Ask Kenn: Why Have Roseate Spoonbills Invaded the North This Summer?

Question:  Why did we see so many Roseate Spoonbills, Wood Storks, and other wading birds in northern states this summer? What caused this invasion? 

Kenn Kaufman: In 1938, the National Audubon Society sent Robert Porter Allen on an urgent mission: to study the endangered Roseate Spoonbill in Florida, where fewer than 20 nesting pairs remained. So Allen left his home on Long Island, New York, and spent months camping on remote islets in Florida Bay, producing some of the first studies ever of these enigmatic pink waders. Thanks partly to his research and to dedicated conservation efforts, the Florida population of spoonbills eventually made a strong comeback.  

I wonder how Allen would have felt if he could have witnessed this year’s spoonbill flight. In summer 2021, Roseate Spoonbills have shown up all over the eastern United States, as far north as New England and the Great Lakes. At least a couple were on Long Island itself.  

The flight is still under way as I write this, and it will take time for compilers to tally all the details, but this is certainly one of the biggest spoonbill invasions recorded to date. At its northern extent, New Hampshire, Massachusetts, and Michigan all had their first records ever. Individuals were scattered around upstate New York and every coastal state from Connecticut south. Several places saw multiple spoonbills: three together at spots in Pennsylvania and Virginia, four together in coastal Delaware, and five together in southeastern West Virginia. Along the southern coast of North Carolina, where the species is now regular in summer in small numbers, as many as 15 were seen at single locations. Farther west were birds in Ohio, Kentucky, Tennessee, southern Illinois, and Arkansas, and birds are still appearing at new sites.  

Wood Storks also showed up north of their usual range in the southeastern states, although not in such large numbers. Single birds in Michigan and Wisconsin have been the farthest afield so far, but there have been at least three in New York and two in Ohio, others throughout Maryland, Virginia, Kentucky, southern Illinois, and Missouri, plus more than usual inland in the Carolinas and elsewhere in the southeast. Adding to the overall movement have been a healthy handful of White Ibises as far north as Nova Scotia, Massachusetts, Pennsylvania, and Ohio.  

Clearly it has been an unusual year for southeastern wading birds to wander far north. But why?  

When birds show up outside their normal range, people often assume that they were carried there by storms or driven out of their usual haunts by unfavorable conditions. Sometimes that's true. But these waders didn’t ride any storm winds, and while conditions in the South affected them, it wasn't in the ways we might expect. 

Let’s look at the Roseate Spoonbill. In the United States, this species breeds mainly in coastal Texas and southwestern Louisiana (probably more than 4,000 pairs altogether) and in southern Florida (more than 1,000 pairs). I believe the northward push this summer was mostly from Florida. That’s partly based on distribution—the strays were concentrated near the Atlantic seaboard—and partly based on timing. Spoonbills in Florida generally nest earlier than those in Louisiana and Texas, so their young may be independent by early summer; this year, spoonbills started showing up north of normal by late June.  

And essentially all of these wandering spoonbills were young birds. I looked at dozens of photos from this year’s sightings in the northeast, and every single photo showed a juvenile: pale pink and with a white, feathered head, not the naked greenish head of the adult.  
 

It’s normal for young Roseate Spoonbills to move north during their first summer. There’s evidence that some from Cuba may move north into Florida, and some from Mexican colonies move north into Texas. And young spoonbills from the Florida colonies move north regularly also. This year, as in 2018—the last time many spoonbills wandered to the northeast—the breeding season apparently was very successful, producing a bumper crop of youngsters. Higher numbers increase the odds that some will travel farther than usual, and increase the chance that birders will find a few of them.  

Wood Stork is another bird that may move north after the breeding season. This is most apparent in Texas, where storks appear every summer, moving north from colonies in Mexico. In the Southeast—where storks breed mainly in Florida, but also in eastern Georgia and South Carolina—some birds also move north in summer. Young birds tend to be the ones that move farthest. As with the spoonbills, it appears that most or all of the Wood Storks showing up in the northeast this year were juveniles, with yellow bills, not the blackish bills of adults. So at least some of the stork colonies must have had good breeding success this year, producing more potential strays.  

High numbers of young spoonbills, storks, and other waders in southern wetlands might also lead to more competition, giving some individuals more incentive to keep moving. And since water levels reportedly were too high for easy foraging in some southern areas, all the ingredients were in place for a northward invasion, to the delight of thousands of birders who got to see these rare and wonderful birds in unusual surroundings. 

Question: I’ve heard that fall is the toughest time of year for bird ID. Would you agree?

KK: Many birds wear their brightest color patterns for the breeding season. Those hues are meant to impress each other, not us, but they do make them easier to recognize in spring and early summer. In fall and winter, many of those same birds show more muted patterns. But in my experience, the most challenging season for bird ID is in late summer, in that transition between breeding season and fall migration.  

There are specific reasons why birds are hard to identify in late summer, and most of those reasons involve the limitations of feathers.  

Feathers are amazing structures, lightweight and strong, but they do wear out and have to be replaced regularly. As individual feathers are becoming more worn, their colors may fade and their edges wear away. That can change even some of the key field marks we use to identify species.  

For example, the wing bars shown by many songbirds are made up of contrasting pale tips on series of dark covert feathers. Over time those pale tips start to wear away, and the wing bars become narrower or even disappear completely. So in spring, we can tell Eastern Wood-Pewee from Eastern Phoebe at a glance because the pewee has wing bars and the phoebe doesn’t. By the end of summer, the wing bars on the adult pewee may be completely gone.  

Other aspects of appearance change as well. A Song Sparrow or a female House Finch in fresh plumage has clean, sharply defined brown stripes. Months later, when the plumage is in worn condition, those stripes may look drab or obscure.  

Fortunately for the birds (and for birders looking at them), those worn and faded feathers eventually will be replaced in the next molt. Old feathers drop out, a few at a time, as new ones grow in their place. Molt is a very orderly process, but birds going through it can look incredibly messy with their hodgepodge of old, new, and growing feathers. Some species change dramatically with the molt: For example, a male Scarlet Tanager in late summer molts from bright red to dull olive-green body plumage, looking like a patchwork of colors for a few weeks. Others don’t change color, but still look oddly patchy with a mix of fresh and worn feathers.  

There are variations among species in the timing of molt, but a complete molt after the breeding season and before southward migration is fairly typical. So many birds look their worst—either drab and worn, or splotchy and changing—during late summer.  

This is also a season when many young birds are independent of their parents but still wearing their juvenile plumage, and juveniles often look strikingly different from adults. A juvenile American Robin, for example, has a spotted chest and big pale spots on the back. A juvenile European Starling is drab gray-brown all over, without the glossy black of adults. A juvenile Caspian Tern has black chevrons all over the back and wings, where adults are plain gray. Most birds (especially among songbirds) don’t stay in juvenile plumage very long, and when they start to molt into their first-winter plumages, they also display patchy combinations of markings—adding to the challenge for birders trying to identify them.  

If looks can be so deceiving in late summer, what about sounds? What about birding by ear? Unfortunately, the news is no better there. Birds tend to be quiet then, giving only simple calls rather than their more distinctive songs. And juveniles of many have callnotes that are very different from any sound made by adults of their species. So the soundscape of late summer can be just as confusing as the visual aspect of birding.  

So if you feel like you’ve been having trouble recognizing birds lately, take heart. Those messy molts will be winding down, those juveniles will grow up, and birding will be a little less confusing soon. And if you really like a challenge, you can plan to take on the tough IDs of late summer next year!  

Have a bird or birding question for Kenn? Email it to audubonmagazine@audubon.org.