Vernon's Great Blue Herons - nests full of large chicks

Vernon's Great Blue Herons at the colony along 24th Street laid their eggs in March and April, incubated them through the latter half of April and the first half of May and are now (4 June) busy feeding the resulting chicks. Some nests are crowded with as many as four young herons per nest.

In some of the few nests that are still visible against the green canopy of cottonwood leaves the young are still kneeling in the nest. These scraggly ragamuffins are covered in a messy mix of punk spiky feathers and remnant down. Their body feathers are growing nicely and they are quite dark compared to their parents. However, the careful observer can discern a dark crown, and a whitish throat.

In other nests the chicks are older, larger and are standing. A heron's nest is not very large and three or four large youngsters pretty much fill all the available space. When one of the parents arrives with food, it must stand on the edge or on a supporting branch while the kids go wild with appetite. The nest becomes a cauldron of hunger, the chicks grabbing at the parent's bill. It's amazing nobody loses an eye. The parent regurgitates and the chicks fall to grabbing at whatever comes up.

Juvenile Great Blue Heron not long out of the nest - Crescent Beach, B.C. - 22 April 2010 Copyright Chris Siddle.  

The photo above captures the overall dinginess of a fledgling Great Blue fairly well. The chicks in the Vernon colony, however, have darker crowns that the one shown here.

The parents are kept busy foraging for food for their growing chicks. An adult doesn't tarry very long at the nest. Once the feeding has been completed, the adult may move away a few metres from the nest for a rest or may launch itself away for another hunting trip.

The parents may fly north towards Swan or Otter lakes, west toward Goose Lake or over the Bella Vista Range to Head of the Lake, southwest to Okanagan Lake or south to Kalamalka Lake. Some fly due east up the BX Creek valley. They are not all headed to bodies of water. Some forage in fields and pastures for rodents.

With the adults departing from the colony in a variety of directions, it's easy for the observer to image the heron colony as the hub of a wheel or the centre of a simple web, the strands marked with arrowheads to show the direction of the flow of energy in the form or food for the chicks from ponds, lakes, and fields back to the colony.

However, besides continuing to grow, there is at least one major developmental step the young herons must take before they leave the colony. Once they have a full set of primaries and secondaries they must learn to fly. The first drill is learning to flap while staying in place on the nest.

BLACK SWIFT UPDATE

Before I close, I would like to note that this spring, in spite of being absent for several days, I saw Black Swifts over Swan Lake as I have almost annually for the past 20 years (see blog entry for 31 March 2013). On 1 June I noted about 10 Black Swifts at medium height over the south-east shore of the lake.

GRASSHOPPER SPARROW UPDATE

My search of the grasslands on the east side of Goose Lake early on 6 June turned up no Grasshopper Sparrows. Clay-coloured Sparrows were frequent in the hawthorn thickets, but there was no sign of GRSPs among the grass tussocks.

COMMENTS

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