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The Story of Mr. Bisbing, Part III: Spending the Summer at the Outer Banks

July 21, 2014

This is the third chapter in the story about a great egret that we gave a GPS tracking device on the Outer Banks of North Carolina in spring 2013 (see photo). We followed his movements for about 8 months and reconstructed his story with his GPS and ACC data (see parts I and II).

BisbingBuckler

Mr. Bisbing, a great white egret with our tag on his back.

On July 17th Mr. Bisbing got up before dawn (5:05 am to be precise) and took off for a major change in his life. Breeding season was over, his offspring were on their own by now, so he could have some fun in a maybe more diverse environment.
So he took off, flying south, along the coastline (Fig. 1). After 45 min he took his first break right behind the city of Duck at the beautiful sound. During this first stage of his trip south he covered about 32 km (20 miles). But the new area seemed not to be very interesting, at least we couldn’t observe any foraging behavior in the Accelerometer (ACC) data (Fig. 2), so he took off again at 6 am and flew for another 12 min, 9 km (5.6 miles) further south. He rested again, maybe checking for some food, and as nothing interesting showed up, he kept going south. On the whole Mr. Bisbing took 6 stages to cover a distance of about 71 km (44 miles) which took him about 70 min flight time and a little over 4 hours all together.

PartIII_Fig1

Figure 1. Mr. Bisbing’s migration from Monkey Island to the south of Roanoke Sound. The pink line shows his movement tracks, the yellow rings indicate his resting areas.

Eventually he arrived at 9:20 am at his new home for the rest of the summer: a small island between Hog and Cedar Island in the south of Roanoke Sound.

PartIII_Fig2

Figure 2. ACC-data from the morning of July 17th showing Mr. Bisbing’s flying and resting activities during his first observed migration. Dark grey shows time before sunrise.

After this long and strenuous flight Mr. Bisbing was certainly hungry and needed a meal, so he started foraging and spent the rest of the day island hopping around his new roost site, searching for food (Fig. 2). The first night was a little rough, and it took him until midnight to finally settle down and sleep calmly (Fig. 3), but from the next day on, he fell into a regular and relaxed routine.

PartIII_Fig3

Figure 3. First day at the new foraging area and night at the roost south of Roanoke Island. Grey bars show times after sunset.

 Mr. Bisbing usually woke up around 5:40 a.m. and left his roost around 5:50 a.m., quite punctually every day. From the roost, he first flew south to the wetlands of an island west of the Oregon inlet (Island C). He spent most of the day there, but sometimes checked the wetlands east of the Bodie Island Lighthouse or east of Tommy Hammock, before he went back to his roost for the night between 5:30 and 8:30 p.m. (Fig. 4).

PartIII_Fig4

Figure 4. Mr. Bisbing’s foraging area from July 18th until September 27th. The pink line shows his movement tracks.

 He stayed in the area south of Roanoke Island until October 24th, but decided that another change was necessary on Sept. 27th. From that day on, he roosted 5 km (3.1 miles) farther south on Island C, west of Oregon Inlet. This was the island where he used to go foraging every day. He also changed his foraging preferences. From now on, he chose more and more often to forage south of the Inlet, an area, that he didn’t use before at all (Fig. 5).

PartIII_Fig5

Figure 5. Mr. Bisbing’s foraging preferences after Sept. 27th, until Oct. 24th. The pink line shows his movement tracks.

 As autumn wore on and temperatures got chilly, his daily schedule became more and more irregular, and his foraging trips took him farther and farther south. He flew up to 19 km (12 miles) south from his roost to forage – a long distance for a daily routine. Perhaps this was training to get prepared for his next big adventure – a huge migration south of the Outer Banks, heading out over open ocean. Read more about it in our next post in a couple of days!

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