d’écologie appliquée presented to Environment Canada, Quebec CityGoogle Scholar
- Jobin B, Latendresse C, Robillard L (2007) Habitats et inventaires du Petit Blongios sur les terres du Ministère de la Défense Nationale à Nicolet, Québec, étés 2004, 2005 et 2006. Technical Report Series no. 482. Canadian Wildlife Service, Environment Canada, Sainte-FoyGoogle Scholar
- Kent T (1951) The Least Bitterns of Swan Lake. Iowa Bird Life 21:59–61Google Scholar
- McGarigal K, Marks BJ (1995) FRAGSTATS: spatial pattern analysis program for quantifying landscape structure. General technical report PNW-GTR-351, United States Department of Agriculture, Forest Service, Pacific Northwest Research Station, PortlandGoogle Scholar
- Poole AF, Lowther P, Gibbs JP, Reid FA, Melvin SM (2009) Least Bittern (Ixobrychus exilis). In: Poole AF (ed) The Birds of North America. Cornell Lab of Ornithology, Ithaca, no. 17Google Scholar
- SARA (2002) Bill C-5: The Species at Risk Act. Parliament of Canada, Ottawa. http://www.parl.gc.ca/About/Parliament/LegislativeSummaries/bills_ls.asp?lang=E&ls=C5&Parl=37&Ses=2&source=Bills_House_Government
- Weller MW (1961) Breeding biology of the Least Bittern. Wilson Bull 73:11–35Google Scholar