02 May 2015

eBird Data - Five Year Comparison

What is eBird

eBird is a free online bird distribution database where anyone can submit bird sightings.  In return, contributors get a digital version of their sightings, accessible from any internet capable device, which can be summarized in various ways and downloaded. They also get their checklists organized by geo-political area, the ability to compare their birding activities to others (Top 100), exchange checklists with other users, and much more.

From this world-wide collective effort, the general public can access various data summaries and visualizations - for free! Researchers can pay to receive specific data sets including effort data used to calculate frequencies and bird population estimates.  As eBird contributions grow, our collective documentation of bird distribution throughout the year and in different areas is getting filled in.

What is this post about

While doing some computer file maintenance, I ran across screen captures I took 5 years ago of the eBird bar charts for my area and thought it would be interesting to compare them to the present.  My main purpose for this post is to show how terrific it is to have more eBirders and more checklists coming in. They do actually show something.

Keep in mind that the bar charts are frequency histograms representing the frequency a species was recorded on complete checklists each week.  As such, they don't tell you the population size just how likely you were to see / record that species (in suitable habitat and all that stuff).  But, if there are more birds around, ie. a larger population, you are more likely to record them, it seems to me.

Differences in the 5-year spread of bar charts may be a result of changes in bird populations or they may simply be from there being a greater numbers of birders and/or checklists submitted in the area.  I can't tell, and since I had to take statistics twice in university and all I remember are the words 'Anova' and 'Chi squared', I wouldn't trust any statistical analysis I could possibly conjure anyway, but I hope you also find them interesting.

They say over 40% of the bird species in Canada have declining populations (Birdlife Data Zone).  But on the other hand, there are more birders and more eBird data. More public data is good.  Things are changing in the natural world (which includes us).

The East Kootenay

To me, the East Kootenay (Regional District of East Kootenay / East Kootenay 'county' on eBird) is a prime place to study the impacts of climate change. It has a lot of mountains but it also has the East Kootenay Trench.  This valley was once mostly grassland and is undergoing some restoration. It is also feeling the effects of warmer temperatures and changing weather patterns.  A couple of mountain passes connect it to the prairies east of the Rockies - which birds can access and to the south are the lower elevations of Montana and Idaho.

Comparison details

Following are comparisons, about 5 years apart, of the bar charts of selected species occurring in my area. The top bar chart in each picture are from 2010 and the bottom from 2015.  Due to lack of foresight, the relative scales are not totally in proportion; ie. the months don't line up, but since these comparisons are mostly for curiosity's sake, I trust you forgive me.

2010 was the third year of the 5-year effort of the British Columbia Breeding Bird Atlas which ran from 2008 to 2012.  A dedicated handful of locals and dozens of others contributed eBird sightings as a result of the Atlas.


I present possible explanations for the differences as points of discussion - I have no scientific bases for these and most are drawn from my own simple experiences.  Suffice to say that ALL differences have been impacted by increased observer coverage: more people going more places and submitting more checklists to varying degrees.

Also, these views represent my own and are in no way reflective of the eBird institution nor Cornell.  You too can look at the data on the website and come up with all kinds of your own crazy ideas of what is happening with birds in the world.

Bird's range expansion

Some species have definitely expanded their range and time spent in the East Kootenay

Common Grackle year-round distribution East Kootenay BC; Jun 2010 (top), Apr 2015 (bottom)
The first eBird record of Common Grackle in the East Kootenay appears to be from the Crowsnest Pass in 1991. By 2006 it started showing up in Fernie during the breeding season and now there is a stable and growing breeding population there. It will likely spread southwest down the Elk River. It may be coming up from Montana as well.  In this case, the changes in the bar chart are likely from a combination of more checklists submitted and increased population.

Some Doves' year-round distribution East Kootenay BC; Jun 2010 (top), Apr 2015 (bottom)
Eurasian Collared-Doves were just a rumor in the area in 2010. Now they're well established in many places.

Some local population increase / range expansion

Blue Jay year-round distribution East Kootenay BC; Jun 2010 (top), Apr 2015 (bottom)
Blue Jays were first recorded in the early 1970s. (1976 on eBird). Since then, their population has slowly increased and their range spread. They are now a recognizable winter feeder bird in many towns. They mix it up pretty good with Stellar's Jays all year round.

Sandhill Crane year-round distribution East Kootenay BC; Jun 2010 (top), Apr 2015 (bottom)
Sandhill Crane were first recorded on eBird in 1995 near Bummer's Flats. Now they have been seen in breeding season from Wardner to Brisco.

Here's how southeastern BC cranes mix it up on the dance floor.

Peregrine Falcon year-round distribution East Kootenay BC; Jun 2010 (top), Apr 2015 (bottom)
Peregrine Falcon recovery may be extending to the East Kootenay.

Barred Owl year-round distribution East Kootenay BC; Jun 2010 (top), Apr 2015 (bottom)
Maybe some population increase for Barred Owl since there are more detections outside the Nocturnal Owl Survey season.

Definitely not sure what?

American Tree Sparrow year-round distribution East Kootenay BC; Jun 2010 (top), Apr 2015 (bottom)
A bunch of summer American Tree Sparrow records disappeared from the database, thank goodness, as did some other species.

Bonaparte's Gull year-round distribution East Kootenay BC; Jun 2010 (top), Apr 2015 (bottom)

Could be increased coverage, could be population increases / range fill-in for the Bonaparte's Gull.  I separate this one from the following which are likely mostly a result of better coverage because I can't think of a reason why more Bonies would be spotted throughout summer now compared to five years ago since they're not that difficult to detect or identify.

Increased coverage, observer skills, and / or foreign observers?

Northern Saw-whet Owl distribution East Kootenay BC; Jun 2010 (top), Apr 2015 (bottom)
More detections in late spring for Northern Saw-whet Owl in the area.

Great-horned Owl distribution East Kootenay BC; Jun 201 (top), Apr 2015 (bottom)
More people paying attention to Great-horned Owl throughout the year?

Northern Goshawk distribution East Kootenay BC; Jun 2010 (top), Apr 2015 (bottom)

Northern Goshawk were a local subject of study by the provincial government. Nice those records got in to eBird and the Breeding Bird Atlas.

Cooper's Hawk distribution East Kootenay BC; Jun 2010 (top), Apr 2015 (bottom)
Cooper's Hawk got a few more sightings reported over winter, maybe around feeders? and quite a few in mid-summer.  Maybe better survival in winter meant more young fledged?

Sharp-shinned Hawk distribution East Kootenay BC; Jun 2010 (top), Apr 2015 (bottom)
Sharp-shinned Hawk were definitely spotted more often all year round. Perhaps more people are better at distinguishing them from Cooper's, as well as more overall coverage and perhaps better winter survival rates?

Purple Finch distribution East Kootenay BC; Jun 2010 (top), Apr 2015 (bottom)
I think the increase of Purple Finch records is mostly a result of people from outside the area who know what they're looking for.

Pine Grosbeak distribution East Kootenay BC; Jun 2010 (top); Apr 2015 (bottom)
There have been more sightings of Pine Grosbeak reported over the summer in the last five years.  Perhaps more people are going to higher elevations in the summer.

House Wren distribution East Kootenay BC; Jun 2010 (top), Apr 2015 (bottom)
House Wren have been reported more consistently in recent years. I know I made an effort to report my local pair last year.

Virginia Rail distribution East Kootenay BC; Jun 2010 (top), Apr 2015 (bottom)

The change in the Virginia Rail bar chart is mostly a result of more reporting at Elizabeth Lake, Cranbrook BC.

MacGillivray's Warbler distribution East Kootenay BC; Jun 2010 (top), Apr 2015 (bottom)
More MacGillivray's Warbler seem to be around and even breeding. Could be we are just looking and listening more for them.

American Pipit distribution East Kootenay BC; Jun 2010 (top), Apr 2015 (bottom)
I think more people are tuned in to the American Pipit's faint call in the sunny wind, or perhaps there are more people going up higher in the summer.

Black-backed Woodpecker distribution East Kootenay BC; Jun 2010 (top), Apr 2015 (bottom)
After some big wildfires, adjacent to highways or biking trails, Black-backed Woodpecker got a lot easier to find so more people went looking for them more often, rather than having to go further up the back roads to some older burns.  Maybe there was actually an increase in their population as a result of more habitat.

Changes in Winter

American Goldfinch distribution East Kootenay BC; Jun 2010 (top), Apr 2015 (bottom)
I think more people have clued in to the fact that American Goldfinch are around in the winter and  look for them then. Or maybe with fewer Pine Siskin to compete with the last few winters, the Goldfinch can stick around and find some food in the winter.

Trumpeter Swan distribution East Kootenay BC; Jun 2010 (top), Apr 2015 (bottom)
There have been a marked increase of Trumpeter Swan records submitted from the upper Columbia part of the East Kootenay.  There are several new resident observers up there.

American Robin year-round distribution, East Kootenay BC; Jun 2010 (top), Apr 2015 (bottom)
Does this show that a few American Robin now hang around all winter? Or that more people are submitting winter records of a common / abundant species? Perhaps both.

Cedar Waxwing distribution East Kootenay BC; Jun 2010 (top), Apr 2015 (bottom)

Cedar Waxwing haven't changed much over the past five years except more people are picking them out of flocks in winter or having them come separately to feeders - just a few, mind you.

Pied-billed Grebe distribution East Kootenay BC; Jun 2010 (top), Apr 2015 (bottom)

The Pied-billed Grebe bar chart shows how deceptive making any inferences based on these charts can be.  There were only a handful of records of them in the winter since 2010 but from the bar chart, it looks like they are more consistently seen in the winter - not true.  So any or all of my comments above could be total bunk.

Seasonal distribution of two swallow species East Kootenay, BC; Jun 2010 (top), Apr 2015 (bottom)
Insectivorous bird species have declined 70% they say, yet the frequency of sighting them in the East Kootenay hasn't changed in the last five years.  I think more people are paying attention and looking for them, I know I am, and I have seen a definite decline in their numbers over the past 10 years.  The wires used to be lined with them, now they are not.

Actual statistical analysis from scientists is needed to make real sense of all this wonderful data.  First, the data has to be there.  Keep up the good work, eBirders.  Governments: keep your scientists on staff and hire back the ones you cut, idiots.


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