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Snowy Owl sightings and statistics

Snowy Owls have exploded across the eastern half of the United States since I blogged about the possible invasion coming this season. There has been an unbelievable push of birds heading to the south and concentrated in the Great Lakes to Northeast and the Atlantic Coast and continuing south by the day. Two years ago we had a similar burst of Snowy Owls pour down into the U.S. but it was more uniformly spread across the upper half of the country. Many Central and Northwest areas had sizable numbers of birds while the Northeast and Atlantic Coast had fewer. Why is there such a difference in geography? We don’t know, at least not yet, and all of this is a good reason for you to be a citizen scientist and report your Snowy Owl sightings to eBird. If you are concerned about their location being broadcast to a very small minority of overzealous birders or photographers then you can certainly wait a month or two before you enter the sighting and you do not have to be extremely precise with the location.

Let’s take a look at some eBird maps! First, this is the map I posted on November 23.

Snowy Owl eBird map Nov 2013

That looks a lot different than the much busier one I posted to our Facebook page on November 30.

SNOW 11-30

And this map from the afternoon of December 3 is, in a word, insane!

SNOW 12-03

There have already been Snowy Owls all the way down to areas south of St. Louis, in North Carolina, and even Bermuda!  That is absolutely incredible, and even this stunning image does not do the invasion justice as it represents individual sightings and not the total numbers of birds present. Some spots have had two, three, several or even more birds occurring simultaneously. At other locations dedicated observers have been able to differentiate between individual birds depending on how much barring they have on their feathers along with other identifiable features (like a deformed eye in one case) and count the growing cumulative total that have passed through the location thus far this season. Generally one can identify females vs. males by how dark the birds are with females featuring more barring, especially on the tail, neck, and bib, and the males with lighter bars and whiter overall. A similar system follows for aging as immature males will have some barring scattered over their body that they will lose over time and immature females will be extremely dark overall with thick, bold barring. Of course this makes for an overlap and it takes some time and studying to be certain for some individuals, and we cannot always be certain for all of them.

Let’s talk numbers once again thanks to eBird with data as of the afternoon of December 3. Here’s the Snowy Owl frequency graph for November and December 2013 with frequency defined as the percentage of all eBird checklists within the period reporting the species.

SNOW eBird frequency 12-03-13
As you can see this is a steady climb each week to the current one since the invasion begin with about 3.6% of all checklists from December 1 to December 3 having at least one Snowy Owl on them. Here’s the average count, the number of Snowy Owls seen on average when the species is recorded.

SNOW eBird average count 12-03-13

Once again the peak is the current week, December 1 to December 3, with nearly 1.5 birds per sighting. This somewhat goes along with anecdotal reports that more and more seem to be featuring multiple birds at given sites. Here is the high count graph which means just that – the highest count of the species entered into eBird for each week.

SNOW eBird high count 12-03-13

This peak is at 9 (!) birds in the week of November 22. Even the 6 from the week before and 5 so far this week are very high. I have seen many Snowy Owls, but I do not think I have ever seen multiple birds at one place. I cannot even imagine what 9 would look like. There have been other reports of several birds together on the Atlantic Coast in the last couple of weeks but this unfathomable report from the far reaches of Newfoundland of 138 Snowy Owls (1-3-8!!!) sets the bar way beyond anything we could find on American shores. I have no idea how many they regularly see or what their records are but I am going to guess that sort of day is uncommon to say the least. Finally, here’s the total count eBird graph for the sum of all Snowy Owls seen each week.

SNOW eBird total count 12-03-13

During the first week of the irruption starting on November 8 there were 9 birds entered into eBird. The following week, November 15, this shot up to 51. November 22 skyrocketed to 940, and so far this week there have been 457. Bear in mind that these totals are of course not reflecting many Snowy Owls that have yet to be entered and in some cases there are many that will never be entered because not everyone uses eBird. On the other hand there are many Snowy Owls being double counted as birders flock to a given location to view and then enter the same bird or birds. This data does tell us some stories, and by the time spring rolls around and more birds are discovered, recorded and entered heading south and then back to the north we will have a broader and clearer picture of what is going on. For now what we know is this seems to be a massive movement with an intriguing geographic concentration. Where will they spend the winter? Will they be found even further south or in any numbers to the west? Is this the result of a population boom or a prey bust? Let’s keep tracking this and see what we can figure out in the next several months. We will have more data, information, photos and hopefully videos of these magnificent birds to share with you soon.

 

Scott Kruitbosch
Conservation & Outreach Coordinator