Warbler Watch: They’re Migrating Again

In the middle of August I begin to anticipate the birds migrating southward who will begin showing up in Eliza Howell Park before the end of the month. I am thinking, at this particular time, of one species (Common Nighthawk) and a whole bird family (Warblers). I hope to comment more on Nighthawks in another post. This is about the warbler migration. Many warblers are now leaving the North Woods and heading our way.

Invitation: Detroit Audubon is sponsoring a bird walk at Eliza Howell Park on Saturday, September 8, starting at 8:00 a.m. The event is open to anyone interested and there is no cost.

Of the 20 or so warbler species that pass through the park on their way south each year (most from late August to late September), a select few are pictured here with a range/migration map for each. The yellow section on the map is the breeding range, the purple is the winter range, and the pink indicates the areas over which they migrate.

Canada Warbler

Canada warbler

Canada Warbler Migration

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All the warbler photos in this essay were taken by Margaret Weber.

The maps are from Tom Stephenson and Scott Whittle, The Warbler Guide, 2013.

Most warblers are long-distance migrants that spend much less time in their North Woods breeding habitat than on the wintering ground and in migration. It was only a short time ago, in May, when they last passed through here, as they headed north. Since then, they have built nests, incubated eggs, fed their young, and are now heading back to locations where insects can be found throughout the winter months.

Magnolia Warbler

Magnolia 2018

Magnolia Warbler Migration

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When we last saw migrating warblers in Detroit in May, they were in their bright breeding plumage, as represented in these pictures. Now many of them will be arriving in a somewhat different and somewhat duller fall/winter look. The process of learning to identify warblers involves learning the visual variations from spring to fall, a sometimes challenging project that may take a few years. Fortunately, the Fall migration is spread over more weeks than the brief intense Spring migration so there is a little more time to develop field skills.

Chestnut-sided Warbler

Chestnut_sided_2018

Chestnut-sided Warbler Migration

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Annual bird migration is a fascinating natural phenomenon. Warblers are very small birds. Chestnut-sided Warblers, for example, are 4 – 5 inches in length and weigh about 0.4 oz. Most of the tiny warblers migrate a couple thousand miles twice each year. It is hard to imagine the energy required, but easy to understand the fuel stops along the way. Since many small birds migrate at night, early morning, as soon as it is warm enough for insect activity, is often a good time to see them as they begin to feed.

Blackburnian Warbler

Blackburnian_2018

Blackburian Warbler Migration

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I don’t expect to see every migrating warbler species every Fall in EHP; their stops are brief and not always in the same location. Good bird observations often result from being “in the right place at the right time” and the right place and time cannot always be predicted with full accuracy. Based on past experiences and years of records, however, I can quite confidently predict that Blackburians will be visible and that they will be among the warblers seen before the end of August. Some of them do not have far to fly from their breeding ground to Detroit.

Wilson’s Warbler

wilsons warbler

Wilson’s Warbler Migration

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As can be noted from the maps above, many warblers that are seen in eastern United States are not found in western states. Wilson’s warbler is an exception. It migrates through/over almost every state.

—–

There is a saying common among social justice advocates and environmentalists: “Think globally, act locally.” The big picture provides the context and, at times, the incentive for effective and significant local projects and behavior.

In a somewhat similar way, local nature observation and appreciation can be even more enriching and satisfying with an awareness of the big picture. When I see warblers stopping in the park on their way south over the next several weeks, I am thrilled just to see them but also impressed and amazed at where they have been and where they are going.

 

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