Ask Maine Audubon: Where are the baby ducks this summer?
Monitoring bird populations can be difficult, especially on a small scale. It can be very difficult to answer a single question about a noticeable decline in birds, but often times we know, depending on the season or more important factors at play, why birds may or may not be detected. My last column, answering “where are the birds?” is a great example of how each year, at the end of summer, we know birds all over the state are seen less frequently, and for good reason. However, another round of inquiries this summer puzzled me a little: where are the baby ducks?
Mallards, especially those on the southern Maine coast and urbanized areas, will begin their first nesting cycle in early April, and we usually see the first fluffy yellow chicks in mid-May. Things looked normal this spring from my limited observations, and it was especially in the second half of summer that I started to learn about the lack of baby ducks, such as from David and Janice who live on the Spurwink River and report seeing them every year – until now. Looking at data from Cornell’s eBird, an online database for people to submit bird sightings, the frequency of mallards this year is comparable to the past five years, so statewide, there was no obvious decline.
This winter we will be able to browse through the breeding records that are submitted to the Maine Bird Atlas, a Maine Department of Inland Fisheries and Wildlife project to document the breeding and wintering distribution of Maine birds, and possibly some of the fluctuations. annuals. But for now, maybe I had better be honest and say, “I don’t know! When asked what happened to these ducklings later.
I did some research on mallard nesting to see if there were any obvious factors that could have been at play this year. An easy speculation to make is a connection with the drought conditions we experienced this summer. The phrase “happy as a duck in the water” is fairly accurate, with studies showing that mallards have more nesting attempts in the wettest years, and that in eastern North America there are a positive correlation between annual recruitment – how many new individuals are added to the population – and levels of precipitation in late winter and spring. In May, about 40% of Maine was rated “unusually dry” by the US Drought Monitor, which fell to 70% “moderate drought” at the end of June. These dry conditions may have been a factor.
Predation also comes to mind as a reason we wouldn’t see many babies. From snapping turtles and herons, to many mammals like foxes and raccoons, there are many predators that will prey on a mallard’s nest or newly hatched young. Maybe the last few years (everyone remembers all those acorns and the “squirrel-magedon” of 2018?) Have allowed the number of predators to increase. In my review of the literature, I found a fascinating study from California that showed a positive correlation between the abundance of small rodents and the nesting success of mallards. Apparently, when voles are abundant, some of the top predators of mallard nests will focus on rodents instead.
So I don’t have a clear answer yet. Keep submitting your observations to eBird and the Maine Bird Atlas and with more data we can hopefully learn more about the changes with our bird populations. In the meantime, this has been a fun question to ponder.
EVEN DOMESTIC CATS DO HARM
I had the pleasure of appearing on Maine Public’s Maine Calling show earlier this month to talk about birds and conservation. Naturally, the unnatural topic of cats has been brought up, as they are the number one human-made cause of bird mortality, representing a conservative estimate of over 2.4 billion bird deaths per year in the United States. like to do here – that the problem is only with feral cats. Although they are the worst for wildlife, they are only part of the problem.
The famous report (at least in conservation circles) by Scott Loss, Tom Will and Peter Marra (“The Impact of Free-Range Domestic Cats on United States Wildlife”, published in Nature Communications in 2013) which quantified the human activities that directly lead to bird mortality, estimated that property cats, allowed to be free-roaming, accounted for 684 million bird deaths each year.
Yes, it’s not as bad as the other 1.6 billion feral cat deaths (and remember, cats are a non-native species brought to this continent by humans), but that number still dominates. other anthropogenic causes. Construction impacts (birds colliding with glass) are $ 599 million, just below the contribution from possessed cats. Automobiles represent about 200 million, power lines 5 million and wind turbines 573,000.
Hope this clears up all the misconceptions. Any outdoor cat will follow their instincts to kill birds and other wildlife. Since we brought them to the mainland, we should have some responsibility towards the animals that were here first. It is also better for the health of our pets. Keep your cats indoors or watch their time outdoors. They will live long and happy, safe from rodenticides or predators, like my two cats, Ruth Bader Kittensburg and Sonia Kittehmayor.
Got a nature question for Doug? Email your questions to [email protected] and visit maineaudubon.org to learn more about bird walks, community science projects, and other wildlife and habitat programs.
Hunting: Numerous game populations in solid form as the seasons approach