Night herons preparing for migration at Mud Lake
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As I drove into the South Boat Ramp on Mud Lake on Wednesday evening, 17 young, black-crowned night herons flew up from a pond and into the willows. It did not take them long to wiggle along the flimsy willow canes to become hidden in the thick foliage, and before I stopped, none were visible.
I continued my drive down the south side of Mud Lake watching great blue herons, snowy egrets, a great egret and a family of American bitterns — along with thousands of American coots, a hod-podge of ducks and other waterfowl. Northern harriers and Swainsen’s hawks were working the willows and edges of the agriculture fields looking for rodents, while the great blue herons appeared to be more successful at catching the rodents.
But my desire was to see when the black-crowned night herons would come back out to do their hunting for food. Their name is derived from their habit to hunt in the late evening through the night until dawn. Experts assume that this time is best suited for them because of all the competition they have during the daylight hours from other herons and egrets. I have seen them hunting on cloudy days, but only occasionally.
So, back to the pond I went. I set up at the best place to observe the willows where I saw most of them disappear. While waiting, several times a harrier would fly over the shallow pond, and I would hear the “kwok” sound coming from the herons hidden in the willows. The late hatches of coots who could not fly yet would scurry for cover into the tall grass or reeds.
Clouds covered the setting sun when I noticed a young heron position itself near the water’s edge. Then I watched as three adults showed themselves higher in the willows. It was not long before I could make out 12 immature herons at the edge of the thick willows, but they all walked or flew back in when a young bald eagle flew over.
It was almost dark when I finally observed the three adults and several young birds start hunting in the shallow pond. I watched one young bird, who appeared to be very young and could hardly fly, be fed the regurgitated puree from one of the adults. It will need to mature quickly to be ready to migrate in less than a month to the southern states.
Their migration should start in three to four weeks when some of the shallow waters begin to freeze over. The black-crowned night herons are opportunistic feeders and will eat almost everything “dead or alive” that is animal, bird or plant matter. However, most of what they eat are fish. They do not have long legs, so if the edges of the ponds freeze over, they are without breakfast and lunch.
Their migration to southern states usually starts in late September or early October, and they will travel in small to large groups of birds up to 200. They also travel during the night, finding a suitable rest area during the day. If they find a good feeding area, they may stay a couple of days to refill their energy needs.
It you want to observe these birds before they leave, late evening and early morning on the southside of Mud Lake is a great place. You can also watch other species of birds preparing to migrate in that area. Thursday evening, I observed a flock of about 30 great blue herons flying along the south-east side of Mud Lake.
