Survivorship and mortality patterns of double-crested cormorants at Spider Island, Wisconsin, 1988–2006

Item Metadata

Dublin Core

Title

Survivorship and mortality patterns of double-crested cormorants at Spider Island, Wisconsin, 1988–2006

Description

Banding records were examined to identify changes in mortality causes and locations of Double-crested Cormorants (Phalacrocorax auritus) in Door County, Wisconsin. In 14 out of 18 years between 1988 and 2005, a total of 22,469 birds were banded (300 to 5,462; average 1,605 per active banding year). Of 649 usable band returns (36.1 ± 5.4 per year), 33% were banding-year recoveries (before 1 May of the first year of life). The yearly rate of banding-year recoveries increased from 0.7% per year before 1996 to 2.2% per year after 1999. The yearly proportion of all band recoveries attributed to animal damage control operations also increased over time. The yearly proportion of band returns from Mississippi Delta states increased over time. Mortality rates, both natural and anthropogenic, of cormorants from these colonies appear to have risen as the population has grown and control activities in southern states have increased. Apparent survival rates were estimated by mark-recapture methods during 2001 to 2006. Birds color-banded as adults had a model-averaged annual survival rate of 0.696. For birds banded as nestlings, the model-averaged survival rates were: 0.305 (first year), 0.774 (second and third year), and 0.633 (adults). Simulations of these measured survival rates combined with previously estimated reproductive rates demonstrated that emigration and immigration rates complicate interpretation of these results. Also, simulations demonstrate the potential efficacy of reproductive controls in reducing local breeding populations.

Bibliographic Citation

Stromborg, K. L., J. S. Ivan, J. K. Netto, and C. R. Courtney. 2012. Survivorship and mortality patterns of double-crested cormorants at Spider Island, Wisconsin, 1988–2006. Waterbirds 35:31–39. https://doi.org/10.1675/063.035.sp105

Creator

Stromborg, Kenneth L.
Ivan, Jacob S.
Netto, John K.
Courtney, Chad R.

Subject

Bird banding
Double-crested Cormorant
Lake Michigan
Mark-recapture
Mortality
Survival

Extent

10 pages

Date Created

2012-12-01

Type

Article

Format

application/pdf

Language

English

Is Part Of

Waterbirds

Collection

Citation

Stromborg, Kenneth L. et al., “Survivorship and mortality patterns of double-crested cormorants at Spider Island, Wisconsin, 1988–2006,” CPW Digital Collections, accessed February 27, 2024, https://cpw.cvlcollections.org/items/show/284.