September Migration
September is one of my favorite months in the Central Valley. We start to see some cooler weather and a taste of fall. For birders, it also marks a time when some of our early migrants start to show up. The Northern Pintail has already begun arriving along with Northern Shovelers and Green-winged Teal, and I am looking forward to winter. The habitat conditions waiting for our migrant and wintering waterbirds look to be good. Water conditions are better than a drought but not as good as a wet year. Rice, a key habitat for our water birds, is abundant throughout the Sacramento Valley.
One of the things that amazes me about some bird species is their migration distances. Many of our wintering birds travel a long way to get to California’s Central Valley, however, few species travel further than our Arctic nesting geese (Figure 1.).
Figure 1. Migration paths of 3 species and one subspecies of geese as tracked by GPS transmitters from work by the USGS and UC Davis.
Arctic nesting geese aren’t the only birds to make long migratory flights. Shannon Skalos recently completed a study on Northern Harriers in the Suisun Marsh. She found that while some wintering Northern Harriers breed in the Suisun Marsh, others migrate north to nest in Alaska and portions of the Arctic (Figure 2.).
Figure 2. The migration path of a Northern Harrier with a GPS transmitter attached from work conducted by Shannon Skalos while at UCD in collaboration with the USGS.
Another long distance migrant is the Golden-crowned sparrow. A 2024 study of Golden-crowned sparrows documented a similar migration path and distance from Alaska and British Columbia to California (Figure 3. https://doi.org/10.1371/journal.pone.0305369 ).
Figure 3. Breeding locations of Golden Crowned Sparrows that were captured at UC Davis (purple), UC Santa Cruz (yellow), or at Point Reyes National Seashore (green).
Waterfowl are large enough for transmitters that provide high quality data over long periods. One of the things that allows for is an estimate of flight speed during migration. A 2019 study found migration flight speeds for 6 species of waterfowl average 33-51 mph with peak speeds of 50-85 mph (Table 1)!
The migration of these species is amazing and can be awe-inspiring, and we still have much to learn. The next time you are out this Fall or Winter and see a bird, take a moment to recognize that the bird may have traveled 100’s or 1000’s of miles to get to California!
From a birding standpoint, one of the benefits of climate change is that many species of birds are shifting or changing their migration patterns. You never know what is going to show up! Who remembers the Garganey that showed up at Bridgeway Island in West Sacramento in winter of 2019-2020, or the Black Skimmer that showed up at the Yolo Wildlife Area in 2017? What could show up this year…a Red-faced Cormorant or maybe the Narcissus Flycatcher? Let’s get out and bird!
On another note, this month I will be at the McKinley Library September 27 from 3:30 - 4:30 presenting to 5-10 year olds. Come and take an up-close look at bones and skulls, tracks and scat, nests and eggs, wings and feathers, and learn about mammals and birds and the clues they leave us. https://engage.saclibrary.org/event/11573317
-Cliff Feldheim