Thursday, May 24, 2012

Searching for Ceruleans on the Roanoke


The Cerulean Warbler is a special bird.  Not only is it the only member of the huge wood-warbler family that is entirely blue and white, but it also has the tragic distinction of being one of the most rapidly declining neotropical migrant songbirds. On average the population shrinks 3 percent each year and has been doing so for decades.  It isn’t entirely understood why the species is struggling so, but the downhill trajectory combined with a low population density has earned it a spot on the IUCN’s endangered species list where it carries the label, “Vulnerable.”
Because Ceruleans nest in emergent trees in mature forest, they are nearly impossible to spot without first being heard. To get at this bird typically requires a special trip to a special known breeding location during the late spring when the males proclaim their presence with a buzzy song that sputters like a tiny gas motor trying to start.  Since ~99.9% of Cerlueans breed in the mountains, that’s where nearly everyone goes to add this special bird to a life, state or year list.

What we set out to do was find that remnant 0.1% of the population that somehow persists miles from all its relatives in a completely different physiographic region in riparian forest along the Roanoke River in the coastal plain of North Carolina.  

The team -- photo by Ken Hackney


Paul Taillie, Natalia Ocampo-Penuela, Mark Kosiewski, Nick Flanders, and I paddling a 15-mile stretch of river going downstream from Weldon, listening intently, hoping to pick out that Cerulean song.

Birding by kayak
We had perfect weather—clear skies and highs around 75—and perfect timing.  We were late enough to avoid fishing boats (we saw two all day) and early enough to beat the mosquitos (my count was one individual for the weekend).  And the river was flowing nicely, so that in the early hours of the morning when the birding was best, we scarcely had to paddle, but would just drift and listen.  

And the river was gorgeous and fantastic for birds.  At any given time two or more Bald Eagles were typically in view.
Bald Eagle
And Prothonotary Warbler was among the most abundant species of the day.  
Prothonotary Warbler
 This Prothonotary nestling enjoys a spectacular view of the Roanoke from its dead tree trunk penthouse (penthole?). 
Prothonotary Nestling
We found 15 warbler species on the day.  It was a little late for migrants and we detected only two: Blackpoll and Yellow, but we recorded 10 singing males of each of two rather secretive and rare breeders, Swainson’s and Kentucky, and got great looks at both.
Kentucky Warbler
And yes, we found our Cerulean Warblers…six males singing away, perhaps hoping to lure in a female from what must be a severely limited supply.  We beached our boats and clambered up the steep bank to try to spot one…
!!
We were thrilled to see our first of 3 seen Cerlueans on the day, but what was shocking was the trashed habitat where this one had decided to stake out its territory.

Prime Cerulean Warbler habitat?
While there were some tall Tulip Poplars (a species they tend to prefer), the forest cover was fragmented by little clear-cuts. Even where the canopy was mostly intact there was evidence of active selective logging.  We saw stumps and freshly downed tree crowns.   

Singing
Sadly this bird may be singing in vain.  Even if he is able to successfully breed in his fragment this year, will there be anything for him in 2013?  Indeed the prospects for this tiny population are grim (even more so than they are for the species as a whole).  

Were the Roanoke Ceruleans, with their isolation, given thousands of years to breed and respond to selective pressures, they might genetically drift to a novel subspecific identity.  But I’m not sure if this population will make it through the current century. 

One of North Carolina’s preeminent birders and naturalists, Harry LeGrand, recently reported zero Ceruleans in at least 12-15 trips to the Roanoke this spring (all working on foot, essentially just in Halifax and Northampton).  He concluded that Ceruleans are "...in considerable decline here."

The good news is that there are large swaths of Roanoke riparian corridor that are protected (i.e. by the nature Conservancy), though I’m not sure how well they correspond with these Ceruleans’ Alamo just south of Weldon. And the problem may very well be with wintering habitat, or something unrelated to the state of the forest buffer along the Roanoke.

Of course, we were having far too much fun to worry too much about the birds’ fate.  With the stream flowing well we made it to the Tillery camping platform (reserved through Roanoke RiverPartners) before 3pm, leaving plenty of time to relax, have a swim, and fish.

Camping on the Roanoke
And it was a spectacular flawless weekend.  We ended up with 90 or so species as a group.  Other highlinghts included one Scarlet Tanager, a singing Horned Lark, a singing Grasshopper Sparrow, Loggerhead Shrikes, a Yellow-crowned Night-Heron, and a stop by Sylvan Heights Waterfowl Park to see the menagerie before heading back to the Triangle on Sunday.

So I would highly recommend having a paddle on the Roanoke. And if you hope to find Cerulean Warblers away from the mountains, I would recommend planning your trip soon!

4 comments:

  1. Looks like you folks had a great trip and we'd love to stay in the loop on any trips along the Roanoke that you take. We'd love to link to your post so our paddlers can learn more about birding and paddling. If you have any stories that you can share on the stretch from Buggs Island to Beechwood Flats or the lower Staunton River/Banister River or the Staunton River please send me a link.

    Best,
    scott www.upperreach.org

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    1. Hi Scott,
      Yes, please link my post to anyone who may be interested. This was my first trip on the Roanoke, but we had so much fun I suspect my second won't be far off!
      I'm unfamiliar with the locations you mention, but your website looks great.

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  2. Looks like a great trip. I very much envy your Warblers, although I was lucky to see some Ceruleans several years ago up in New York state.

    Kayaking seems like a great way to go birding, especially to get some great looks at Kingfishers. Did any of those daring divers show up?

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    1. Hi Laurence,
      Half the point of writing this blog is to try to inspire envy =p... so I guess it's a success!
      I was actually surprised at the scarcity of kingfishers...especially given the abundance of fish and other piscivores. I think we only had a one or two on the day.
      I've found much greater densities while kayaking on rivers in N. Vermont.

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