Date: 3/15/25 1:03 pm From: Don Morrow <donaldcmorrow...> Subject: [NFLbirds] SMNWR Duck Season
*“They've got the urge for going and they've got the wings to go.” *
Joni Mitchell *Urge for Going* 1966
Although ducks migrate through St. Marks NWR from August through early
June, I survey duck populations on the interior pools and ponds at the
refuge from late October through mid-March. Outside of my monitoring
period, it’s mostly just Blue-winged Teal, most of which winter in South
America and have a longer migratory period than other duck species.
With most birds, a change in day length is the main trigger that gives
them the urge for going. This causes hormonal and behavioral changes that
lead to migration. Some bird species respond by preparing for, and leaving,
on their migratory journey. These are sometimes called calendar migrants,
because their migration timing is closely tied to calendar dates. They are
long distance, usually intercontinental migrants, like Pectoral Sandpipers
and Scarlet Tanagers.
However, for other species migration timing is strongly influenced by
weather. They are shorter distance, primarily intra-continental migrants
and are called weather migrants. Ducks are classic weather migrants. Fall
migration for ducks can be delayed in warmer years when they take advantage
of good weather to put off their Southbound migration. Spring migration is
tied to competition for favorable nesting territories and ducks usually
leave on time in the Spring, but may leave early.
Because weather affects migration timing, duck numbers at the refuge can
be volatile. I have a graph that shows the median number of ducks on the
refuge surveys over the preceding five-year period. This smooths out
year-to-year weather perturbations and allows me to see the annual pattern.
I can then compare it to the current year to see whether ducks are coming
in early or late and whether they are in higher or lower numbers than usual.
Attached is the graph showing this year’s duck season at the refuge
overlaid on the five-year median.
It shows that a moderately warm Fall delayed migration into the refuge, but
that winter numbers jumped up to normal levels in December. Duck numbers
stayed high through mid-February, a time at which they have usually dropped
by fifty percent or more. The mid-March duck survey logged only 188 ducks,
an eighty-seven percent drop in the last month down to a seasonally
appropriate level. Their delay in leaving was unusual. It coincided with
extreme winter weather across most of the country, which may have been a
contributing factor.
Twenty-six waterfowl species were recorded at the refuge this winter and
there were just over two thousand ducks at the high point in mid-December.
Snow Geese stayed late into the winter and we had a single Canada Goose
sighting. Canada Geese once wintered on the refuge in the thousands. A
warming climate has led them to winter further North, but we often get
strays. All three species of scoters; Black, Surf and White-winged, were
seen in the nearshore waters near the lighthouse, as was a female
Long-tailed Duck. Thirty-five Canvasback and one hundred and four Ruddy
Duck were on Lighthouse Pond in January, high numbers for both of these
species. American Black Ducks were on the refuge, continuing an unbroken
winter record at the refuge. St. Marks NWR is the only spot in Florida
where black ducks regularly winter. This year was a good duck year.
Each duck season at St. Marks is both an echo of all previous years and a
unique experience in itself. Winter is turning into Spring and ducks have
gotten the urge for going. Come down to the refuge to see the last of them
before they’re gone for the year.
