Tuesday, September 30, 2014

Hawk Ridge count summary, week of 23-30 September 2014

Most of the last week has been warm with clear skies and southerly winds, but good numbers of Sharp-shinned Hawks and other early season species have been moving through anyway, including 863 Sharp-shinned Hawks, 95 American Kestrels, and 16 Peregrine Falcons on the 28th when the temperature hit 80 degrees! What cues do these birds use to migrate? Did they “know” about the approaching front the next day on the 29th (when winds shifted to the east and temperatures stayed in the 40s)? The pressure was not sharply decreasing, and conditions were similar well to our north where the birds were likely coming from. The longer I watch migration, the more of a mystery it becomes.

juvenile Northern Goshawk flying in front of the counting platform at Hawk Ridge. Despite being the signature species for Hawk Ridge, with more typically seen here than anywhere else in the country, relatively few goshawks have been seen at Hawk Ridge thus far.
The last two days on 28-29 September have featured massive flights of non-raptors, but each day was vastly different. On Sunday the 28th an overwhelming but more enjoyable flight surprised us on a day with clear skies, calm wind becoming southwest, and temperatures hitting 80 degrees, while the flight on the 29th was an exercise in futility and frustration as uncountable thousands of birds breezed through during the passage of a front, with heavy overcast skies and temperatures only in the 40s. These birds on the 29th were riding a strong northeast tail wind, putting them way too high overhead to spot efficiently against the heavy overcast sky, and so likely many thousands of birds were missed. It is difficult to stress just how many birds were likely moving during such a mass migration event. An interesting report from Dan Nolfi doing radar research on migrating birds up at Little Marais indicated the magnitude of migration seen on the morning of the 29th was unusual for daylight hours, so I believe this morning flight was a rare glimpse at what it potentially looks during nocturnal migration at the peak of migration. The total number of birds counted on these two days included 6125 robins and 8315 warblers on the 28th, and 1603 Canada Geese, 2617 robins and 7712 warblers on the 29th. The majority of warblers being seen now are Yellow-rumpeds. This two day total of over 16,000 warblers brings the total number of warblers counted this season to over 38,000, which is the best season since these non-raptor counts started in 2007. The highlight of the flight on the 28th was a remarkable number of Yellow-bellied Sapsuckers bombing through, with a total of 98 counted, which is the highest count for Hawk Ridge, and the second highest count for the state. Smaller numbers of Blue Jays, Cedar Waxwings, Rusty Blackbirds, Common Grackles, Purple Finches, Pine Siskins, and American Goldfinches have also been mixed into these waves of birds. The migration is switching over from early stuff like mixed warblers, Blue Jays, Cedar Waxwings and Red-winged Blackbirds, to later arrivals such as American Crows, Rusty Blackbirds, American Robins, and Pine Siskins, which will dominate the flight in October. A few flocks of Cackling and Snow Geese have finally showed up, and on the 29th we saw 4 adult Ross’s Geese flying right out in front of the overlook with 6 Snow Geese.

A White-throated Sparrow engaging in redirected migration after sunrise, or "morning flight". This bird was part of a record flight of White-throats last week, including 2166 on September 21st and 4034 on September 22nd. This is by far the most White-throated Sparrows we have counted in morning flight. Although most of these migrants were flying low to the ground, some flew up over the trees such as this one. 
Another view of a White-throated Sparrow in active morning flight
immature White-crowned Sparrow migrating over the trees in early morning sunlight
An unusual view of a White-throated Sparrow flying overhead!
A more typical view of a White-throated Sparrow, this one at the Hawk Ridge feeder in front of sumacs in full fall color
photos and story by
Karl Bardon
Hawk Ridge Count Director

No comments:

Post a Comment