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Blog Birding #145

Juvenile and immature are terms that are often used interchangeably among birders, but Dave Irons at Birdfellow explains just what is the different between these all-too-similar and occasionally overlapping definitions:

If you see a hatch-year thrush, warbler, or sparrow in July and then see that same bird in September, its appearance will have changed dramatically. Think of what an American Robin, Yellow-rumped Warbler or Dark-eyed Junco looks like when it is still being fed by an adult. By the first of October, you won’t be seeing spots on the breast of the robin and the uniform streaking that marked the underparts of the warbler and  the junco in July will be long gone.

Greg Miller has been spending a lot of time trying mixing and matching eBird data in interesting ways and thinking about how to get the most use out of it:

Look at #1.  The number shown is 375.  But if you remember when we were downloading this information it only had 342 species, right?  Where did the extra species come from?  Ah, I am glad you asked.  Look at #2.  See the “(Domestic type)”?  Yeah.  That counts as “taxa”, but not as a species.  First on our list will be cleaning up our spreadsheet and filtering out the non species.

Gulls can be difficult enough without considering the myriad ways lighting can affect our interpretation of their plumage. Amar Ayyash at Anything Larus goes there, though:

The Bonaparte’s on the far left looks paler than the other five. Does it suffer from a pigmentation condition that’s yet to be explained by ornithologists? Of course not. It happens to be the only individual (along with the Little) that is almost exactly parallel with the camera lens (i.e., the observer). The other five Bonaparte’s are all facing towards the observer’s ten-o’clock. A slight change in this so-called angle-to-observer can dramatically change our perception of the grays we’re seeing. The effect is multiplied on sunny days.

Geolocaters have been the seemingly magical tools behind so many of the most fascinating bird study results of late, but they can shine light on local birds too. Take a look at the research being done on Gray Catbirds at the Rouge River Bird Observatory at Net Results:

In fall 2012, we put 2 more geolocators on birds, but did not see any birds with geolocators in spring 2013, despite a lot of patient observation of the catbirds on site. Earlier this year, Dr. Bowlin received a grant to purchase 26 new geolocators with longer light-collecting stems better suited for catbird study. You can see the older device below in the top picture, and a newer one with the longer “stem” in the bottom photo. They both weigh the same, 1 gram including the harness.

I love reading about Big Days, particularly when those reports come with a lot of photos. Dan Arndt of Birds Calgary shares one such Alberta Big Day:

Quite a bit of planning went into our attempt, with many hours collecting data from eBird and the Albertabird Yahoo Group, and using Google Maps to plan our route to maximize the time we’d have outside of the vehicle to find our target birds at each stop. Our original plan was to start at Cold Lake before dawn, listening for as many warbler and vireo species as we could identify by ear, head to a few other ponds and lakes near Cold Lake, then begin driving down the east edge of the province, stopping briefly at a few spots along the way to pick up other targets that are only found in the boreal and parkland biomes, before hitting up Dinosaur Provincial Park for the badlands and prairie specialists there.


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Nate Swick

Nate Swick

Editor, Social Media Manager at American Birding Association
Nate Swick is the editor of the American Birding Association Blog, social media manager for the ABA, and the host of the American Birding Podcast. He lives in Greensboro, North Carolina, with his wife, Danielle, and two young children. He is the author of Birding for the Curious and The ABA Field Guide to Birds of the Carolinas.
Nate Swick

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  • Mary

    An exceptionally informative collection this time, especially the one about imm/juv. My NBS (non-birding spouse) has been pressing me to answer this question for a while.

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