Spring is a time of boom and bust migration here in New Orleans. According to reports, there is a little "boom" happening today in the Couturie Forest on Harrison Avenue in City Park- the city's premier migrant trap. James Beck reported today that he and a handful of companions found 15 warbler species, accompanied by numbers of other passage migrant species, including 20+ each of Red-eyed Vireo, Great Crested Flycatcher, Scarlet and Summer Tanagers, Rose-breasted Grosbeak, and Indigo Bunting. Warblers were let by 15 Bay-breasted, 12 Tennessee, and 3 of the hard-to-find Cerulean and one harder-to-find "Brewster'" Warbler (Golden-winged x Blue-winged hybrid).
Because winds are still from the northerly half of the compass, chances are that many or most of these birds will hang tight and still be there tomorrow- continuing migration would require departure into a head wind. All these species migrate at night. If you go, focus on both the live oaks and whatever fruiting mulberries you can find in more open sunlit areas.
This fallout is a puzzling. At first glance it appears sensible- we know cold fronts precipitate fallouts by inducing birds to stopover instead of passing over us, and one came through last night. However, this front was still hours away when the birds would have arrived across the Gulf yesterday. This arrival is typically around mid afternoon, and the front didn't reach us until around 3 AM- about 12 hours too late to hit the birds with a headwind and induce them to ground. There was no rain ahead of the front, so that couldn't have caused them to stop. Could it have intercepted last night's flight instead? No- James reported the fallout as already underway at 930 am, before birds from last night's flight across the Gulf should have reached us.
Just when you think you have migration figured out! Sheesh.
Thursday, April 27, 2017
Monday, April 24, 2017
This morning I stepped out my front door to see seven large birds wheeling above the trees across the street. It was a Mississippi Kite pursued by six Black-bellied Whistling-Ducks that were equal it in size (and I am sure quite a bit heavier).
I have seldom seen a Mississippi Kite mobbed by anything- there is little reason to, since they eat insects and have unimpressive talons. Mobbing is usually engaged by birds against larger species that pose a predatory threat. But these six whistlers were on its case in a major way, tracing its circles and keeping on its tail.
I pulled out my phone to take a video, but it took too long to go through its booting steps. The birds moved south and were blocked from sight. Aargh!
Mississippi Kites are a common and widespread nester throughout residential New Orleans, wherever there are trees of sufficient stature to nest in. From now through August, they will be the most common raptor in our urban skies- with the possible exception of the two vulture species, in some parts of the city. They are one of our last migrants to return from the tropics each spring. The first I saw in my hood was yesterday.
Black-bellied Whistling-Ducks have a puzzling history here in New Orleans. They had been gradually expanding in our direction from Texas for decades, and had reached south-central Louisiana. Then, a few decades ago, they seemingly jumped eastward over lots of potential habitat and suddenly established a presence in, of all places, Audubon Park. Before long there were thousands loafing in the lagoons there. They have continued to expand throughout southeast Louisiana. While still reported in largest numbers at urban sites, they are becoming a common site in our rural surroundings as well. They have taken to nesting in residential areas of the city, presumably in tree cavities. The birds harassing the kite this morning were presumably local nesters in my hood.
On a different, but important, note: The next two weeks are usually the fortnight with the highest volume of bird migration through our area in the spring. How many of the birds will land rather than passing over will depend on the weather- a cold front usually provides the best birding.