A Green Heron Stalks the Shallows

Article by Jeff Hiebert, NFN Member

Over the past few years, I have come to appreciate how beautiful and wonderful birds are. Along with that appreciation has been the realization that there are diverse birds within a short walk or drive of my home. I have encountered new species of birds almost every time I go out to my new favourite birding destination: Long Point. Globally renowned for being a biodiversity hotspot, and a corridor for migrating birds crossing the Great Lakes, Long Point is full of a variety of freshwater habitats and a corresponding diversity of bird species.

My most recent exciting encounter was with a species I had never before seen up close. Before this past year “Heron” meant the Great Blue Heron (Ardea herodias), the only species of heron I saw regularly, certainly the most conspicuous heron species across North America. But as I was wandering down a trail amid mudflats and shallow coastal marsh, I was treated to an incredible sighting: the small agile form of a Green Heron (Butorides virescens).

Stalking swiftly through the shallow water, the Green Heron snapped at the water surface with fair frequency and was always on the move while it foraged. I wasn’t sure exactly what it was eating, but it certainly wasn’t fish unless it was catching tiny individuals. My guess is that it was feeding on aquatic invertebrates such as dragonfly larvae, or other water-dwelling insects. I couldn’t believe my luck to see this beautiful little hunter foraging within a few metres of me.

Green herons breed across the eastern United States and Southeastern Canada (including Southern Ontario). The birds start arriving in Ontario at the end of April and are gone by the end of October (Davis and Kushlan 2020).

This photo of the Green Heron shows it off in a more “typical” Heron pose, demonstrating how long its neck is.

Green herons spend the winter in Mexico, Central America and Northern South America. Throughout their range they utilize essentially any fresh or salt-water habitat from inland marshes to coastal mangrove forests (Davis and Kushlan 2020). With such a diversity of habitats, they feed on a wide range of prey depending on where they are hunting including fish, frogs (and tadpoles), lizards and snakes, rodents, crayfish and crabs, aquatic and flying insects, spiders, snails, earthworms and leeches (Davis and Kushlan 2020). Besides these aquatic organisms, they even feed on such surprising prey as nestling birds (Wiley 2001). Clearly Green Herons are opportunistic foragers using a variety of feeding methods to capture such diverse prey.

One of the most fascinating foraging behaviours is bait-fishing. Several birds are known to do this*, but Green Herons are the heron most frequently observed using this strategy to catch prey. In one of the first reported instances of bait-fishing in the Green Heron (Lovell 1958) the bird used bread thrown by people to attract fish to the surface and even chased American Coots (Fulica americana) away from its bait.

*Many herons have been reported to use bait such as the Black-crowned Night Heron (Nycticorax nycticorax), the Great Blue Heron (Ardea herodias) and the Great Egret (Ardea alba), but other birds are also reported bait-fishers, such as the Pied Kingfisher (Ceryle rudis) and the Black Kite (Milvus migrans). Check out this article for more fascinating details: Davis and Zickefoose 1998 (Bait-fishing by Birds: A Fascinating Example of Tool Use | Searchable Ornithological Research Archive (unm.edu))

The individual that I watched wading through the shallows was not using any bait-fishing techniques, but rather seemed to be doing the more commonly observed stalk-and-stab technique of herons the world over. After roaming across the patch of water directly across from me, it took to the air and flew a short distance to begin combing a new area of wetland for food. What a beautiful, amazing bird.

References:

Davis Jr., W. E. and J. A. Kushlan (2020). Green Heron (Butorides virescens), version 1.0. In Birds of the World (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.grnher.01

Wiley, James. 2001. Green Heron (Butorides virescens) predation at Village Weaver (Ploceus cucullatus) nests. Journal of Society of Caribbean Ornithology Vol 14 No. 3 pp 130-133. (https://jco.birdscaribbean.org/index.php/jco/article/view/571/475)

Lovell, Harvey B. 1958. Baiting of Fish by a Green Heron. The Wilson Bulletin Vol. 70, No. 3 (Sep., 1958), pp. 280-281

Davis, William E. and Zickefoose, Julie., 1998. Bait-Fishing by Birds: A Fascinating Example of Tool Use. Bird Observer Vol. 26 No. 3, pp 139-143.

Link to YouTube video of foraging green heron
https://youtu.be/1xfKXI4Y1KY

link to Jeff’s blog post is:
https://norfolknaturalist.ca/2022/07/14/a-green-heron-stalks-the-shallows/