Changes in eBird frequency since 2016

 

The eBird bar charts give us "frequency: the percentage of checklists reporting that species within a specified date range" - so it gives you an idea of how likely are you to encounter that species during that time frame in appropriate habitat.

These data don't really tell us about the actual abundance of the species - the size of their populations (because of the variety of counting methods and observer effort used to get these eBird data, and other things) ... but ... intuitively, if there are changes in frequency for really common birds - that must say something.

So, I have compared a species' frequency from December 2021 to the frequency from 2016 - in a very imprecise way that would not stand up to statistical analysis.  I have summed the year's frequency for 2016 and for 2021 and compared them by subtracting the 2016 number from the 2021 number.  Here are the results for the top and bottom 30 species - the 30 species that show the greatest increase or decrease in frequency since 2016.

 eBird Regional District of East Kootenay Frequency Difference

Showing 60 of the greatest frequency differences between the sum of eBird frequency for 2016 compared to the sum of eBird frequency for 2021 for 60 species in the Regional District of East Kootenay

English Name		BC_Game		Abundance		Diff_2021
American Crow				vc		3.912559532
Common Raven		g		vc		3.267595681
Canada Goose		g		vc		2.520634189
Northern Flicker				vc		2.459357979
Bald Eagle				c		2.431250047
Mallard		g		vc		2.289990853
Red-breasted Nuthatch				vc		2.125886915
Dark-eyed Junco				vc		1.596265554
American Robin				vc		1.506643623
Rock Pigeon		g		vc		1.454782405
Blue Jay				sc		1.313311740
Eurasian Collared-Dove		g		sc		1.255200966
Black-billed Magpie				c		1.118253242
Bufflehead		g		c		1.115452534
American Wigeon		g		c		1.098214353
American Coot		g		c		1.089445026
Turkey Vulture				sc		0.987196201
Pine Siskin				vc		0.920770842
European Starling				vc		0.916598597
Townsend's Solitaire				c		0.910150795
Red-tailed Hawk				c		0.876833943
Ring-necked Duck		g		c		0.863093321
Trumpeter Swan				sr		0.862401577
Tree Swallow				vc		0.835159263
Osprey				c		0.786232455
Green-winged Teal		g		c		0.763347806
Vesper Sparrow				c		0.760730881
Western Bluebird				c		0.744897794
Eastern Kingbird				c		0.731731785
Killdeer				c		0.730740303
English Name		BC_Game		Abundance		Diff_2021
Ruffed Grouse		g		c		-0.068174952
Barrow's Goldeneye				sc		-0.074931879
Calliope Hummingbird				sc		-0.088113133
White-crowned Sparrow				sc		-0.088878485
Black-headed Grosbeak				sr		-0.098174169
Brown-headed Cowbird				c		-0.098403200
Common Grackle				sc		-0.100154859
Northern Shrike				sc		-0.116332190
Black Tern				unc		-0.122280235
White-throated Sparrow				sr		-0.140874202
Northern Waterthrush				c		-0.155879991
MacGillivray's Warbler				c		-0.172119636
House Finch				vc		-0.181452069
Clark's Nutcracker				vc		-0.199776593
Warbling Vireo				c		-0.228123752
Great Blue Heron				sc		-0.229904927
Townsend's Warbler				c		-0.245286146
Hairy Woodpecker				vc		-0.249200275
Song Sparrow				vc		-0.265412316
American Dipper				c		-0.286035808
Vaux's Swift				c		-0.316657000
Rufous Hummingbird				c		-0.454750968
Bohemian Waxwing				c		-0.540717624
Common Redpoll				c		-0.571101261
Pine Grosbeak				c		-0.779422544
Black-capped Chickadee				vc		-0.803501285
Evening Grosbeak				c		-0.962873544
White-breasted Nuthatch				sc		-1.054325951
Downy Woodpecker				vc		-1.114156219
Steller's Jay				c		-1.154665009

 

So, now you are more likely to see American Crow, Common Raven, Canada Goose, Northern Flicker, and Bald Eagle, etc. when you go out birding; and less likely to see Steller's Jay, Downy Woodpecker, White-breasted Nuthatch, Evening Grosbeak, Black-capped Chickadee, etc. than you would have five years ago.

I think decreases in the very common (vc) species indicates there are some population problems with them: they used to be commonly seen but are seen less often now, probably because there are fewer of them around, not because of some change in their behaviour or birders' behaviour.  And fewer of them around either because their populations are smaller or because there is less habitat available for them.

This is troublesome to think about for Downy Woodpecker and Black-capped Chickadee, especially.  Why?  They are easily identifyable and still fairly common but why would they be reported less unless there are just fewer of them to report?  And Hairy Woodpecker and Song Sparrow?  What's up with them?  And Rufous Hummingbird - hmm.

Clark's Nutcrackers and Great Blue Heron we know are having trouble. Nutcrackers with food supply in higher elevations: less productive limber pine seed crop, limber seeds having higher energy rewards than lodgepole pine.  And Herons having trouble with finding suitable nesting sites - and maybe more predation from a higher Bald Eagle population?

It's good to see Northern Flicker increase in frequency - they carve out lots of cavities for other birds to use as nests and help recycle dead trees.  Eurasian Collared-Dove we know has just "recently" arrived in the area and their population is currently growing rapidly.  They used to be rare but it didn't take long for them to become quite noticeable in human-settled areas.

The increasing frequency of seeing Bald Eagles:  if their numbers are indeed growing, that is fine - we need "top of the food chain" species as part of the overall balance.  Why would they be increasing?  Maybe warmer springs lets them get going earlier laying eggs and that translates to better survival of young?  Maybe they are taking advantage of having more Mallards around to eat?

So, yeah, the 2021 frequency data is cumulative and includes the same data as in the 2016 number.  Both frequency numbers contain all the data in eBird up until that point in time.  That adds some evening.  This is not comparing 2016 and earlier to the time frame of 2017 - 2021.

You can see the eBird bar chart here: https://ebird.org/barchart?byr=1900&eyr=2020&bmo=1&emo=12&r=CA-BC-EK

 And you can change the dates to see the differences for yourself, and you can download the numbers - scroll to bottom, "Download Histogram Data".

Yes, there are more eBirders now, but this is frequency data - so that is factored in.  What is not factored in is skill of the eBirder at detection and many other things - that's why this discussion is not very rigorous scientifically but it does give one something to think about.

 

 

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.

Disclaimers

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.



:-P