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Currently there is a campaign to eradicate the European Starling from North America because of its threat to other species. Are there actual data regarding the extent of the ecological risk to native species, and are there data on the effects of the current eradication programs (are they working)?

Background

In North America, there an estimated 140 million European Starlings, or about 45% of the global total. The species was introduced to the continent over 100 years ago when only 120 or so were released in the New York area. Those few have quickly spread across the whole continent, competing easily with other native birds of similar type, especially for nesting holes, because they are naturally far more aggressive. It is currently listed in the IUCN List of the world's 100 worst invasive species. Annually, the US kills over 1 million of them with the sole purpose being extermination. There is even a specific poison commercially available. However I am having difficulty finding data to show how invasive the Starling really is in North America and the extent of the ecological risk to native species because of their presence. I would also be interested in data showing the impact of current control methods (do they actually reduce the impact on native species?).

fileunderwater
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    Australia has also taken great measures to eradicate the species from their country. –  Apr 11 '17 at 21:38
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    For the record, I shoot Starlings all the time. Just got one today. First of the season, which prompted the question (should I actually be doing this?). I'm fairly confident the US killing of 1 million of them doesn't bother me. –  Apr 11 '17 at 23:31
  • @fredsbend: Perhaps surprisingly, starlings are edible, and supposedly quite tasty. – jamesqf Apr 12 '17 at 06:00
  • @james And about three bites each. –  Apr 12 '17 at 06:11
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    These control measures usually are extremely ineffective and unnecessarily brutal towards the introduced species. Ecosystems change for various reasons, humans introducing species is just one of them. It is an idiotic idea to kill European Starlings in order to putatively benefit local species to give them an artificial fitness advantage. – AlexDeLarge Apr 12 '17 at 15:27
  • @Alex Are you saying there's no inherent value in preservation? Exotic species have caused the extinction of native species in the past. –  Apr 12 '17 at 15:52
  • Yes, that's exactly what I'm saying. Either you don't introduce new species or you have to live with it. There is no inherent reason for artificially selecting a 'native' species over a 'migrated' species, especially if this involves mass killings of innocent lives. – AlexDeLarge Apr 12 '17 at 16:04
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    @Alex I think you might be letting an emotional response (mass killings of innocent lives?) affect your conclusions. That's a little to close to philosophy rather than biology. Science is amoral. The question is about the Starlings impact and whether control methods mitigate that. Whether we should attempt mitigation at all is not a biology question. I must confess, your opinion on this is the first I've heard like it. I take it as a given of preservation practices that invasive species that negatively impact native species must be controlled. –  Apr 12 '17 at 16:12
  • @fredsbend: Well, people eat shrimp, which are usually less than one bite each :-) – jamesqf Apr 12 '17 at 18:18
  • @AlexDeLarge: What of the "innocent lives" destroyed by the starlings? – jamesqf Apr 12 '17 at 18:19
  • @jamesqf: It is not an emotional response. It is rational ethical reasoning. Starlings are not able to reason morally. Additionally, I am not aware of any 'successful' population control measure. – AlexDeLarge Apr 12 '17 at 18:25
  • @Alex "I am not aware of any 'successful' population control measure." Great. That's the start of part of an answer. The rest of your comment is a value judgement, and distinctly outside of the domain of biology. –  Apr 12 '17 at 21:12
  • That's why I commented and did not write an answer (even though as a biologist I do believe that ethics of biology are within the domain but we should leave it at that). :) – AlexDeLarge Apr 12 '17 at 21:34
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    @AlexDeLarge NP. I found an interesting claim: "About 42% of the species on the Threatened or Endangered species lists are at risk primarily because of alien-invasive species." Is this not concerning to you, that nearly half of endangered species are because we've introduced foreign species? –  Apr 12 '17 at 21:36
  • Related question with a good answer: Do invasive species cause long-term damage to ecosystems they invade? –  Apr 12 '17 at 21:37
  • @AlexDeLarge: Where did I say anything about an emotional judgement? It's simple fact: starlings are not herbivores: they eat other creatures, thus destroying "innocent lives". In addition, they displace other species from similar ecological niches, destroying the lives of those creatures. – jamesqf Apr 13 '17 at 04:14

1 Answers1

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First, for the record, I do not know the North American Starling situation well. However, I know of one study (Koenig, 2003) that failed to find strong effects of Starlings on other cavity nesters (i.e. looking at effects from cavity competition). When trying to control for other effects, only one species was potentially negatively effected by Starlings.

Starlings cause quite large economic effects though (Linz et al, 2007), and it wouldn't surprise me if this is the main reason for the control measures. The paper refers to a previous study which estimates that Starlings cause crop damage costs of \$800 million/year as well as \$800 million/year in health costs, due to disease transmission to livestock and humans (both figures from Pimentel et al., 2000).

So my feeling, based on a couple papers and some quick searches, is that the ecological impacts are uncertain (or to a large extent unknown) but that the economic impacts are quite large. Given the North American population sizes of European Starlings it would however surprise me a lot if there weren't any ecological effects on other species (negative and positive). These issues are hard to study though, especially without long-term data of high quality.

fileunderwater
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  • Very good point. I did not think of the economical impact being the motivation for control measures. I'm surprised that I didn't, considering most control measures are economically motivated, or at least, environmentally motivated control measures remain underfunded and under implemented. –  Feb 28 '18 at 15:25
  • Yes, that might explain the control measures. Since they are on the IUCN top-100 list I would have expected them to also cause well-known ecological problems though. Maybe there are other papers or reports that show this. In the ones I've seen (after brief searching) it is mostly the study by Koenig that is cited though. – fileunderwater Feb 28 '18 at 15:39
  • Giving the selection now, but welcome future answers to attempt a steal. Thank you for the answer. –  Jan 04 '23 at 00:01