From the Contact Station December 2021

Big Birds Abound

The swans are back in good numbers. A few arrived in late

October, but the bulk of them came in during November.  Both Tundra and Trumpeter species have been sighted now.  With all the ponds quite full, they are finding their favorite areas to feed so they are nicely distributed around the auto tour.  There is a nice selection of ducks also.  Eagles are beginning to pair and check out last year’s nests to begin rebuilding.  On the recent goose count, where we survey the whole refuge, I was able to ascertain that there are at least seven eagle nests around the refuge, and probably more I missed. For four of them, I saw single eagles fly from or sitting on the nest.  This bodes well for our eagle population.  Keep an eye out for mating behavior and gathering of nest materials in the next month. The most easily seen is the one across Lake River, just where the tour road turns north along the dike. You have to stop about 50 yards or so before the turn to see it over the dike.  Another good spot for a nest view is from the port in town. If you look across the river, there is a nest in the tree line seen over the dike.

Great Blue Herons, Ardea herodias, and Great Egrets, Ardea alba, always catch my attention. This month I was intrigued by a Great Blue and a Great Egret maybe 20 feet from each other, hunting for food on the edge of the slough along the first leg of the drive (Apologies for the phone photo. They really are there).  Obviously looking different but standing and foraging in a very similar manner.  These two birds share a lot of habitat and food preferences but don’t seem to be in competition.  Often, they can be found sharing roosts for nesting colonies.  If you go up to Woodland, just off Kuhnis Road west of I-5, there is a very tall stand of trees where the Great Blue Herons and some Great Egrets nest.  It is worth the drive during nest season. It is probably a source of some of our winter visitors.  Great Blue Herons have a nesting history on the refuge too.  It is just not along the River S auto tour.  Historically there was a colony on Bachelor Island with about 250 birds.  That colony dispersed to multiple locations around the refuge. Why? We don’t know. We probably still get about 50 nesting Great Blues in total during the summer in multiple, small colonies, but unfortunately, still none established on the auto tour.  That is not surprising though as they like isolated locations for nesting that discourage predation by snakes and mammals and disturbance from humans.  I recall a rather notorious rookery in New Jersey that was full of Great Blues, Night-herons, and Egrets at one time but was totally empty, sadly, when I visited.  Turned out Great Horned Owls had moved in nearby and were harassing the colony.  Steigerwald NWR also has had a large nesting colony. They had to be discouraged from nesting this last year because of all the construction activities having the potential to cause birds to abandon already started nests.  There were plenty of alternative sites close by. With the amazing habitat restorations there, it is hoped they will be back in the not-too-distant future to re-establish their colony.

Great Blue Herons are known to eat whatever is in striking distance including birds, snakes, crustaceans, and amphibians. The species is primarily a fish eater choosing shorelines of oceans, marshes, lakes, and rivers to forage. But it also stalks upland areas for rodents and other animals, especially in winter. we witness that on the auto tour now.  Living in New Jersey, I often visited John Forsythe NWR and I was very used to Great Blues fishing along the ponds and stream edges.  In winter, they would disappear from the refuge when the water froze.  I thought they were just migrating south, but they were probably on farm fields I had no access to. Hence my surprise to see them going after voles in our fields when I first visited our refuge.  For the Friends photo contest, we often get submissions of Great Blues or Great Egrets with their captured prey.  We’ve probably seen it all – bullfrogs, tree frogs, snakes, voles, and salamanders clutched in big bills.

Just like the Great Blue Heron, the Great Egret is an opportunist, feeding mainly on fish, but also invertebrates, particularly crustaceans in appropriate habitat, as well as amphibians, reptiles, birds, and small mammals. It has a wide variety of hunting techniques including walking slowly (its dominant technique), stand-and-wait, and peering technique. A total of 26 different techniques have been recorded also including foot stirring, foot paddling, foot probing, bill vibrating, gleaning, hovering, dipping, plunging, diving, and foot-dragging.  What an array of possible behaviors to watch.

Low temperatures, high winds, too much rain, or drought all can have a detrimental effect on colonies, having a negative impact on eggs and nestlings.  Although Great Egrets were a common and widely distributed bird during the early to mid-nineteenth century, the plume trade, primarily 1870–1910, reduced numbers in North America by >95%. By 1911–1912, the total known in the U.S. was perhaps 1,000–1,500 pairs in the southeast and California. The first year for a Great Egret is very hazardous, with jays, crows, gulls, and raptors all looking for a meal at a colony. For older birds, hazardous weather, drought, and electrical lines are more likely to take a toll.  However, the North American Waterbird Conservation Plan estimates 180,000 breeding Great Egrets continent-wide, with increasing populations that are not currently at risk.

For the Great Blues, it is estimated that 83,000 breeding adults occur across North America.  Data available for Great Blue Heron population trends is variable, however.  Although they might be holding their own, e-bird data, Breeding Bird Surveys, Christmas Bird Counts, and some other population studies show both steady-state and declining populations.  Food supply is an important factor in success for this species as are major storm events like the more frequent and intense hurricanes in the east destroying colonies.  Much like the Great Egret, eggs and fledglings can be prey to a variety of larger birds.  However, that massive stabbing bill must be an effective deterrent as only Bald Eagles have been documented taking an adult Great Blue Heron.

So, next time you see a Great Blue Heron or Great Egret on a field or along a slough, take a moment to watch their feeding techniques.  When there is a number in a field, notice how they are rarely in close proximity to each other but provide ample room to forage on their patch.

Your From the Contact Station columnist is going to take the end of December off to participate in Christmas Bird Counts, Shorebird Surveys, and Raptor Counts.  Until next year, good wishes for a friend and family-filled holiday season.

-Susan Setterberg, Contact Station volunteer