Bald Eagle

Eagle Time and GMT

When you click on any data point on the bald eagle map you'ill find interesting information. This information comes from the signals sent back and forth from the eagle's backpack PTT and an orbiting satellite. We receive information about the eagle's latitude and longitude AND the time of day the signal is sent.

Information from the Bald Eagle Map Server

Understanding Time and Eagle Sightings
How many hours are there in one day? 24! Imagine the world sliced into 24 pieces, like sections of an orange. Each section is a time zone. Each time zone differs from its adjacent time zone by one hour (earlier or later), so that the local times align with the local solar times of sunset and sunrise. The time in each one of these time zones is called the local time.

Local Time is Meaningless to a Satellite
Remember, the satellite is zooming around the earth every 101 minutes, so local times on Earth are a blur.

Scientists use just one single uniform time zone all around the world. This makes it easier to know what the time is at another location.

So what time IS it where the eagles are, local time?
After all, local time DOES matter to an eagle whose behavior is regulated by earth's day/night cycles.

The eagle satellite transmitter times we receive from ARGOS are GMT (Greenwich mean time). GMT is based on the local time in Greenwich, England. It is also called UT, Universal Time, or Z, Zulu.

During daylight savings time, GMT is 4 hours ahead of Eastern Daylight Time (EDT) where the eagles are sending signals. To convert GMT to EDT subtract 4 hours from the GMT.

Example: 21:46:31 (GMT) – 4 hours = 17:46:31 (EDT)

Critical Habitat = Night Roost
Peter Nye studies the time of sightings to help protect the eagle's habitat.

Night Roosts
If sighting are between 18:00 EST and 06:00 EST, the eagles are in their night roost and are not moving.

Night roosts are some of the most critical habitats to wintering bald eagles, especially in severe winter weather, so we like to be able to isolate those for mapping purposes to see if patterns of regular/annual use, so we can pursue protection of those sites if needed.

Try This!
Help Determine Critical Habitats
Look at the real data sent directly from the satellite from ARGOS. Practice converting GMT to EDT. Then decide if the signal time is during the night when eagles are roosting.

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