Monday, March 9, 2009

Northern flickers and European starlings

There have been three flickers in the yard everyday now for about a week or so, one female and two males. They seem to be fighting for her attention, and for the cold ants in our anthill . By Saturday morning it looked like one had the upper hand in the battle for her affection and the nest box (see the handsome gentleman above). The disconcerting, yet predictable part about flickers is there relationship with European starlings. Saturday morning also marked the first day of the year where I saw a European starling in my yard. This is not good, but I knew it would happen as soon as excavation started on the nest box.

Few are aware of the relationship between European starlings and flickers. A really unfortunate trend in the expansion of European starlings is the colonization and parasitism of flicker nesting cavities. Northern flickers are an incredibly vital component to forested ecosystems across the country. They are abundant primary excavators and so many species (secondary excavators) rely on them to hollow out nest sites in standing snags. The large cavities they create are used by other birds (including screech-owls, and American kestrels), and animals, after lfickers abandon them in the summer. Northern flickers are ground feeding woodpeckers that mainly eat ants. Because of their abundance, northern flickers can control populations of ants including wood-boring species.

As secondary excavators, European starlings, rerly on flickers to excavte a cavity and an entrance hole of roughly the same size as a northern flicker. The starlings let the flickers do the work of finding a suitable site, excavating a cavity and then the starlings move in to over take the flickers and seize the nesting cavity.

Northern flicker status: population declines
Recently there has been a lot of concern over status and population trends of northern flickers. Although they are still abundant, they have declined over the past 20 years. This decline is from a combination of factors, including habitat loss, nesting site loss, competition with European starlings, and even from lawn insecticides. These declines, coupled with the loss of habitat and ever-encroaching invasive species can have serious, deleterious effects on many bird species and other wildlife.

What you can do
Providing a nest box is a start, since snags are often removed, reducing the availability of nest sites for flickers and other cavity nesting species. But just providing a nesting place is not enough. It is a huge responsibility of nest box stewards to protect the nest box from invasion by European starlings.

If European starlings begin to use your nest box, do not just add more nest boxes to attract flickers - this will only get you more starlings. Do what you can to dissuade starlings from nesting, and this usually means lethal control, similar to squirrel management. However, begin first by plugging up any entrance holes where they may be nesting, remove their nesting material. Or remove their eggs.

Unlike woodpeckers, European starlings bring in nesting material to their cavities. This is likely an adaptation that most secondary cavity nesters employ. Since they do not excavate a clean, parasite-free area for their nestlings, they will line their nests with green, fragrant herbs as an insecticide.

Some think that northern flickers are adapting to European starlings nesting later, after European starlings have fledged. This is more than likely a nice little wish. With climate change and other factors, if nothing else, northern flicker (and other species) nesting dates might be getting earlier, rather than later. Nest timing is critical and centers on resource availability. If northern flickers are indeed nesting later, it is probably to their detriment.

European starlings in North America
European starlings have a very interesting and storied history in our country. The first two attempts to introduce the European starlings into North America failed; unfortunately the third attempt did not. There are now an estimated 200 million European starlings in North America, one-third of all the European starlings in the world. All the European starlings in North America descended from 100 that were released in New York’s Central Park by Eugene Schieffelin in 1890 (60 birds) and 1891 (40 birds).

Although many believe Schieffelin was trying to introduce every bird species mentioned in the works of Shakespeare to North America, there is little evidence to support this. It is more likely he was merely trying to control pests, and probably the same pests that he tried to get rid of when he introduced the house sparrow 30 years prior. Although the house sparrow, and European starling introductions were quite successful, fortunately his attempts to introduce bullfinches, chaffinches, nightingales, and skylarks were not. Busy guy.

Although ecologically devastating, biologically it is actually really interesting that European starlings survived and flourished, despite being descended from such a small source. Evidently, this genetic bottleneck has not adversely affected the persistence of European starlings in this country.

European starlings are generalists in the food they eat and habitats they use. Furthermore, European starlings tolerate human-modified landscapes, and proximity to humans- habitats that many native species are driven from. European starlings are aggressive and gregarious and easily compete with native birds for resources. They form huge flocks (up to a few thousand birds), to feed and roost, and they have a high tolerance to nesting in close proximity to one another.

European starlings tolerate suburbs and urban areas and flourish with conventions like lawns. They do really well foraging in lawns, much better than native birds like American robins that people commonly see feeding in lawns (one of the few native birds to do so). One of the main reasons European starlings do so well in lawns, is that they excel at excavating worms and insects out of the tightly woven turf grass. Their jaws have remarkable strength for opening (as oppesed to closing), and this makes them adept at opening a hole large enough in turf to remove worms and insects. By providing a lawn, this is one of the few species that will benefit.

Because they are so abundant, and good insectivores, there is the misconception that European starlings are great “biological control” agents and can be used to control insect pests in agricultural settings. But because they are such generalist feeders, they will not just eat "pests" but also important agricultural crops like grapes, olives, and tomatoes. In Australia, where they were introduced for pest control, European starlings now threaten the country's economy and biodiversity.


  1. Ok, so I convinced my husband to leave the Flickers alone and only use "squirell control" on the starlings. He seems good with this. A major step forward for a born and bred Idahoan. (who met and married a Californian... huge adjustment for him. He's learning:)
    Thanks for the good info, I have always enjoyed the flicker, now I fell like I know quite a bit more about them.

  2. I am excited to have found your blog. I am also a Missoulian and I was searching google for a landscape blog to help me understand designing outdoor spaces with native plants.
    I hope that by reading through your blog posts I'll figure out the hardest part...where to start.
    Thanks for the inspiration and information,

  3. Cassidy,
    Thanks for your comments- I hope you find my blog useful. This May I will be teaching a class at the Montana Natural History Center on garden design and landscaping with native plants. I'll post the details when I have them, but if you are interested, conatct the MNHC to sign up and for more information.
    Thanks again,

  4. Hi Heather,
    Glad you liked to post and great news that your husband is on board. Let me know if you or he need any more tips dealing with starlings or squirrels.
    Good luck with your new tomato cages, I've abandoned various cages in favor of some wooden frames (like sunflower cages). They are visible in a couple of pictures, one in the post "how to create space in a small yard".
    Thanks again for the comments.

  5. It's very cool to see others "gardening where they are" - I think I'd be so sad if I had to leave California, but then I realize I'd just start gardening in the place I ended up. It's all good, as they say.

    I remember going to see the Christmas lights in Glasgow as a child, and the tremendous omnidirectional twittering of millions of starlings clustered all along the wires, keeping warm. We have some here in the Bay Area too and yet they are not so common, in my experience - I always do a double take when I see one.

  6. Interesting information, we live in suburban Pugetropolis and we'd like to encourage our local Northern Flickers.

  7. Dear David,
    Greetings from New Zealand. And interesting commentary on starlings. When I arrived in NZ in 1970's starlings were actively fostered by pastoral farmers to control grass grub (a native moth, Porina). That fostering has fallen away, perhaps compaction of the soil is the problem for the grub. In the north, Indian Mynas (Acridotheres tristis)are displacing starlings and causing more ecological problems. In my Dunedin garden they are competiors for nectar and fruit as well as being unwelcome lodgers in the house. Death is the only stopper to a nesting starling, they are so detemined. I have found a dummy nest box trap is very effective because although there are they are in large social flocks, the flock notices the distress of the trapped starling and abandon the property. Catching a few a year is all that is necessary. Not sure how you would avoid trapping other hole nesters like your flickers. Maybe rely on the greater boldness of the starling leading it to a trap site closer to the house. A live trap, so any non-targets can be released.

    I was surprised that you make no mention of rats. Feeders, compost heaps and pet food cause rats (Rattus rattus and R. norvegicus) to flourish in the NZ urban setting. Do squirrels hunt rats? Or is your environment vole habitat?

  8. Hello Everyone,
    I would loe to invite you to my Facebook Northern Flicker Awareness Group .... I created this group in hopes that we can be heard and gather information about the ongoing battle these amazing creatures have to go through with the Starlings for their nestin sites! Please join us and let us be heard :-)!/groups/515612818475653/