This bird has been flying all night. It started its journey somewhere in Saskatchewan, with its sights set south. The same route it took last year, the same route generations of birds before it traveled.
The black-crowned night heron is diminutive next to its great blue relative. Their black and gray feathers are part of a comparatively short wingspan. It is a hunched and stocky bird, but has a delicate white plume at its nape.
It has an erratic migration pattern, but, like other migratory birds, it is a creature of habit.
That is why, when this black-crown night heron prepared to make its usual refueling stop in the wetlands of southwestern Ohio, unexpected and newly constructed sidewalks and cul-de-sacs threw a wrench in its plans.
“Urbanization and its corresponding alteration and loss of habitat have effects on bird distribution and abundance,” former Miami University biologists Nancy Crosby and Robert Blair said in the publication, a compilation of scientific articles, “Avian Ecology and Conservation in an Urbanizing World.”
The black-crowned night heron and countless other birds are feeling the effects of new neighborhoods and shopping malls even more than the people for whom they are built.
According to US Census data, the population of the Cincinnati Metropolitan area grew 8.1 percent from 2000 to 2009. This means that, as humans expand, take up more space and pollute more, there is less hospitable habitat for birds like the black-crowned night heron. It also means the diminishing migratory stopovers, spots unscathed by urban development, are becoming more important.
Spots like Mill Creek.
“There a lot of birds that pass through this area on their way south,” Miami University biology professor and avid birder David Russell said. “We have had more and more birds stopping at areas like Mill Creek because it is there, it’s available and it has the right fuels for refueling.”
This, however, has not always been the case. Mill Creek is infamous in the Cincinnati area for having a nasty past.
“It used to be just this horrific open sewer that cut through the city,” Russell said.
The creek and the numerous conservationists working to better it are still reeling from decades of misuse. The recent urban sprawl is yet another threat. Mike Busam, former president of Gilmore Ponds Conservancy, adamant volunteer and birder, said that he has seen Mill Creek’s evolution first hand.
“I see it improving,” Busam said. “Because of the work these people are doing, I’m optimistic. It’s never going to be what it was 200 years ago, but that’s not the point. You have to do the best you can and I think the groups are doing good work.”
Russell agreed that Mill Creek does not have to return to its untouched and natural state to continue to be an important spot for migratory birds. In the past, he said, the pollution adversely affected birds’ food and, in turn, drove them away from the creek.
“Because, historically, it has been so bad that things would go there and pick up lots of toxins, having no impact is actually going to be an improvement from what it was,” Russell said.
As the food chain below the birds, such as black-crowns, becomes healthier, they will be able to further utilize the creek as a stopover point. It is imperative to continue to establish the creek as a safe source of “fuel” for migration, Russell said, because there are fewer and fewer places, healthy or not, for birds to stop.
“I think [Mill Creek] will continue becoming more important,” Russell said, “Especially as things keep building up, building up, building up.”
A group of University of Washington faculty researched urbanization’s effect on habitats and the organisms that live there and also published their findings in “Avian Ecology and Conservation in an Urbanizing World.”
“Urbanization is likely to be the single most important driver of extinction during this century,” they said. “Already, urbanization is the second most frequently cited cause of species endangerment in the United States.”
This means Mill Creek, and areas like Gilmore Ponds, close to the creek’s headwaters in Hamilton, in its watershed, are becoming the green islands that perforate Ohio’s increasing blanket of urban development.
“Fairfield used to be a rural area, it used to be all farms,” Russell said. “Now you drive through and there will be a barn with houses all around it, so the only crop that is growing are houses and condos.”
Russell said that he is already seeing the effects of this urbanization in his studies and that in a 20-year period, it is possible that the number of neotropical migrants (birds that spend the summer breeding in North America and then travel south) coming through southwestern Ohio could drop by as much as 80 percent.
“It’s through a combination of factors, all of which boil down to, they don’t have a stop that’s safe and has the right fuel,” Russell said.
At Mill Creek, in order to avoid displacing the birds and interrupting their migratory route, people must continue to establish an ecosystem conducive to stopovers.
“They could go elsewhere, but where else would they go?” Busam said. “You can’t make a new Mill Creek so they have to work with what they have.”
Essentially, a car driving through a desolate landscape in search of a gas station is in the same position.
“If you have a diesel car and you live in Minnesota, you drive around forever looking for a gas station with diesel,” said Russell. “Well the same thing with these birds driving in, if there’s not the right fuel there [they can’t stop].”
That’s what has happened to some disgruntled black-crowns, whose stopover points have become cul-de-sacs. Their migration is interrupted, their habit thrown off.
In 20 years, if the creek and all those who care for it play their cards right, a descendant of that black-crowned night heron will make the trip from Canada to the Caribbean in good condition, stopping by Mill Creek to fill up its tank.
Written by: Reis Thebault
Photo License: Creative Commons