Yearly Count Charts

TV 2017Turkey Vultures are expanding their range northwards, and that is why we’re seeing more and more every year.

B Eagle 2017Bald Eagle numbers continue to increase, but are not as high yet as they were 100 years ago.

Osprey 2017The recent recovery of the Osprey is not readily apparent in DHBO’s numbers.

N Harrier 2017The Northern Harrier count has been fairly stable over the last ten years.

SS Hawk 2017A decrease of Sharp-shinned Hawk numbers has been observed at many northeastern hawk watches.

N Goshawk 2017The Northern Goshawk is an irruptive species whose southward movements are closely tied with prey availability. Goshawk migratory peaks reflect lows in the population cycles of its chief prey, the Snowshoe Hare and the Ruffed Grouse.

C Hawk 2017Cooper’s Hawk, Northern Goshawk and Red-shouldered Hawk all migrate around the same time of year – second half of March. The mid-nineties spike in all three species may be related to favorable March weather.

BW hawk 2017The number of Broad-winged Hawks per season depends on favorable winds in the second half of April.

RT Hawk 2017A spectacular Red-tailed Hawk flight was recorded in the mid 90s. Since then, numbers have been around the 5,000 mark.

G Eagle 2017The number of Golden Eagles recorded each season at Derby has increased over the years.

RL Hawk 2017To some extent the Rough-legged Hawk is an irruptive species whose numbers vary over the years. A cyclical pattern emerges that is probably related to prey species abundance.

RS Hawk 2017The Red-shouldered Hawk count has shown a very gradual decrease over the years.

A Kestrel 2017The American Kestrel is declining in the northeast. The 2005 count was the lowest on record, but numbers rebounded somewhat in 2006 and 2007. It is too early to speak of a trend reversal.

Merlin 2017Overall, Merlin numbers are higher now than they were in the 1980s and early 90s.

Peregrine Falcon 2017The Peregrine Falcon has made a healthy comeback after near-extinction in the early 1970s. Numbers at Derby Hill fluctuate because this species is not funneled along the lakeshore as much as the other species.

Looking at all species, we see a gradual decline in numbers. Bulk species such as Broad-winged Hawk and Red-tailed Hawk are responsible for this decline, which is somewhat mitigated by a rise in numbers for Turkey Vulture