It was a no-brainer, or so it seemed.
The sea level was rising on the Georgia coast, and their little nests were being lost to flooding. There appeared to be one option: move.
But it’s not quite that simple for the state’s population of about 30,000 seaside sparrows. Moving their nests to higher ground in the marsh turned into a debacle for parents. It allowed predators — raccoons, grackles, fish crows, marsh rats — easy access to eggs and squeaky hatchlings.
“Seems like whenever an egg was in a nest, there was a raccoon there ready to grab it up,” said Elizabeth Hunter, a researcher who observed the birds. “It seems that there are different predators, and they are more abundant than ever.”
Hunter’s study, published Wednesday in the journal The Condor: Ornithological Applications, found that the feeding frenzy isn’t exactly natural to the coast. The various predators followed coastal development, attracted by all its human garbage, which led them to the marsh and, finally, fresh sparrow eggs and bite-sized babies. Hunter said that hopefully her research will call attention to this unintended consequence of expansion and prompt improvement in waste disposal and pickup.
The study started in 2012, when Hunter was a doctoral candidate at the University of Georgia; she now is at the University of Nevada at Reno. But it could not determine if the floods that led to the feast had an impact on the seaside sparrow population. Stay tuned, she said. Development doesn’t appear to be stopping.
Coastal Georgia is the primary spot for seaside sparrows. But subspecies can also be found in North Carolina, South Carolina and Florida. As things stand, it’s just awful right now to be a sparrow and a parent in soggy coastal Georgia.
By nature, these sparrows build their nests low in the marsh grass, where they can’t be seen. Imagine their sorrow when they return to nests that are soaked and eggs that have vanished, floating somewhere on a tide — or under it.
Going higher seems like an easy fix. But the animal kingdom is rife with peeping Toms, animals that poach eggs and fledglings that take 10 days after hatching to be strong enough to fly. In a dog-eat-dog world, this happens when parents are out snatching up insects to feed their young in a habitat where everything is trying to fill its belly.
Observing their plight in the field, it seems Hunter felt sorry for the sparrow parents. “They don’t have that many choices.” And for the sparrows that perish. “If it floods, they’ll drown. Predators will eat eggs, nestlings and fledglings if they catch them.”
The Georgia marsh is wide and flat, and sparrows prefer to build nests a meter from the ground. There, chicks can hatch and remain as still as possible, as not to be detected. Any higher, and it can be movie night — “Guess Who’s Coming to Dinner,” starring the offspring.
“Nests closer to the ground are less vulnerable to predators,” the study says. For seaside sparrows, it continued, “higher nests were more likely to be depredated.”
Hunter took on the study alone, as part of a dissertation. “I was looking at the effects of sea-level on marsh birds,” she said. With a small, guilty laugh, she added that she never really cared much for sparrows, seaside or otherwise, as a researcher, until their plight came into focus. “I was realizing that predation was a bigger cause of nest failure” than sea-level rise.
As scientists and conservationists consider the effects that climate change is having on migrating birds, this is a consideration. “Sea-level rise is going to be a huge problem, but we have to consider the threats that species are having like predation.”