FIFTH FLYWAY
| By Joe Genzelin drier years, those larger bodies of
water are more likely to remain, giv-
ing gadwalls abundant nesting and
brood-rearing opportunities.”
Other research conducted by the
USGS Northern Prairie Research
Center points to changes in weather
patterns. Anteau says large, sudden
precipitation events are occurring
more frequently, which is also result-
ing in larger bodies of water.
“We can’t say for sure that the
increase in the number of larger bodies
of water in the Prairie Pothole Region
is resulting in more gadwalls. This is
all very speculative,” he adds. “We
are just lining up what we know and
using that to speculate some of the rea-
sons gadwalls are doing so well. The
increase in the number of larger ponds
may certainly be playing a role.”
Even Northern shovelers have
become a staple among waterfowlers
throughout the Mississippi, Central
and Pacific flyways thanks to boom-
ing populations. There were 4.2 mil-
lion breeding birds in 2018, which was
42 percent above the long-term aver-
age, according to the USFWS. And
like gadwalls, that success may be a
result of changing conditions.
“Shovelers eat a lot of water fleas
and we know that water fleas are
highly abundant in low-quality wet-
lands that either have high nutrient
levels or less diverse aquatic plant
communities,” says Anteau. “Again,
that is purely based on speculation,
but the evidence suggests changes to
wetland quality have helped some
species and probably hurt others.”
THE FOX DECLINE
Rohwer says one more factor appears
to be helping some species have high
nest success and brood survival rates:
Mange. The disease has knocked
down fox populations throughout
the Northern Plains states. Mange is
highly contagious among foxes and
some other mammals and spreads
rapidly when mammal populations
are high.
“Red foxes have essentially fallen
out of the system in the Northern
Prairie. They are heavy duck preda-
tors. In fact, they are by far the worst
duck predator on the landscape. They
kill nesting hens and they cache eggs.
Basically, if they find an unoccupied
nest, they will take the eggs some-
where else and hide them. Those eggs
won’t hatch,” he says.
One estimate from 1996 suggested
foxes kill upwards of nearly 1 million
nesting hens each year. That was
about the same time fox numbers
started to slide. Although Rohwer
doesn’t know of any recent studies
that have examined current fox popu-
lation trends, he and other biologists
who work in the PPR just don’t see
them much anymore.
Coyotes may also be playing a role
in the decline of red foxes, as well,
says Scott McLeod of USFWS. The
larger predator either kills red foxes or
displaces them, pushing them closer
to towns and other human-inhabitedlocations. Coyotes do eat eggs and
ducklings, but they are generally not
considered a significant nest predator.
“There seems to be more coyotes
on the landscape where I work,” he
says. “When we increase grassland
acreage, we increase coyote habitat.”AG DIPS HELP DUCKS
Thanks to a growing demand for
conservation programs, grassland
acreage continues to inch upwards in
some places. Although CRP acreage
continues to lag, McLeod says other
private lands conservation programs
are in high demand in the Dakotas.
“Recent drops in commodity prices
have more landowners seeking alter-
native ways to make money on less
productive land. Easement programs12 WILDFOWL Magazine | September 2019 wildfowlmag.com