February is usually all about the ducks for my Ornithology class. However, this year we have come up short. No Common Goldeneyes, Lesser Scaup, Canvasbacks, Redheads, or Green-winged Teals. A handful of Common Mergansers, Northern Shovelers, and Northern Pintails. As always, still plenty of Mallards around! Overall, my impression is that duck numbers are really low this year. So, I decided to dig into eBird data to see if there was evidence of this beyond my own birding experience.
Focusing on the three Ohio counties that we bird, Montgomery, Greene, and Clark, I looked at the average number of ducks reported per checklist in January and February over the past five years. For all species that I examined, the number of ducks in 2020 was on the low end, and indeed, this year’s numbers were lower than any other for most species (the exception was that there were fewer Lesser Scaup reported in 2017). In the chart, I am showing the differences in average numbers for the diving ducks (genus Aythya), which are perhaps the most interesting. I’m also including Common Goldeneyes, because we typically see fairly large numbers of this species.
You can see that there are fewer numbers of all six species in 2020 compared to the 2016-2019 average. The biggest differences are seen in Canvasbacks and Redheads. For Canvasbacks, an average of about 0.5 ducks were reported per eBird checklist from 2016-2019 (about 1 duck for every 2 checklists), but in 2020, there were fewer than 0.1 ducks per checklists (1 duck for every 10 checklists). For the more abundant Redhead, an average of 4.3 ducks were reported per checklist from 2016 to 2019. However, in 2020, an average of only 0.7 individuals were reported. Thus, Redheads are typically six-times more abundant compared to this year! Even the lowest number of Redheads reported between 2016 and 2019, was four-times higher than in 2020! You can see this same pattern for all six species. So, I can conclude that yes, duck numbers are low this year, at least compared to the previous four years.
So, what is going on? Well, whereas changes in daylight (photoperiod) initiate migration for many of our migrant songbirds, ducks respond to local weather. They tend to move from northern areas when temperatures get cold and waters begin to freeze. As long as there are open bodies of water in the north, you can usually find ducks. This winter has been incredibly mild (I don’t think any of our larger bodies of water have frozen over), and my hypothesis (educated guess) is that many of our ducks could get away with migrating shorter distances. To test this hypothesis, I would need to compare numbers of ducks in more northern areas for the same time period and maybe see if those numbers are associated with average temperatures. Maybe another day! In the meantime, I guess I should feel lucky that this beautiful Redhead went the distance and ended up in one of my favorite waterfowl spots!
A question for you: do these data mesh with your own observations this winter? Let us know in the comments!
Old Reid Park, Clark Co., OH
4 March 2020