Wildlife at risk: Prothonotary Warbler

Why is the Prothonotary Warbler considered rare? It seems every time someone utters the magic word, Prothonotary (pro-THON-eh-Ter-ee), everyone goes a little bird crazy. The Prothonotary Warbler is a life bird for many birders; some have seen it only once or twice in their lifetime. Warblers in general are hard to spot, and have been known to cause serious next strains due to their minute size. The Prothonotary Warbler is no different, measuring at 14 cm, it’s especially hard to distinguish among branches and leaves. But more so, these warblers are threatened by habitat destruction, declining food resources, weather variations, and parasitic species. This warbler is listed as endangered in Canada. An estimated 2,000 pairs live in South Carolina’s protected, Francis Beidler Forest.

Prothonotary Warbler in Prospect Park, New York.

This Prothonotary Warbler was taking a stroll around Prospect Park, NY in April. Image Credit: Marc Brawer

See my colors

Among a sea of green leaves, the Prothonotary Warbler’s deep yellow head and underparts stands out. The prothonotary has greenish upperparts, and unmarked bluish-gray wings, white belly and undertail. This helps distinguish it from other yellow warblers. Adults females and immature birds are of a similar shade but with a duller composition. Plumage stays the same throughout the year. If you hear a series of high-pitched tweet-tweet-tweet, sharp and loud, you’ve found it!

Where I call home?

The Prothonotary Warbler is a bird of the southern woodland swamps with a high concentration along the floodplain forests of Lower Wisconsin, Mississippi, and the St. Croix rivers (common to abundant). In the summer they range from southern New Jersey to north-central Florida, west to east-central Texas to southern Michigan. It’s also a visitor of the Appalachian Mountains, sparingly distributed in the northern parts of the states. Their winter range extends from Southern Mexico to Venezuela, and sometimes the warbler plays the role of the island bird in Puerto Rico and Bermuda.

This species breeds in moist bottomland forests either permanently or seasonally flooded with standing water such as sloughs, oxbow ponds and slow-moving backwaters. It tends to find safety above flooder water, which has less risk of nest predations by raccoons— their main nest predator. To defend their territories the tiny male warblers snap their bills and chase away intruders. Males keep watch while the female builds the nest and lays eggs—what a gentleman! To flourish these birds must find breeding habitats in overstay trees with the right kind of cavities for nesting. Typically low cavities such as old Downy Woodpecker holes. Some of the trees they flock to include the swamp white oak, silver maple, green ash and river birch, among others.

 

Why I’m considered rare?

The Prothonotary was included in the 2014 State of the Birds Watch List, due to its vulnerable nature and niche habitat. Prothonotaries are prone to suffer from unpredictable ecological changes. For example loss of wetland habitats affects both breeding and wintering grounds. Logging practices are specially harmful to these warblers, since it removes cavity trees. Also some plants like the Reed canary grass, which can dominate the ground layer, impede new trees from growing, thereby turning the bottomland hardwoods unsuitable for Prothonotaries to survive. They also face parasitism from Brown-headed Cowbird, who are known to abandon offsprings in foreign nests. This behavior ruins the warbler’s chance at hatching success, further increasing nestling mortality. In southern Illinois parasitism rates are as high as 50 percent for Prothonotaries.

Climate change is causing a decline in soil moisture, reducing the growth of bottomland hardwood forests, and in turn decreasing available habitat for the birds.  Frequent summer storms and flood events also have a negative impact; they destroy low nests, as it occurred in the Wisconsin River in recent years. Extreme droughts dry backwater sloughs and ponds essential for the warbler’s survival against predators. The overall population is projected to dwindle as the southern part of its main range suffers.

 

Help a bird out

Now that you know about the wildlife at risk: Prothonotary Warbler, plan out some simple ways you can help out this species. During winter, prothonotaries live in mangrove forests; if you have one near you, be sure they’re kept healthy. One sure way to lure these sweet, yellow warblers is by offering a safe habitat for nesting in your backyard. They typically thrive in nesting huts and nest boxes, and are especially drawn to living near water, such a large garden pools, ponds, and marsh. Their favorite trees include willow oak, sweet gum, black gum, bald cypress, tupelo, elms, and river birch. Offer them fresh fruits like apples, oranges, and bananas to keep them around. As everyone knows with warblers, one minute you see them, and the next they’re gone!

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