Biologists pose numerous hypotheses for the bluebill population decline. One hypothesis purports that contaminants -- specifically chromium and selenium -- are "bioaccumulating" in female bluebills and impacting their survival, reproduction and, ultimately, population growth.
Students at Winona Senior High School, read the latest research on contaminants in migrating and breeding bluebills and wondered how these contaminants got into scaup habitat. Growing up along the Mississippi River in Winona, the students learned about water quality testing for these contaminants and proposed for our high school science projects that bluebills might be eating contaminated invertebrates.
To test the hypothesis, they collected thousands of invertebrates from wetlands and waterways in Iowa, Minnesota, North Dakota, South Dakota and Wisconsin. These included invertebrates commonly consumed by scaup such as scuds, midge larvae, fingernail clams, snails and exotic zebra mussels.
The results were surprising. Zebra mussels, known for their water-filtering ability, contained low concentrations of chromium and selenium, while amphipods contained the greatest concentrations of chromium. They also found fingernail clams to contain alarming levels of selenium, exceeding the environmental quality threshold for these invertebrates. Wetlands surrounded by more developed land harbored invertebrates with increased concentrations of chromium and selenium.
So what does this mean for bluebills? We don't understand the full consequences of contaminants yet, hence research must continue. For example, we need a better understanding of the distribution of wetlands with environmental contaminants, when bluebills are consuming contaminated invertebrates and whether this foraging is impacting scaup survival and reproduction.
Indeed, improved habitat -- and greater availability of invertebrate foods -- can help "heal" duck and other wildlife populations and stimulate population growth.
Fellow hunters, we need to ask ourself a question: Does the world really need chromium, selenium and other heavy metals in our lives?
We may not have a resource to enjoy in the future if as a society we create man-made substances faster than they can be broken down naturally (or in the case of many toxic substances such as dioxins, DDT and PCBs, they may never break down but continue to become more concentrated in the animals that digest them).
In my opinion, it doesn't matter whether the companies that make these substances feel that they are safe or not. That misses the point; we simply cannot add something to our world if it cannot break down safely and naturally. Otherwise, you get what we have here which are substances that never existed in the diet of the bluebill before, now readily persist. The result is higher and higher concentrations of a foreign matter in the food chain and who wants that?
Certainly not me, because I not only have a passion to hunt bluebills, I also eat duck. And who wants to eat something that has concentrations of man-made substances?
Whether the question of declining bluebill populations is a resource conservation issue or not, also misses the point. Its clear to me that we cannot pursue a sustainable path with regard to our natural resources if the breeding and feeding resources for bluebills are being depleted or degraded faster than they can be re-generated naturally or the ecosystem is manipulated in favor of other priorities (such as altering wetlands for development).
I wish we could all agree that our world needs to change how we address these problems. Spending research money on what factors may be attributing to the decline of duck species like the scaup is pointless, because whatever is ultimately agreed upon as a cause will be countered with someone saying these substances or these practices are safe and cause no harm.
Unfortunately, in the end NO consensus will be reached and in the case of the bluebill, whose populations have been declining since the 1950’s, not much has been done to help them.
In my opinion, there must be some truth about the declining population of the bluebill, and any other duck species for that matter, that everyone can agree on.
There must be some truth that everyone can agree upon whether you are a farmer, a hunter, a chemical company executive or a building developer and perhaps this is it:
1. It seems to make common sense that man cannot create a new substance if that substance cannot break down faster than the natural alternative it is trying to replace.
2. It also seems to make common sense that the natural resources for ducks cannot be depleted or degraded faster than they can be re-generated naturally.
If we could agree upon these two principles as our fundamental policy on how we address all environmental matters, do you reasonable believe the bluebill populations would continue to decline?
My gut instincts tell me that all duck species would improve.
What are your thoughts?