Friday, March 18, 2016

eBird checklists and miles traveled

One of the tasks that eBird reviewers find difficult is dealing with checklists that involve long, traveling counts.  Such checklists often stand out because they tend to rack up relatively large numbers of individual species, thus tickling the relevant filter and getting particular species entries flagged.  However, a large percentage of such checklists have no flags, thus do not see review until and unless a reviewer goes searching for anomalous eBird locations of habitat-restricted species, such as, say, White-tailed Ptarmigan.  In fact, these habitat- and range-restricted species are the primary argument for having checklists with as precise a location as possible, else the resultant eBird maps show occurrence in areas or habitats in which the species does not occur.

Unfortunately, the most comprehensive treatment of the subject is not that comprehensive and does not provide any hard-and-fast ground rules.  Granted, hard-and-fast rules when dealing with biology are nearly impossible, but eBird does care, and care strongly, about checklist locations.  In fact, I'm sure that if it were possible, eBird would prefer a checklist and associated precise location for every individual bird.  Of course, that is not going to happen, at least, not anytime soon.  However impossible the every-bird-is-its-own-checklist pipe dream might be, there are definite and very strong advantages to eBird of having checklists cover as little distance as we can get from eBirders.

The best guidance that I have found in the eBird 'Help' tab is the "Traveling Counts" section of a general-purpose essay on making checklists more useful:


Traveling counts have proven to be the most effective type of observation for modeling bird populations at large scales.  By doing these counts, birders often detect a good proportion of the birds in a given habitat.  It is critical, however, that your traveling counts not be too long.  Our analysts are able to effectively use traveling counts that are ≤5 miles [emphasis added].  Most birding that is conducted on foot easily falls within this window, but traveling counts by car can often be longer.  Please consider breaking up your long traveling counts into shorter-distance ones. It's best if these shorter counts are in a relatively consistent habitat, or do not pass through habitats that are too different. For example, a logical point to break a longer route into segments would be a transition between forest and farmland, as the birds found in these two habitat types are vastly different. Doing so would make information associated with each location — such as vegetation information from satellite images — more informative.  Plot your location at the center of the area traveled, not at the start point or end point.  It's okay to stop and spend time searching flocks of birds more thoroughly on traveling counts, as we are not assuming that you are traveling at a constant speed.  You're birding after all!
I here note that eBird Central has repeatedly stressed that this "five-mile limit" should NOT be considered cause, in and of itself, for checklist invalidation, that the limit is simply one that is very useful in particular types of analyses, such as the STEM maps of migration of individual species.  Checklists covering trips of a reasonable longer distance are certainly permitted in eBird and most such provide perfectly valid and useful data.  The problem that eBird reviewers face is where to draw the line on "reasonable."

Certainly, any eBirder should recognize that a checklist covering 650 miles on I-80 and crossing a state boundary (possibly, multiple state boundaries) and who knows now many dozens of county boundaries, does not provide data useful to anyone other than the observer.  In fact, such would provide misleading information, as almost no matter where such a checklist were plotted, the list of birds could well include species not regularly found at or near the plotted location.  But where lies the "reasonable" cutoff between 650 miles and five miles?  Unfortunately, this illusory line is dependent upon where you are and what sort of areas are covered by the checklist.

In much of the flatlands of Wyoming and Colorado, a checklist covering 15 miles, even 20 miles, might include just one or two habitats (e. g., native grassland and winter-wheat fields) that share a large proportion of bird species present in the area, and thus provide reasonable eBird data.  However, in places like southwestern Huerfano County, Colorado, traveling on the road from Highway 12 toward Trinchera Peak -- the straight-line distance of which is just over 4 miles (though the road distance is a fair bit longer) -- one's elevation changes from roughly 9250 feet to over 12,100 feet.  This road takes one from about the upper limit of elevational range of species like Pygmy Nuthatch and Black-headed Grosbeak and the lower elevational limit of Gray Jay and Pine Grosbeak to the above-timberline habitat of White-tailed Ptarmigan and American Pipit.  Thus, any checklist covering the whole road will, perforce, require plotting some of the birds encountered in habitat different from that in which they typically occur.

The above brings us back to the aforementioned eBird guideline about traveling distance and its emphasis on habitat.  Though not stated precisely in the guideline, eBird is very much interested in checklist locations being fairly specific to the habitats of the species included on the checklist.  Thus, in areas of the two-state region in which many habitats meet and mingle -- particularly obviously differing habitats, such as grassland and woodland or conifer forest and alpine tundra, the more precisely that locations are plotted and the shorter distances that are covered by individual checklists the better.  With the eBird application (app) for smart phones (about which, please read the best-practices essay), this becomes quite easy to manage.  Granted, cell coverage in much of the two states leaves much to be desired, but there is a simple work-around when planning a trip to an area of poor cell coverage.  One can modify this technique when already out and unexpectedly (or otherwise) run into poor cell reception, by using an existing checklist in the app on which to base the new one.  It is important to remember in such cases that county boundaries are often filter-region boundaries and species that are expected in some counties (thus, not flagged by occurrence, alone) may be unusual in a neighboring county, which may cause some slight disconnects between what species one sees and the "allowable" list of species on the current active checklist on the app.

Most eBirders understand the need to separate sightings in one county from those in another into different checklists.  While this is less of a problem in Wyoming than it is in Colorado (mostly due to the many fewer counties in Wyoming), both states host birding locations that cross county borders, with Yellowstone N. P. being the mother of all examples in the two-state region (heck, the Park even straddles multiple state borders!).  In Colorado, particular problem children birding sites include Chatfield S. P., Jumbo Reservoir, and Comanche N. G.  However, the single most-recalcitrant problem child is the area around Denver International Airport (DIA).

The DIA problem was created when the airport was first proposed, because Denver County was allowed to annex a sizable chunk of what was then Adams County in order to build the airport and the access road (Peña Boulevard). This action created a long, snaking corridor of Denver cutting through Adams.  Were it not for Denver County's small size and its near-complete lack of native habitat, the DIA problem would not be a problem.  However, with birders' interest in county listing, this long snake of a Denver extension travels through some excellent habitat otherwise lacking in the county and providing access to species that have been extirpated from the original county boundary... such as Burrowing Owl.  The whole eBird-review problem here is based on the fact that this corridor of Denver is so narrow, just 1.3 miles wide at its narrowest, thus it is nearly impossible on a birding jaunt of the area to not cross into and out of Adams County, sometimes multiple times.  This all means that most (if not nearly all) eBird checklists submitted from the DIA environs cover an area claimed by multiple counties, something that is not "permissible" in eBird.

In summary, I provide what I think are some reasonable guidelines on when to end the current eBird checklist and start a new one.
  • When a state boundary is crossed
  • When a county boundary is crossed
  • When crossing an obvious boundary between open habitat and wooded or forested habitat
  • When arriving at a birding location (particularly one that is an eBird hotspot) that has well defined borders and that is managed by a particular government agency or non-governmental organization (e. g., a state park, a national wildlife refuge, a private preserve)
  • When leaving a birding location (particularly one that is an eBird hotspot) that has well defined borders and that is managed by a particular government agency or non-governmental organization (e. g., a state park, a national wildlife refuge, a private preserve)
  • When leaving the "understood" area of an eBird hotspot, even if that hotspot lacks well defined borders (e. g., "Yellowstone NP--Midway Geyser Basin" or "Rocky Mountain NP--Endovalley")
  • When accruing 15 miles of distance in relatively homogeneous habitat in open country (such as in sage shrubsteppe, grassland, agriculture)
  • When accruing 5 miles of distance in relatively homogeneous forested habitat without significant (750 feet) elevational change
  • When accruing 2 miles of distance when encountering relatively significant elevational change (>750 feet, 1500 feet)
  • When accruing 1 mile of distance when encountering significant elevational change (>1500 feet)
  • When accruing two hours of observation (one hour would be even better)

Sunday, February 21, 2016

Update on Colorado and Wyoming filters

It has been more than long enough for another post on this venue, and I apologize for that for myself and the rest of the two states' eBird reviewers.  Personally, long work days and many other writing commitments can be blamed.  Of course, if I didn't go birding, I'd have more time to write about birding.

As I alluded in a previous post, eBird is interested in pursuing more and better habitat-based filter regions, rather than the current system of using geopolitical boundaries to define them.  As part and parcel of that interest, Don Jones (a member of the Wyoming review team) will be putting together a proposal for such for Wyoming as part of his undergraduate work (as the Brits would say) at university.  I have spent some time in designing such a system for Colorado, and have nearly completed a first-draft version for eastern Colorado.  Though Colorado's plains may seem to be easier to deal with in this regard than is the rest of the state, the reverse is actually true.  The extreme topography gradients in western Colorado actually preclude making small, tight filter regions (one would need 100s of the things!), so fairly large filter regions will still be the easiest way to treat that part of the state.  In eastern Colorado, however, there are numerous large reservoirs that attract a very different avifauna compared to most of the rest of the area.  In addition, the large urban area with their de rigeur tree canopy also make for very different bird habitat than found on the rest of the plains.  My current map has 26 regions defined from east of the Front Range-Wet Mountains-Sangre de Cristos Mountains line, where there are currently 20 regions, eight of which extend well up into the mountains.  eBird is not yet ready to greatly expand the number of "arbitrary polygons" used as filter-region boundaries, but when they are ready, Colorado and Wyoming will be ready, too.

Since February 2015, I have split Cheyenne and Kiowa counties out of the former Southeast Region into their own regions, bringing us to 39 current Colorado eBird filter regions, and with the Southeast Region no longer named such, as the remaining multi-county region is now titled Bent and Prowers.  I had plans to split those last two counties, but have decided to spend the necessary time on designing arbitrary polygons, instead, which will (hopefully soon) negate any effort to make individual filters specific to Bent and Prowers counties.

Finally, I continue to fine tune existing filters, which may cause some to many data that may have resided comfortably in eBird for years to suddenly get flagged.  Please do not be alarmed when you receive a request from one of us regarding a sighting from last year or from five years ago.  This is a normal process, one that is greatly aided by the great increase in amount of eBird data available to analyze how filters might be made more precise.  That is, thanks to you, eBird becomes stronger and stronger in its ability to define geographic and temporal bird occurrence in Colorado and Wyoming and the rest of the world.

Thursday, April 16, 2015

Colorado filter news

While this post will have little or no bearing on Wyoming birders, I write to inform the Colorado birding community that oversight of Kiowa County eBird entries is now managed by a county-specific filter rather than the broad (but getting less broad by the month) southeast Colorado filter.  This means that various species that are of regular occurrence in general in the southeast, but rare in Kiowa County will have more-meaningful filter limits.

Kiowa County eBird data include reports of 288 species, but many birders might be surprised by the number and variety of species for which there are no acceptable eBird reports from the county.  This list includes:







and


Other species are so rare in the Kiowa eBird data set as to make for the seemingly preposterous phenomenon that there are more records for Reddish Egret than (among many others) such species as Red-breasted Merganser, Northern Bobwhite, Virginia Rail, Wilson's Snipe, White-winged Dove, Yellow-billed Cuckoo, Black-capped Chickadee, White-breasted Nuthatch, Brown Creeper, Eastern Bluebird, Sage Thrasher, Indigo Bunting, and Baltimore Oriole.

The next items on my to-do list are filters for Cheyenne (it is not particularly similar to anything else in the former southeast filter -- Baca, Bent, Crowley, Kiowa, Otero, and Prowers; note the water aspect of those counties), Archuleta and La Plata, and Lake.


Friday, April 10, 2015

Cornell Laboratory of Ornithology World Big Day!

The Cornell Laboratory of Ornithology has announced a worldwide Big Day to be conducted on 9 May 2015, with the goal of getting as many as possible of the world's bird species recorded in eBird. Our two-state region can offer a couple of species unavailable almost anywhere else, Gunnison Sage-Grouse and Brown-capped Rosy-Finch. It also provides access to a number of bird species that can be difficult to find on demand, but which can be difficult elsewhere, including Trumpeter Swan, Harlequin Duck, Barrow's Goldeneye, White-tailed Ptarmigan, Dusky Grouse, Lesser Prairie-Chicken, Black Rail, Mountain Plover, Flammulated Owl, Northern Pygmy-Owl, Boreal Owl, Broad-tailed Hummingbird, Williamson's Sapsucker, Sage Thrasher, and Green-tailed Towhee. Alas, Black Swifts will not be in by then.

Brown-capped Rosy-Finch - Snowy Range, Albany Co., WY © Shawn Billerman
White-tailed Ptarmigan - Rocky Mountain National Park, Larimer Co., CO © Shawn Billerman

I encourage the region's birders to assist the Lab in this endeavor by getting out and birding on 9 May and entering the resultant data into eBird. However, I have a couple of cautions for those doing so. Entering data at a local level, such as at an individual park (though not one the size of Yellowstone N. P.!) is much more useful than is a checklist covering the birding of half a day at a large number of locations. County-level lists are particularly inappropriate, especially in counties with large elevational ranges, which often result in high-elevation species being mapped at low-elevation sites and vice-versa. I particularly encourage those with the interest and/or easy access to any of the above-listed species to make an effort to find these species as, who knows, your detection might well be the only one in the world that day! Other owl species are also of particular interest, particularly the more-difficult species: Long-eared, Short-eared, and Northern Saw-whet Owls. (A caution about heard-only Boreal Owls -- winnowing Wilson's Snipe are often mistaken for Boreal Owl.)

Other states are taking part in this endeavor, with some considering informal competitions between/among counties. Perhaps the host of Boulder County birders could challenge the Larimer County birders or Wyoming birders in/near Natrona County could challenge those in/near Fremont County. Another type of challenge might be to bird some poorly-known county or portion of a county, as data from such areas is even more valuable due to the relative paucity of existing data from them. As a Colorado example, there are very few data in eBird from Hinsdale, Mineral, or Pitkin counties from the second week of May, while there are NO data in that week from either Lake or San Juan counties! (As something of an aside, check out how many weeks have NO data in eBird from these counties: Costilla, Dolores, Hinsdale, Mineral, Rio Blanco, and San Miguel counties.)

Challenge or no, I encourage all of the region's birders to get out on 9 May and enter the resultant data into eBird!

Saturday, March 14, 2015

The arrival of Swainson's Hawks

As the time approaches in which the first Swainson's Hawk of spring is eagerly anticipated, I feel that a caution is warranted.  While the identification of Swainson's Hawk is generally considered to be fairly straightforward, there are a few situations in which identifying a bird as a Swainson's Hawk is less than straightforward.  In all of these situations, the difficulty lies in not understanding the whole range of plumage possibilities in other species.  I have treated one of these:  light juvenile Swainson's Hawk vs. light adult male Rough-legged Hawk.  Another is the Bald Eagle plumage termed "White Belly I" by Clark and Wheeler, in which individuals have white wing linings and belly contrasting with dark flight feathers.  The third situation, and the impetus for this short essay, involves certain adult Red-tailed Hawks.

Steve Mlodinow sent me a photograph this morning (Fig. 1) that seems to show a buteo with a reddish bib, nearly unmarked underparts, and very little in the way of white markings on the scapulars.  Looking at the picture, I can certainly see how someone could go astray in the ID process!

Figure 1. Adult Red-tailed Hawk, Union Reservoir, Weld Co., CO, 9 March 2015. Photo by Steven G. Mlodinow.

However, with a bit closer scrutiny, we can see that it is just the sides of the breast that are reddish; the center is white.  Many adult Eastern (subspecies borealis) Red-tailed Hawks, at least those breeding at the latitude of Colorado (very few at the latitude of Michigan; pers. obs.), have little in the way of a belly band, thus enhancing the similarity with Swainson's Hawk.