https://navionics.secure.force.com/k...s-on-the-Chart
The pink/purple birds/ducks indicate different types of marine sanctuaries or estuary area zones/nature reserve areas. These can be environmentally sensitive sea areas or areas with minor restrictions and/or information notices. The same icon is used in the NOAA (government) charts:
https://nauticalcharts.noaa.gov/publ...s-chart-1.html, on page 72.