FIGURE 6.

Migration routes of four ring-billed gulls that nested in Duluth, MN (A). Locations detected by GPS of gull 72L for the 2019-2020 years are shown as red dots and lines against a background of the United States with areas of gull presence shaded in green (breeding grounds), blue (migratory zones), lavender (non-breeding grounds), or yellow (locations with gulls present all year). The dots represent sites the gull remained for several months and lines are the inferred migration routes. (B). GPS locations detected for gull 79L during the 2019-2020 years are shown as magenta dots and lines against a background of the United States with areas of gull presence shaded in green (breeding grounds), blue (migratory zones), lavender (non-breeding grounds), or yellow (locations with gulls present all year). The dots represent sites the gull remained for several months and lines are the inferred migration routes. (C). GPS locations detected for gull 80L during the 2019-2020 years are shown as blue dots and lines against a background of the United States with areas of gull presence shaded in green (breeding grounds), blue (migratory zones), lavender (non-breeding grounds), or yellow (locations with gulls present all year). The dots represent sites the gull remained for several months and lines are the inferred migration routes. (D). GPS locations for gull 81L during the 2019-2020 years are shown as green dots and lines against a background of the United States with areas of gull presence shaded in green (breeding grounds), blue (migratory zones), lavender (non-breeding grounds), or yellow (locations with gulls present all year). The dots represent sites the gull stayed and lines are the inferred migration routes. The pie charts accompanying figures (B–D) represent the location each gull what in at the corresponding time of year. The same colors are used for location as are used in figures A, B, C, and (D). Limited temporal information was detected for gull 72L, therefore a pie chart was not created. (E). Dotted lines represent the migration routes for four ring-billed gulls (72L (red), 79L (magenta), 80L (blue), 81L (green)) inferred from GPS location data submitted from geolocators affixed to the animals for the 2019-2020 years. The four North American avian flyways (Pacific, Central, Mississippi, Atlantic) are shown in the background for context. Background maps in Figures 5A–D are from images obtained from Wikimedia Commons under the Public Domain Dedication. Large circles and paths were drawn to account for the uncertainty in the granular details of the gulls’ paths.