Tag Archives: Observations

(Un)happy Endings

Even for birds, things sometimes don’t go as planned.  In fact, we’ve found that for Rose-Breasted Grosbeaks, life often doesn’t follow its intended course.  None of the Grosbeak nests we’ve found have lasted until the chicks fledged, and many were “popped” (eaten) or abandoned before the eggs even had a chance to hatch.   After six failures, but before we resigned ourselves to the apparent curse of the Pheucticus, we did a little research.  Friesen, Cadman, and MacKay found that only 46% of the Rose-Breasted Grosbeak nests they kept tabs on made it to completion, i. e. 54% of their nests did not yield any fledglings (1999).  Compared to our 0% success rate, 46% was looking pretty good.  However, Dungay, Woods, and Nichols reported a success rate of only 32% (2001).  Consultation of the Birds of North America account revealed that our Grosbeaks’ low success rate may also be a consequence of the fragmented nature of the available habitat.  Despite their preference for fringe habitats, Rose-Breasted Grosbeaks also tend to have a lower nesting success rate in more fragmented habitats.

Taking all this into account, and pushing valiantly through the heartbreak of losing yet another nest, we decided we needed to make darn sure the nest was empty.  We had assumed the happy Grosbeak couple was incubating when one or the other was constantly on the nest, which we first observed on July 2.  This meant that there should have been eggs in the nest.  To check for the presence of eggs, we used a very special piece of equipment: a nest mirror (also known as a mechanic’s mirror).

The basic plan was as follows:

Much more difficult than anticipated!

Operation Nest Mirror

Simple enough, right?  We thought so.  However, we forgot that the nest, although located relatively close to the ground, was also directly over a giant patch of honeysuckle.  After several tries, Hilary eventually managed to hold the mirror in a position that reflected the image of the tragically empty inside of the nest to Emma and me, who were looking on intently with binoculars and a camera.  Although our hard work revealed nothing but an empty nest, we felt we had accomplished something by figuring out how to look inside a nest that was way above our heads.  Hopefully the next time we use our ingenuity to look in a nest, we’ll be greeted by the sight of happy little chicks!

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What Could be Better than Ice Cream?

Two Fridays ago, our research team headed into the field, eagerly anticipating the prospect of Purity ice cream at the Lab of Ornithology’s social that afternoon. Little did we know that we were in for a very different (and as much as we love Purity ice cream), even better, treat.

Opening up what we’ve termed our “nest contents” spreadsheet in Excel, we briefly scanned our timeline to gauge the approximate time of hatching for our only active Scarlet Tanager (Piranga olivacea) nest at the time. The Scarlet Tanager account on BNA (the Birds of North America Online) describes departure from the nest on day 9 or 10 after hatching; by our rough calculations, the fledglings at our nest of focus would either be near the nest, already out and begging for food, or in the nest, close to fluttering out. With that in mind, Jen and I decided to head out for a two-hour nest watch, lugging – just in case – the HDV camera lent to our team by Macaulay.

While Eric and Tim went in search of new nests and juveniles, the two of us settled down in a spot where we could get a clear view of the nest (SCTA5 is notorious for being extremely well-hidden). After focusing the video camera on the delicate, saucer-shaped nest far above our heads, we started the watch. The first 30 minutes or so were much like any other day of nest watching involving parental care of nestlings – one parent at a time arrived to the nest at varying time intervals – the only exception, however, was that within that first half hour at SCTA5, only the male visited the nest.

For a brief (and of course, always exciting!) snapshot of our nest watch that day:

At 10:55 AM, as the parents were out foraging, there was some slight movement on the nest.
At 11:01 AM, the male was singing softly as the female called in the under-story, on a branch remarkably close to the observer – both aspects being atypical for the behavior of a female tanager while foraging for her nestlings.
For the next five minutes, the female gradually moved closer and closer to the forest floor directly below the nest, continuously chck-brrring.
At 11:05 AM, sounds that seemed to be begging calls were heard. The male and female continued to sing and call until suddenly, there was a small flash of a fluffy grey bundle scurrying towards a log.

Yes, indeed – it was a Scarlet Tanager fledging, our first one seen straight out of the nest.

The HDV camera Jen and I had luckily brought out was quickly trained on the fledgling, who was remarkably agile. He was able to make his way across the forest floor fairly quickly and was capable of short, fluttery flights. As Jen and I followed him from one log to another, he eventually tried to move up along a small sapling – an evolutionarily helpful instinct for avoiding predators.

Scarlet Tanager Fledgling

Hello, world!

As we were wholly engrossed in our careful stalking of the fledging, we almost forgot to call Tim and Eric to join us. When they finally arrived, armed with a Marantz audio recorder, an extra battery for the camera, and an additional tape for the video camera, our small but extremely excited fan club for the fledging was complete.

Eric Gulson taking an audio recording of begging calls.

Our team spent the next five hours collecting digital media on the fledging, who finally decided to stay on a thin sapling branch (which oscillated up and down every time the male tanager came in to feed his fledgling, leading to some adjustments with the video camera). In the course of those five hours (time does fly when you have a fledgling to occupy your thoughts), Eric found another young Scarlet Tanager fledgling about 6 meters up a maple. This second fledgling was being fed by the female in the territory, indicative of a rather common practice among parent birds of splitting up feeding duties among their fledged young.

Jen Goforth recording a video of the fledgling.

At the end of the field day, we reluctantly left the SCTA5 territory and headed back to the data trailer with our photos, videos, audio recordings, and of course,  some lasting memories – perhaps not of ice cream, but certainly of a very endearing fledgling.

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Spotlight on: Scarlet Tanager

The Scarlet Tanager (Piranga olivacea) is arguably the bird that led to the conception of this entire project. The story begins with the Piranga tanagers, a genus that also contains familiar North American birds like the Summer (P. rubra) and Western Tanagers (P. ludoviciana) as well as more southerly species like the Flame-colored (P. bidentata) and Rose-throated Tanagers (P. roseogularis). These tanagers were originally classified with…well…the other tanagers, a wide radiation of American birds in the family Thraupidae. Recently, advances in molecular studies have indicated that this is not, in fact, the case. Piranga tanagers are not tanagers at all. According to their molecular make-up and DNA, these birds are actually Cardinalids. The American Ornithologists’ Union has since updated its taxonomy to reflect this change, placing the Scarlet Tanager and its kin alongside the cardinals, buntings, and grosbeaks of the family Cardinalidae. This discovery prompted the realization that, if these birds are so similar at their most basic building-block level, perhaps there are biological and behavioral similarities that had previously gone unnoticed. Thus, the Tompkins County branch of CEFO was born, with the goal of observing and recording the breeding biology of our own local Cardinalids.

Credit: Justin Hite

Tricky taxonomy aside, the Scarlet Tanager is a very impressive bird. They can be found in a wide range of wooded habitats across eastern North America, being replaced by the similar and appropriately-named Western Tanager in the west. They winter in northern South America, but their breeding habitat is the deciduous and mixed forests in the United States and southern Canada. The birds are about 7 inches long, with a greyish bill and feet in all plumages. Adult males have a striking pattern: brilliant red plumage with contrasting black wings and tailfeathers. The female is a dull, inconspicuous olive-green with some yellow and grey mixed in. Immatures and nonbreeding males are similar to females, though nonbreeders possess the black feathers of the breeding season. In their first spring, male tanagers may retain some yellow feathering in patches, while other males have an orange coloration overall. Fledglings often have streaking on their breast and flanks for some time after leaving the nest. The tanager is readily identified by its song, which resembles that of a robin, but with a hoarse, “burry” quality to the phrases. The bird’s “chck-brr” call is a common sound, and a distinctive identifier, in these woods.

Scarlets are birds of the canopy. Even the flashy males can be challenging to pick out as they move about the foliage in the treetops, though they can be spotted when they come into the opening or move closer to the ground. They forage as they go, gleaning insects and spiders from the leaves or snagging aerial arthropods such as dragonflies. They are also known to eat some plant matter. They usually place their nest towards the end of a branch with a clear view of the surrounding area, building a loose-looking cup of twigs and other plant materials. They seem to prefer deciduous trees, but one of our most productive nests was located in a conifer along the trail! Clutch size ranges from 1-6 greenish blue eggs with brownish speckling. Incubation lasts around 2 weeks, and the chicks themselves fledge within 9-11 days after hatching.

At our study site, we found a surprising number of Scarlet Tanager territories spread across the woods. We were able to locate and monitor 7 individual nests over the course of our field season. The birds’ distinctive vocalizations made them easy to locate, and they proved to be very cooperative subjects. The tanagers seemed to adjust readily to our presence, carrying on with their daily activities at the nest with us watching intently. Some individuals even seemed interested in us, with the pairs at nests 3 and 4 often coming down out of the canopy to watch the nest-watchers from nearby branches. We were able to observe a wide range of behaviors related to site selection, nest building, raising the eggs and chicks, and territory defense from rivals and predators. They were also much more successful than our observed grosbeak pairs at making successful nesting attempts where the chicks survived to fledge, but more on that later!

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