On 28 March the first egg was laid. (Image sourced online at http://www.allaboutbirds.org/page.aspx?pid=2433.)

Just this morning, I received an e-mail from The Cornell Lab of Ornithology announcing a new Great Blue Heron nest cam (they also have a Red-tailed Hawk nest cam this season). The nest is on the property at the Lab's "Sapsucker Woods" campus. In addition to point-blank nest views, the nest cam provides an audio feed so you can hear various other birds calling and singing in the background. It should be fun trying to pick out warbler songs over the next few weeks.

The best feature of the nest cam site is a live chat stream, which allows for a fun exchange among the many folks who are watching. Questions come fast and furious as some of those watching admit to knowing very little about birds. During the 4-5 minutes that I followed the chat stream there were questions/discussions about plumes, incubation, sexing the adults, and a resident Canada Goose named "Sweetie."

The questions and answers about plumes included mention of plume hunting and how that was in part responsible for the formation of the The National Audubon Society. Some chat participants were unaware of the impacts of plume-hunting and how it inspired early bird conservation efforts.

On this day, it's cold and blustery in Ithaca, New York, so the moment-to-moment video and audio provided by the camera are a far cry from scintillating. One of the adults has been standing essentially motionless over a single egg (looks like an over-sized American Robin egg) as the wind ruffles its feathers. During the time that it took me to write this short article, the adult heron has moved just twice. First it turned to face the opposite direction, stepping on the egg briefly as it did so and then, finally, it sat down on the egg.

Finally, after many minutes the adult heron sat down on what had to be one very chilly egg. (Image captured online at http://www.allaboutbirds.org/page.aspx?pid=2433)

Despite the general lack of activity in the nest, the chat remains lively. In addition to feeding our voyeuristic nature, this nest cam fosters a wonderful opportunity for birders and non-birders to share and learn together in real time. Over the next several weeks I will likely be one of many who pop in occasionally to see what the birds are doing and sample what everyone is talking about. I can't wait to see the baby herons and hear their incessant "walla walla walla" vocalizations.

This map shows the April pattern of distribution of Black-throated Gray Warbler eBird reports for all years 1900-2011. (Image sourced online at  http://ebird.org)

On 9 March 2012 a Black-throated Gray Warbler was reported from Bandon State Natural Area on Oregon's south coast. There was modest debate on the local listserv over whether this bird was overwintering or, perhaps, an early northbound migrant. I was in the overwintering camp.

Just a week earlier, I was melding together the Oregon and Washington sections of the Fall 2011 report for North American Birds when I noted that my co-editor, Brad Waggoner, had characterized a November 1st Black-throated Gray at Vancouver, Washington as being "a month tardy."

It's important to note that Brad lives on Puget Sound about 180 miles north of where this bird was seen. Vancouver is just across the Columbia River from Portland, where I live. Since low numbers of Black-throated Grays are still passing through Oregon during the first two weeks of October, I would have described this bird as being about two weeks late.

These discussions, which involved highly experienced birders, demonstrate that each of us has unique notions about the migratory timing of Black-throated Gray Warblers. These perceptions are shaped by where we live and our own set of experiences with this species. 

My experiences with migrant Black-throated Gray Warblers have come primarily from the Willamette Valley in western Oregon. In the southern end of the valley–where I lived from 1984-86 and from 1998-2010–the first northbound Black-throated Grays would appear in during the first few days of April. Skinner Butte in downtown Eugene would almost always yield the earliest sightings for the valley and often for the entire state, in part because it gets daily coverage from late March through May. The first reports Portland (110 miles to the north) would come several days later, usually not until about the 10th of April or later. The fall migration of warblers through Oregon is diffuse and there are rarely weather systems that create noticeable fallouts. Along the outer, coast the southbound "passage" of warblers borders on undetectable. In the interior lowlands, focused efforts along riparian corridors, especially those bordering north-south running waterways will produced small mixed flocks of migrants that usually include a few Black-throated Grays until about 15 October.

Since my ideas about the migratory timing of this species were not the same as other equally experienced observers, I decided to compare my perceptions about Black-throated Grays with the data that one can easily mine from the eBird database. Here's what I found.

January eBird reports of Black-throated Gray Warbler 1900-2012. (Image sourced online at  http://ebird.org)

February eBird reports of Black-throated Gray Warbler 1900-2012. (Image sourced online at  http://ebird.org)

March eBird reports of Black-throated Gray Warbler 1900-2012. (Image sourced online at  http://ebird.org)

At a glance, the three maps above, which show the distribution Black-throated Gray Warbler reports for January, February, and March are remarkably similar. Compare these to the April map at the top of the article, which shows a major influx of Black-throated Grays all along the Pacific Coast during that month.

We can also look at the year-long bar graphs, which offer better resolution of what happens within each month. The bar and line graphs below provide a closer look at the migration timing in Northern California, Oregon, and Washington.

This graphic shows the annual bar and line graphs for just those counties in the northern one-third of California, basically drawing line from Placer on the eastern border (at the elbow of California) west to Mendocino. It illustrates that Black-throated Gray Warblers are reported almost year round, with the spike of spring migrants starting just before 1 April and peaking during the last two weeks of April. (Image sourced online at  http://ebird.org)

The annual bar and line graphs for Oregon shows that Black-throated Gray Warblers are essentially absent from the state November-March. The spike of spring migrants starts right about 1 April and peaks about the first week of May. Note that the number of fall reports remains pretty high into October, with a sharp drop-off after the second week of October. (Image sourced online at  http://ebird.org)

The line graph for Washington is nearly identical in shape to that of Oregon, but it is more compressed. The spring spike in Washington doesn't really kick in until about 15 April, but still peaks right at beginning of May. Note that in Fall the sharp drop-off comes about 1-2 weeks earlier than it does in Oregon. (Image sourced online at  http://ebird.org)

One of things that is exposed in looking at these graphic representations is that the spring migration of Black-throated Gray Warbler is incremental in nature. When we think about migration, we are captivated by those species that make long trans-oceanic crossings and non-stop flights that extend for multiple days. By contrast, the migrations of many passerines involve a more protracted series of short hops. In looking at the bar graphs above, it is apparent that the first influx of northbound Black-throated Gray Warblers Northern California about two weeks or more before they reach Washington. The southern end of the area represented by this set of graphs is approximately 500 miles to the south of the southern border of Washington. If we break down this distance as it relates to the number of days (about 15) between arrival dates at each end of this 500-mile divide, it translates to about 30-40 miles of northbound flight per day. Surely, this is an over-simplification, but the data does suggest that Black-throated Grays are either coming north in a series of short flights or making longer hops and then stopping to rest and feed for multiple days along the way.

In the end, this exploration confirmed my thoughts about what constitutes "early" and "late" in Oregon. More importantly, it demonstrated that the perceptions of my colleagues are equally valid given the experiences one would have living where they live.

Several months ago, this journal published an article entitled Creating a "Social Field Guide." Our mission is to make the BirdFellow Social Field the best place on the web to learn about birds and for our Social Field Guide to be the centerpiece of our online content. Believe it or not, you can contribute. 

This screen grab presents an example of one of our Identification Photo galleries. These images of White-crowned Sparrows come from photographers all over the U.S.

The first step is to create your BirdFellow account, which is free! Once you've created your private online workspace you'll have a place where you can store bird photos, keep lists, and write field report narratives about the birding trips you take. While we encourage folks to engage with the community, we offer customized privacy settings  that allow you select how "public" you want your activities to be. Most folks want to share photos and potentially see their images included in our curated galleries of "Identification Photos."

We constantly "mine" our "Community Photo" galleries–the photos that BirdFellow users share publicly–for images that fill needs in our curated galleries. Our aim is to offer a comprehensive set of photos for each species that features all the varied plumages and subspecies for that particular bird. If you happen to add a photo to our community gallery that shows a plumage or subspecies that we don't have, we will ask your permission to add it to our curated gallery. Just this morning, I was reviewing our Community Photos for White-crowned Sparrow and found four images that I added to our Identification Photos gallery for that species. 

I found this wonderful photo in our Community Photos gallery. This "Nuttall's" White-crowned Sparrow (Z. l. nuttalli), photographed at San Francisco, California 2 May 2011, is going through its first prealternate molt and transitioning from an immature plumage its first adult-like alternate plumage. Interestingly, by this date most first spring White-crowned Sparrows have completed their prealternate molt and are showing definitive black and white crown stripes. (Photo by Rick Leinen) 

This screen grab shows an example of a helpful Field Note posted directly to the Red-throated Loon page. 

Finally, you can add  a "Field Note" to any species page (see example above). If you think that you've learned or discovered a behavioral or plumage clue that might help others more easily identify a particular species, we invite you to share it with the community. Printed field guides are great, but they are no match for the knowledge acquired through our collective birding experiences. If enough folks think that your Field Note is helpful and useful, we will incorporate it into our species account. 

We invite you to create an account and start contributing to the BirdFellow Social Field Guide today.