Rare Itinerant Breeders: How Researchers Discovered the Woodcock’s Unique Breeding Strategy

GPS monitoring reveals American woodcock re-nesting actions throughout the Atlantic Flyway

On this episode, AJ and Gabby discuss with Colby Slezak, a latest PhD graduate from the College of Rhode Island, a few stunning breakthrough in American woodcock ecology: proof that feminine woodcock could be itinerant breeders.

Colby explains how new GPS monitoring expertise, mixed with on-the-ground nest checks by way of the Jap Woodcock Migration Analysis Cooperative, helped affirm a conduct that had lengthy been suspected however not often documented. When nests fail, some feminine woodcock will journey lengthy distances and try to nest once more elsewhere, generally a number of instances in a single spring.

We unpack why woodcock have such an prolonged breeding season, what low nest success appears to be like like on the bottom, and the way constraints like GPS tag dimension and battery life form what researchers can study breeding ecology. Colby additionally displays on the second he and his colleagues realized their information supported this long-standing idea, an surprising discovery that reshaped how researchers perceive woodcock breeding conduct.

The dialog then shifts to Colby’s temporary time with the U.S. Fish and Wildlife Service and what federal workforce reductions and buyouts might imply for conservation capability, long-term partnerships, and the institutional data behind migratory chicken analysis.

To be taught extra in regards to the Jap Woodcock Migration Analysis Cooperative, go to woodcockmigration.org.

Podcast Episode Transcript

AJ: When most feminine recreation birds expertise a nest failure, they may attempt to nest once more a number of extra instances. Trying to renest after experiencing a nest failure isn’t unusual. Nevertheless, woodcock are doing one thing totally different—they really nest and migrate on the similar time, and might even construct a number of nests in a single spring. For instance, if one nest fails, they may proceed north after which nest once more. 

Gabby: This can be a very uncommon breeding technique referred to as “itinerant breeding.” In line with the College of Rhode Island, lower than 0.1%, or solely a few dozen species of birds use this breeding technique. Even crazier is that they may journey wherever between 500 to 1,000 miles between nests.

AJ: Itinerant breeding is outlined as nesting whereas migrating within the spring, so woodcock hold transferring north and making an attempt to nest. That’s totally different from a chicken making an attempt to renest in a basic location, like a duck making an attempt to maneuver to a different close by wetland. Itinerant breeding may imply that birds may increase multiple profitable brood, nonetheless, latest analysis doesn’t show that that is the case with woodcock, however units up some proof that they may.

Gabby: Solely inside the previous couple of years have researchers found the truth that woodcock are itinerant breeders. Different shorebirds in North America solely breed after migration is full, they usually have very sturdy web site constancy associated to breeding grounds, that means they all the time breed in the identical basic space. An absence of web site constancy is exclusive to woodcock. 

AJ: In relation to landmark moments in ornithological analysis, that is considered one of them. In actual fact, the analysis carried out to make this discovery is now thought-about the gold commonplace for documenting itinerant breeding conduct. As for those who wanted one more reason to consider that woodcock are a particular chicken, right here it’s.

Gabby: AJ and I talked to Colby Slezak, a latest PhD graduate from the College of Rhode Island, to be taught extra about this scientific breakthrough.

“Though a good friend some few years in the past advised me that he had seen an American Woodcock with small younger, about twenty-five miles from right here on the Satilla River, I’ve discovered the chicken so uncommon, even throughout winter, that I had about determined that he was mistaken. I used to be due to this fact each shocked and happy on the morning of March 9, 1908, to flush a chicken from a set of 4 eggs whereas driving by way of a thicket of bushes about three toes excessive in a slightly low place on the sting of a swamp. I used to be driving slowly on the time, making an attempt to establish a small chicken, and my horse’s toes have been nearly within the nest earlier than the chicken give up it, rose above the bushes and settled down once more about twenty toes away. The nest was of leaves and a bit of pine straw, and I discovered that incubation would have been over in a number of days, however managed to save lots of the eggs. The nest was about 4 miles from Saint Marys, Georgia, and the Florida line, which I consider is probably the most southerly breeding document for the chicken. Have solely seen one different chicken this 12 months.” — Isaac F. Arnow, The Auk, April 1908.

AJ: For over a century, observations like this raised questions nobody may reply. When Isaac Arnow collected these 4 woodcock eggs close to the Florida-Georgia line again in 1908, little did he know that there was an opportunity the feminine he flushed would relocate farther north and try to nest once more. In actual fact, nobody may’ve even guessed that if it weren’t for the undertaking that Colby Slezak contributed to throughout his PhD analysis.

Colby Slezak: So my title is Colby Slezak. I completed my PhD on the College of Rhode Island this previous August 2024, and I used to be learning the habitat choice and breeding ecology of American woodcock in Rhode Island and the Atlantic Flyway. We discovered that woodcock are itinerant breeders, which primarily signifies that they may nest after which migrate between their nesting makes an attempt if that nest fails.

So most birds will return to comparable breeding grounds annually. There’s this benefit to going again to a spot—you realize the predators there, you realize the place the meals sources are—and so you’ve got this benefit. However woodcock are extra versatile, they usually can transfer between their nesting makes an attempt in the event that they fail.

Gabby: One other chicken that’s recognized to be an itinerant breeder is the phainopepla. It’s believed that this chicken, which resembles a completely black northern cardinal, follows seasonal mistletoe abundance inside its vary in southwestern North America. Nevertheless, the American woodcock is the primary chicken that scientists have direct proof of itinerant breeding as a result of they’ve been capable of monitor particular person feminine birds throughout their spring migration. And that is precisely what Colby was engaged on whereas he was incomes his PhD.

Colby Slezak: A brand new monitoring expertise is absolutely what’s allowed us to determine this itinerant breeding thriller with American woodcock. So we have been utilizing these Low Tech GPS transmitters—Low Tech is the corporate, not the standard of the transmitter.

We have been capable of connect these small tags and really monitor the migratory actions for a lot of tagged woodcock over the previous 5 years. And that’s a part of the Jap Woodcock Migration Analysis Cooperative that’s being led by Eric Blomberg on the College of Maine. Eric has a bunch of grad college students, in addition to my advisor, Scott McWilliams, and I used to be capable of monitor females.

So one of many issues I needed to do as a part of my PhD was attempt to find nests all through the Atlantic Flyway. Initially, I used to be simply centered on making an attempt to determine the place these birds are nesting outdoors of Rhode Island, as a result of we had our native research in Rhode Island, however I needed to know what was occurring at a bigger scale.

I used to be sending folks out when it appeared just like the GPS actions have been suggesting a nesting try—so actually small actions between subsequent GPS factors. These tags have been taking a few hundred factors per spring, and so then I might ship somebody out, one of many biologists that was cooperating on our Flyway undertaking, and they’d attempt to find the nest for me.

Being utterly sincere, I wasn’t as impressed as I may have been till my advisor and Eric Blomberg had appeared on the information, they usually have been like, “Wow, that is one thing actually loopy they’d by no means seen earlier than.” Then I acquired all enthusiastic about it. I began trying into itinerant breeding, and there are various species that this has been suspected in, however this was actually the primary direct proof of somebody truly going out and discovering a nest of a tagged chicken within the south, after which discovering one other nest in one other location farther north that very same spring.

I used to be principally tagging females and looking for nests so I may have a look at habitat associations, however we ended up discovering this actually cool conduct that we had not got down to search for.

Essentially the most thrilling factor was that we discovered one thing cooler than what we anticipated.

AJ: So Colby talked about the Jap Woodcock Migration Analysis Cooperative, or the EWMRC. This cooperative is a global, multi-state collaboration undertaking between universities, nonprofits, and wildlife companies. Its aim is to particularly be taught as a lot in regards to the woodcock migration in North America’s japanese flyway as potential.

Gabby: The EWMRC has tagged over 500 woodcock with GPS transmitters. They need to be taught extra in regards to the particular forms of habitats utilized by migrating woodcock, what time migration begins and ends, confirm that male actions line up with singing chicken surveys every spring, calculate survival charges, and way more. 

AJ: Its web site is woodcockmigration.org, and if you wish to test it out, you may comply with together with the woodcock migration, study their analysis targets, and help their analysis.

“Males set up and preserve breeding territories referred to as ‘singing grounds’ on previous fields or forest openings and carry out crepuscular aerial shows for the aim of attracting females for copulation. The show begins after the male alights in an open space of his singing floor. It’s initiated on the bottom with the male strolling round in a small space (often only some sq. meters) uttering a loud, nasal, insect-like sound described as a ‘peent’ roughly each 20 seconds. Previous every peent is a delicate gulp or ‘tuko’ that may be heard solely as much as 20 to 30 m. This floor show might final 5 minutes or extra, though durations of roughly 2 minutes are extra widespread. After peenting ceases, the chicken flushes and begins a sluggish spiraling climb to a top of 60 to 150 m. The realm encompassed by the spiral is roughly 2.7 acres. In the course of the ascent there’s a fixed twittering sound made by the wings. The descent is way faster than the ascent and follows extra of a zigzag sample than a spiral. In the course of the descent, the twittering ceases and is changed by a sequence of chirps that seems like a ‘liquid warble.’ At 15 to 30 meters, this sound stops, and the rest of the descent is silent.” – Division of Protection Pure Sources Program: American Woodcock (Scolopax minor), Part 4.1.2. US Military Corps of Engineers Wildlife Sources Administration Guide. April 1, 1989.

AJ: Though exhausting science hasn’t all the time been there to help our suspicions, hunters and wildlife managers have suspected that woodcock is perhaps itinerant breeders earlier than. And till now, nobody may comply with a single chicken by way of a number of nesting makes an attempt.

Colby Slezak: So woodcock will nest wherever from January into July in some instances, which is absolutely uncommon for birds.

But in addition, within the Nineteen Eighties, there’s some anecdotal proof within the literature from Eugene Wiley and Keith Cozy. They have been learning American woodcock down in Alabama, chick survival, they usually banded this feminine woodcock with chicks that was later shot that fall in Michigan. So it type of puzzled them, as a result of how did this woodcock that was elevating chicks down in Alabama find yourself in Michigan that fall?

And so on the time, they thought that perhaps woodcock have been having two broods per 12 months. So perhaps they have been having a brood in Alabama, then going north and having one other brood once more, which is why that feminine was there and acquired shot there by a hunter. However now we all know that perhaps that woodcock feminine had a brood, it failed, the chicks acquired eaten, after which she most likely migrated north and doubtlessly nested once more, which is the way it acquired shot there.

So you should use these little items of proof, and it’s like this lengthy thriller that we solved with these newer tags.

Gabby: American woodcock are recognized for his or her abnormally lengthy breeding season. A few of Colby’s analysis from Rhode Island confirmed that the speed of nest success, or nests that fledged at the least one chick, was about 10%. Equally, his analysis additionally confirmed that some feminine woodcock nest as much as 6 instances every spring. Whereas that analysis isn’t reflective of the complete japanese woodcock inhabitants, it does recommend that maybe it takes a number of makes an attempt for woodcock to efficiently increase a brood. 

AJ: What I discovered probably the most attention-grabbing is simply how a lot distance one feminine woodcock can journey between every nest try. Say a feminine woodcock resides in Florida in the beginning of the breeding season. If that chicken makes an attempt to nest in Florida and the nest fails for no matter purpose, she may journey lots of of miles north earlier than trying to lift one other brood. She may expertise one other nesting failure in North Carolina, then New York, and in the end land in southeastern Canada and nest once more.

Gabby: At this level, this GPS analysis is proscribed by the battery life of every tag. Each transmitter planted on a chicken can solely document about 100 GPS factors, after which level the battery dies. As a result of transmitters should weigh 3% or much less of a chicken’s physique weight, those that woodcock put on are very small, and it takes plenty of battery energy to ship information factors to a satellite tv for pc.

AJ: Nevertheless, if scientists and engineers create an ultralight battery that may last more, folks like Colby and the EWMRC can begin to acquire much more long run information, issues like whether or not females proceed north after her chicks fledge, their day by day actions, how typically particular person birds revisit the identical potential nesting places 12 months after 12 months, and even when woodcock ever increase two broods in a single 12 months.

Gabby: Let’s deliver it again to that low nesting success charge for a minute. What precisely is contributing to nesting failures? Is it climate occasions, predation, meals availability, or one thing else?

AJ: In line with Colby, in Rhode Island predation is the primary factor negatively impacting nesting success. 

Colby Slezak: We didn’t discover any nests, out of about 50, that appeared like they’d failed from something associated to climate occasions or meals or something like that.

All of them appeared to have been predated, based mostly on proof from us monitoring them and searching on the eggshells. Most of them have been utterly crushed or gone, so doubtless mesopredators getting at these nests. Woodcock usually nest on forest edges, so often at that interface between forest and area—that’s an excellent hall for mesocarnivores to really transfer alongside.

And so we expect that’s a part of the issue, at the least in Rhode Island, with the low nest success, is these exhausting edges the place woodcock are nesting.

AJ: The Audubon Society has printed one idea as to why woodcock are itinerant breeders:

“One doubtless clarification has to do with the tough realities of the American Woodcock’s reproductive timing: Among the many earliest North American species to breed every spring, some people start nesting as early as January and journey northward simply as winter snows are melting, exposing the birds to nasty climate that may result in nest failure. As floor nesters, their eggs are additionally weak to predators. By itinerant breeding, females can nest a number of instances with a number of males—the birds don’t type pair bonds—for a greater probability at success.”

Gabby: One thing that Dr. Eric Blomberg’s woodcock analysis has proven is the distinction between how female and male woodcock migrate. However why males sing whereas migrating has been a thriller. Colby thinks it might must do with their breeding technique.

Colby Slezak: One other thriller within the woodcock literature is why males sing alongside their migration routes. Whenever you observe males within the spring, as early as January, you’ll hear males singing down within the South. Throughout that point, researchers have famous that these birds are migrating, as a result of they’ll be singing there one evening after which gone the subsequent.

What we expect is going on there—though lots of people speculated that perhaps these males have been training earlier than they acquired to their breeding grounds within the spring—is that these males are most likely opportunistically breeding with females who’re additionally passing by way of.

As a result of if the females are migrating and nesting alongside the way in which, the males are most likely going to take breeding alternatives on their strategy to the breeding grounds. We do assume that males have a extra set migratory path. So from the Flyway Cooperative, among the tags have been scheduled to take information over multiple spring migration, and we’ve been capable of finding that males do comply with, in some instances, an identical migratory path between breeding seasons, they usually do appear to have extra of a closing cease.

Extra doubtless than not, the males are most likely simply breeding as they’ll with females which might be passing by way of—doing an identical technique to the females—however then ending up at a extra stationary breeding floor.

AJ: On the similar time we’re studying extra about woodcock than ever earlier than, the folks and programs that made that discovery potential are beneath stress.

Gabby: Researchers are fixing mysteries about woodcock which have lingered for over a century, and they’re doing it at a second when the way forward for that type of analysis is unsure. That stress grew to become actual in 2025, when Colby took a brand new federal job in Utah and the Trump administration began providing federal workers buyouts. 

AJ: The very individuals who spend a lot time researching birds discovered themselves at a crossroads: take the buyout, or danger getting reduce in federal workforce reductions. 

Colby Slezak: I began with the US Fish and Wildlife Service immediately. After ending my PhD in August, I moved to Salt Lake Metropolis to work as a fish and wildlife biologist, engaged on endangered species and migratory chicken coverage in Utah. Then, with the brand new administration, many individuals working in coverage positions and in pure sources generally have been confronted with this actually exhausting resolution to both take the federal buyout or danger getting reduce in a discount in power.

So I used to be suggested to—and I feel it was the most suitable choice for me, at the least—to take the federal buyout. They stunning a lot gave us severance pay to depart our jobs and people roles. And now the federal government has been just lately rolling out these reductions in power, so individuals are shedding their jobs or are vulnerable to shedding their jobs, particularly in conservation.

Many of those federal workers are actually devoted to their jobs and have been working with states and nonprofits for a very long time, in some instances. So that you’re shedding plenty of these folks out of the blue, and these partnerships will simply go away in some instances with out a lot switch of data. So it’s placing folks beneath plenty of stress.

And fairly truthfully, I feel it’s making the federal government extra inefficient in the way it’s working with these new directives. With a lot power improvement on the Trump administration’s agenda, I feel it places plenty of that crucial habitat in danger. On the East Coast, we now have so many nationwide wildlife refuges and migratory chicken biologists working to preserve these species and these actually necessary crucial stopover websites for species like American woodcock in these extremely developed areas.

If we lose these, it is going to have cascading results for lots of those totally different species which might be already in decline. So not solely are you going to lose that land that these wildlife want, you’re shedding plenty of institutional data from these biologists who’re now not in these roles.

However we hope that we don’t get insurance policies on that administration’s agenda which might be extra centered on improvement than precise conservation of species, as a result of that might actually be the downfall for a few of these extra imperiled species which might be on the market.

Until you’ve got heard it your self chances are you’ll discover it exhausting to consider that the woodcock, that long-billed, bug-eyed eater of earthworms, can sing a music as candy as a nightingale’s. But a singer he’s, and anybody who lives away from town nearly wherever within the northeastern quarter of the nation can hear him trill any night within the early spring when he performs his antic mating dance. Look—no, pay attention—for him in a grassy clearing exhausting by a fringe of alder or aspen, simply as the sunshine begins to fade…he fills the air with joyful chirpings, an aria of sentimental, liquid, musical notes that appear to gush out of him as an expression of utter ecstasy, and as candy and melodic as any chicken music man has ever heard. —H.G. Tapply, “The Tune of the Woodcock,” The Better of Area and Stream, April 1972.

AJ: What reads like pure poetry right here is definitely an account of some of the uncommon breeding shows in North American birds. And whereas Tapply may describe what he heard and noticed intimately, we’re nonetheless, even at present, making an attempt to completely perceive what drives that conduct.

Gabby: It’s superb to me that we’re nonetheless studying new issues in regards to the American woodcock. The itinerant breeding discovery is a serious step ahead in understanding how this chicken truly reproduces in any respect. Equally, it’s a testomony to how adaptable this chicken actually is. 

Colby Slezak: I’m simply, I assume, actually grateful to all of the woodcock researchers on the market who’ve given us this data. I had talked about earlier these extra fundamental ecological questions that they’ve requested, and simply the questions they pose of their literature and analysis papers that they’ve written that made this analysis potential, but additionally allowed us to develop upon and reply these long-term questions.

As a result of if it wasn’t for his or her analysis, we actually wouldn’t have been capable of uncover this or notice simply how uncommon it’s amongst birds and issues like that. I’m simply actually grateful to all these folks on the market who’ve put within the exhausting work learning woodcock through the years.

AJ: Their potential to journey to locations they’ve by no means been earlier than and experiment with nest success could be very distinctive. Given the state of earth’s local weather, it provides me hope to assume that the woodcock could possibly be a species that thrives for many years to return. 

Gabby: However whether or not we’re capable of proceed researching the adaptability of the American woodcock will rely upon if we proceed to put money into the folks learning it. 

Colby Slezak: I feel American woodcock are simply tremendous quirky. They’re actually strange-looking. I feel their dances are simply actually cool to observe—for those who deliver out anybody to observe a male woodcock show within the spring, they’ll’t assist however smile.

And so I acquired to expertise that many instances all through this analysis, simply bringing technicians and undergraduates out within the area with me. It was actually thrilling to see their pleasure with these birds.

And for those who ever get to carry a woodcock chick, it’s fairly superb. They’re simply in regards to the cutest, weirdest-looking birds you’ll ever see.

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