The Nidification of San Vito

Golden-hooded Tanager in nest. (Photo: Harry Hull)

This will sound a little strange to North Americans: “Winter’s in the air and nests are everywhere“! We are two months into our rainy season, aka tropical winter, and that puts us deep into the nesting season. When we stand still and watch, we find nests everywhere: under the eaves, high in the trees, low down in shrubs, under plant leaves, in tree trunk cavities and even on fence posts.

Common Potoo with its egg on a fence post. (Photo by Barbara Keeler Barton)

Because the nesting season started back in April we see now, in early June, fledglings chasing their parents begging to be fed. In a short walk this morning, I counted at least six young birds pestering adults: Tropical Kingbird, Cherrie’s Tanager, Variable Seedeater, Bronzed Cowbird peeping at a surrogate parent Rufous-collared Sparrow, Lesser Elaenia and Silver-throated Tanager. By the time they get to this stage, you can almost see the parent birds swiping their foreheads with the side of their wings thinking: will these young birds EVER learn to feed themselves?

A few days ago, an adult Blue-crowned Motmot led two young birds to our banana-papaya feeder and sat there alternatively stuffing pieces of fruit into the gaping bills of each of its offspring. This was, of course, a truly  thrilling ‘National Geo’ moment with my camera nowhere nearby.

Then, too, I recently caught a Fiery-billed Aracari peering into a large shrub outside our front door where a pair of Cherrie’s Tanagers are going for a second nesting. No doubt it was looking for food for its own young but it’s hard not to root for the littler guys.

Golden-hooded Tanager nestlings, 11 days old. (Photo by Alison Olivieri)

We are puzzling over what happened to two nestling Golden-hooded Tanagers that seemed ultra-secure in a hanging basket on our porch. The adults chose a safe-looking spot where the voracious local squirrels might overlook them, but they disappeared in mid-day while we had a little pool party with friends. They were 15 days old and didn’t seem big enough or strong enough to fledge. Maybe a snake wound its way up there or the squirrels managed to grapple up the beams after all.

Squirrel Cuckoo nest. (Photo by Aracelly Barrantes)

Predators and other dangers are everywhere here. First-time nesters sometimes build flimsy nests without adequate protection from heavy rains that are subsequently washed away. Hummingbirds in the ‘hermit’ group build nests hanging from the underside of large maranta or heliconia leaves that can be toppled over in strong winds or unrelenting rain storms. Trees fall over regularly at this time of year and raptors, like the Swallow-tailed Kites that come from South America to breed here, are constantly on the hunt. This is to say nothing about the many opossums, raccoons, weasels and snakes that patrol at night. Or humans wielding weed-whackers, machetes and chainsaws.

Because danger comes from all directions and at all times, birds must take counter-measures. My favorite is the swaying flycatcher nest attached to a wispy branch in a tall tree with the entrance hole on the side or at the bottom. It is an absolute marvel and one wonders how that clever pendant, retort or ovoid-shaped blueprint got started. No predator weighing more than a few ounces could ever get inside. We found a beauty at Finca Cantaros several weeks ago, painstakingly constructed by a Yellow-olive Flycatcher. In the meantime: go outside! Look around! It’s amazing what you will see.

Yellow-olive Flycatcher entering nest from below. (Photo by Harry Hull)

CR Banders Meeting 9 April 2012

InBio Parque, Santo Domingo de Heredia

The movers and shakers behind the Costa Rican Bird Banding Network hosted a day-long meeting at InBio Parque in Santo Domingo de Heredia on April 9 that started with an early morning Banding Demonstration led by Jorge Leiton who has helped at several of our mist netting project sessions in San Vito.

Attendees at Banders Conference April 9, 2012 (Photo: Sara Estrada)

Conference speakers delivered presentations on up-to-date research being conducted at several sites in Costa Rica, information on new tools and other innovations for bird monitoring projects, international capacity building provided by the North American Banding Council’s certification and training programs, a summary of one of Stanford University’s many long-term projects and information on the Banding Network and the new Costa Rican Bird Observatories. Additionally a LaMNA (Landbird Monitoring of North America) Data Analysis Workshop was held in the afternoon.

Jared Wolfe, a PhD candidate at Louisiana State University presented a paper, currently in review, titled “A Tropical Bird’s Dissimilar Response to Global Climatic Phenomenon in an Uneven Aged Forest.” The data for this paper were gathered at the oldest, continually-run banding station in Costa Rica at Tortuguero National Park on the Caribbean side.

VP Kate Desvenain and Sara Estrada (Photo: Alison Olivieri)

Another research project, from CATIE in Turrialba and presented by Fabrice DeClerck, showed a significantly increased bird population in agricultural landscapes by leaving unpruned the famous ‘living fences’ of Costa Rica, traditionally used to define pasture and agricultural acreage. Researchers at CATIE are teaching environmental education programs for teachers at nearby schools as well as involving the teachers and their students in their research projects.

C. J. Ralph of the USDA Forest Service displayed dazzling migration range maps for Indigo Bunting and Common Nighthawk created from eBird data. They literally made you want to run home to your computer and immediately update your eBird account. After seeing what C.J. was able to show, there is NO EXCUSE not to enter all your sightings and add to this powerful and complex data tool.

The San Vito Bird Club was well represented at the meeting and several members stayed for the afternoon presentation on data analysis that will surely benefit our Avian Monitoring Project.

Thanks to Pablo Elizondo of Partners in Flight and the Costa Rican Bird Observatories for an inspiring conference that provided new insights into bird population dynamics, a forum for exchanging ideas and answering questions, and stimulating new information.

Golden-hooded Tanager nesting

Several weeks ago, Gail Hull spotted Golden-hooded Tanagers building a nest in one of the jaboticaba bushes near Laguna Zoncho at Finca Cántaros, and now, we assume, there are eggs in the nest being brooded. I shot the photos in the slide slow below of the female (?) Golden-hooded Tanager sitting in the nest. Frequently, the bird has its beak open as though panting, so I’m guessing that it was hot or tired. Harry Hull

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