EricMorocco
16,732 km
3 stopovers with a longest stay of 124 days
Following Eric, Nico and Sanne
Eric, Nico and Sanne all started near the same stretch of the North Sea coast, but over the next nine months each bird found a different way to northwest Africa and back.
Eric Nico Sanne
The tags followed the birds for just over eight months.
01 The journey
The routes start close together in northern Europe, but they begin to look very different as the birds move down the Atlantic coast.
The Atlantic flyway Scroll to move through time
What happened
They wore the same tags and started from the same part of the coast, but each bird spent the winter differently.
3 stopovers with a longest stay of 124 days
10 stopovers with a longest stay of 19 days
9 stopovers with a longest stay of 101 days
A closer look Their longest stays
The tags tell us where each bird paused, while historical weather gives us a rough sense of the day they arrived and the weeks or months that followed.
02 Timing
Here are the same three routes again, with time on one axis and latitude on the other. When a line moves down, the bird is moving south.
Latitude through time Map transforms into timeline
Eric Nico Sanne
03 Pace
Each row shows one bird and each column shows one day. Darker days mean the bird travelled farther, while pale stretches show days with little movement.
Eric’s two blank breaks are tag outages, lasting 4.2 and 4.6 days. The chart leaves those days empty because no movement was recorded.
One day, from Morocco to Portugal
1,091km in one day
On 20 April 2014, Nico’s return track began over the Atlantic off southern Morocco and ended at Portugal’s Alqueva Reservoir. The route was 94% direct. The GPS fixes show that he moved north for about 19 hours, including several hours in darkness.
From 03:00 UTC, the wind flowed north along Nico’s route. It stayed with him through most of the day.
12:00 UTC57 km/h wind
Along Nico’s path55 km/h tailwind
17 of 20hourly route segments had a tailwind
47 km/haverage tailwind from 07:00 to 16:00 UTC
Why it mattersResearch suggests Lesser Black-backed Gulls may wait for favorable weather to save energy. Read the study.
SourceERA5 hourly wind estimates at 100 m. Streamlines show air flow. Nico flew at varying heights.
Wind across the day
17 of 20hourly route segments had a tailwind
47 km/haverage tailwind from 07:00 to 16:00 UTC
Why it mattersResearch suggests Lesser Black-backed Gulls may wait for favorable weather to save energy. Read the study.
SourceERA5 hourly wind estimates at 100 m. Streamlines show air flow. Nico flew at varying heights.
04 Route shape
To make the routes easier to compare, each one is shown on its own without the map underneath.
Nico went the farthest
Nico travelled 26,991 km, which was 10,259 km more than Eric even though Nico spent the winter along a similar stretch of coast to Sanne.
05 The return
Solid lines trace the outward journey and dotted lines trace the way back.
Nico took a straighter route home
Nico’s return was the most direct part of any journey. It was 63% direct, compared with 24% on the way south. Directness compares the straight line distance with the route the bird actually flew.
06 Your turn
Move through the season one day at a time, or choose one bird and follow its route.
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