Assessing Florida Mottled Duck/Mallard Genetic Introgression

by Ron Bielefeld

This past November, we headed into the field to start data collection for a long-awaited study to assess the extent to which the Florida mottled duck population has been compromised by mallard genetic introgression. The data to be collected were thousands of high-resolution photographs of specific feather groups on individual ducks.  We will use these photographs in conjunction with a plumage-based identification key we developed to segregate pure mottled ducks from mallards/hybrids.  Ultimately, our objective is to estimate the proportion of pure birds remaining in the population.

A mottled duck/mallard hybrid with a wing up showing the key hybrid characteristic of an extensive white wing bar on the leading edge of the speculum.

During November 2016 – February 2017 we traveled over 13,000 miles of Central Florida’s back roads and city streets visiting 433 wetland sites. We were able to complete data collection for all but a small portion of our Central Study Region. At these wetlands, we observed 1,062 and obtained photographic data for 824 ducks. Our goal for the Central Study Region was 2,000 ducks from 380 wetlands.

The proportion of pure mottled ducks to mallards/hybrids in the Central Study Region sample is still to be determined. Keying out the individual ducks from the thousands of photographs using the identification key is our next step. After that, we are back into the field in November 2017 to start data collection in the South Study Region.  We should be done collecting data in all three study regions (North Study Region is the last region) by the end of February 2019.