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Annual counts | Distribution (time of day, week) | Changes (last 8 yrs) | Links | Articles | Sources
The Chimney Rock Hawk Watch accessible via a paved trail from the parking lot at the end of Miller Ln. off of Vosseller Ave. just north of Rt. 22 in Martinsville was started in 1990 by Christopher Aquila. Chris coordinates a group of birders which staff the site from September 1 to November 15. You can learn a lot by just standing around and listening to them call out sightings.
John Kee compiles the data at chimneyrock.s5.com which is the basis for the analysis below.
There is older historical data at www.rci.rutgers.edu/~magarell/chimney_rock/
Maps: Martinsville, Washington Valley Park
Other Links:
Current Counts at Hawk Migration Assiciation of North America's (HMANA) hawkcount.org (NJWMP at Chimney Rock)
Totals Excluding Vultures. (see yearly totals below)
| Totals * thru | 1996 | 1998 | 2000 | 2002 | 2003 | 2006 | 2007 | 2008 | 2009 |
| Sep 08 | 108 | 550 | 289 | 178 | 178 | 119 | 148 | 112 | 248 |
| Sep 15 | 1,574 | 4,354 | 1,542 | 874 | 357 | 754 | 1,269 | 990 | 4,606 |
| Sep 25 | 26,691 | 11,859 | 22,439 | 8,810 | 1,438 | 5,176 | 5,769 | 8,955 | |
| Sep 30 | 27,399 | 12,862 | 24,711 | 10,125 | 2,768 | 6,843 | 6,486 | 9,405 | |
| Oct 15 | 29,623 | 15,416 | 27,075 | 11,603 | 5,320 | 8,101 | 8,291 | 10,826 | |
| Nov 15 | 31,470 | 18,632 | 28,368 | 13,241 | 6,585 | 9,835 | 9,366 | 11,824 | |
| Nov 30 § | 31,564 | 18,727 | |
| Highest two days | | | | | | | | | |
| Day | Sep 19 | Sep 10 | Sep 22 | Sep 17 | Sep 30 | Sep 21 | Sep 15 | Sep 16 | |
| Count | 5,018 | 990 | 7,450 | 4,128 | 1,151 | 1,619 | 770 | 1,818 | |
| Day | Sep 20 | Sep 24 | Sep 25 | Sep 24 | Oct 01 | Sep 25 | Sep 16 | Sep 18 | |
| Count | 17,923 | 5,353 | 6,163 | 1,453 | 562 | 1,301 | 3,703 | 4,484 | |
* less vultures
§ Count stoped on Nov. 15 in recent years
Most of the variability comes from Sept 15-25 which usually accounts for 40-70% of the total; The number of sightings from Sept 25 to Nov 15 on the lowest year, 2003, was 3,800 and on the highest year, 1996, was 4,100.
Cape May and Hawk Mountain counts for Sept. only.
Chimney rock Sept. counts for 69-87% (Av. 76%) of the total.
See below for speculation on decline.
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Total Sightings (Including Vultures starting in 2005)
| Year | Total* |
| 2008 | 12,275 |
| 2007 | 9,411 |
| 2006 | 10,060 |
| 2005 | 8,693 |
| 2004 | 10,635 |
| 2003 | 6,214 |
| 2002 | 13,241 |
| 2001 | 9,763 |
| 2000 | 28,379 |
| 1999 | 23,075 |
| 1998 | 18,727 |
| 1997 | 18,127 |
| 1996 | 31,564 |
| 1995 | 19,545 |
| 1994 | 17,184 |
| 1993 | 20,727 |
| 5 Year average sightings per day (1997-2001)
| Week | Median/
Day | Low | High |
|---|
| Sep. Wk1 | 26 | 2 | 203 |
| Sep. Wk2 | 126 | 1 | 1933 |
| Sep. Wk3 | 213 | 8 | 7450 |
| Sep. Wk4 | 194 | 0 | 6163 |
| Oct. Wk1 | 145 | 3 | 566 |
| Oct. Wk2 | 77 | 1 | 448 |
| Oct. Wk3 | 106 | 0 | 492 |
| Oct. Wk4 | 44 | 0 | 419 |
| Nov. Wk1 | 29 | 0 | 156 |
| Nov. Wk2 | 7 | 0 | 354 |
Numbers vary widely depending on
weather.
see table to right.
|
Counts by Wind Direction (Birds/Hr.)
| W | 65 |
| WNW | 92 |
| NW | 103 |
| NNW | 146 |
| N | 19 |
| NNE | 16 |
| NE | 159 |
| E | 285 |
| SE | 4 |
| SSE | 4 |
| S | 4 |
| SSW | 2 |
| SW | 6 |
WSW | 34 |
(Weather)
|
Sources:
- Species Records thru 2005 by John Kee
- A Five Year Analysis of Autumn Hawk Migration at Chimney Rock, Martinsville, N.J. (1990-1994) , by Christopher D. Aquila & Steven B. Byland
- Species Records Page and
Flight Distribution
Pictures in Bird Watching.
Decline
Cape May and Hawk Mountain counts for Sept. only.
Chimney rock Sept. counts for 69-87% (Av. 76%) of the total.
| Species | 1996-2000 | 2004-2008 | Decline/
Increase |
| Average # | % of total | Average # | % of total |
| Broad-winged | 15,688 | 65.6% | 5,980 | 53.5% | -62% |
| Sharp-shinned | 3,876 | 16.2% | 2,458 | 22.0% | -37% |
| Am. Kestrel | 1,724 | 7.2% | 779 | 7.0% | -55% |
| Osprey | 733 | 3.1% | 468 | 4.2% | -36% |
| Cooper's | 475 | 2.0% | 467 | 4.2% | -2% |
| N. Harrier | 278 | 1.2% | 213 | 1.9% | -23% |
| Merlin | 276 | 1.2% | 197 | 1.8% | -29% |
| Red-shouldered | 242 | 1.0% | 184 | 1.6% | -24% |
| Red-tailed | 271 | 1.1% | 155 | 1.4% | -43% |
| Bald Eagle | 90 | 0.4% | 129 | 1.2% | +44% |
| Peregrine Falcon | 77 | 0.3% | 98 | 0.9% | +27% |
| Golden Eagle | 11 | 0.0% | 14 | 0.1% | +31% |
| Unidentified Raptor | 86 | 0.4% | 16 | 0.1% | -82% |
| Unidentified Acciptor | 42 | 0.2% | 11 | 0.1% | -75% |
| Unidentified Buteo | 19 | 0.1% | 5 | 0.0% | -72% |
| Unidentified Falcon | 12 | 0.1% | 5 | 0.0% | -58% |
| N. Goshawk | 7 | 0.0% | 2 | 0.0% | -66% |
| Rough-legged | 1 | 0.0% | 1 | 0.0% | -50% |
| Total | 23,909 | | 11,182 | | -53% |
Sources: chimneyrock.s5.com by John Kee
There are a variety of factors which different experts have speculated to account for the decline. I couldn't find any definitive studies.
- Weather patterns - From 1995 to 2000 Chimney Rock counts were down when Hawk Mountain counts were up. Could weather be pushing the birds further west?
- Bird flu.
- Reduction of habitat in the north.
- Global warming causing fewer birds to migrate or to winter at more northern latitudes.
- More back-yard feeders has been proposed as a cause of sharp shin declines.
- The declines vary by species and location.
- Most species have recovered from their decline in the 1950's due to DDT, loss of habitat and hunting.
See:
"Using Autumn Hawk Watch to Track Raptor Migration and to Monitor Populations of North American Birds of Prey" - Article on Sharp Shinned migration decline
State of the Birds � The 2009 Report from the Interior Dept. shows that Wetland birds are increasing while Grasland and Aridland birds are declining.
Other Hawk Watch Sites:
Counts are for Fall only.
See map at: www.rci.rutgers.edu/~magarell/chimney_rock/about_cr.html
| Site | Location | Median
Fall
Totals | 2002
Total |
| Cape May | Cape May, NJ | 50,000 | 35,267 |
| Hawk Mountain | Kempton, PA | 20,000 | 21,708 |
| Chimney Rock | Martinsville, NJ | 19,000 | 13,241 |
| Monclair | Monclair, NJ | 12,000 | 11,340 |
| Militia Hill | Fort Washington State Park, PA | 9,000 | |
| Wildcat Ridge | Hibernia, NJ | 9,000 | 7,011 |
| Racoon Ridge | Blairstown (Hemlock Glen), NJ | 15,000 | * 4,238 |
| Scotts Mountain, Merrill Creek | Washington, NJ | 9,000 | 8,737 |
| Sunrise Mountain | Stokes State Forest, Branchville, NJ | | * 4,678 |
| Bake Oven Knob | Germansville, PA | | 20,778 |
(Median 1998-2002)
* Racoon Ridge only counted for 9 days in Sept. 2002
* Sunrise Mountain only had counts for 13 days in Sept. 2002
Some sites keep Spring totals also (Feb-May) which are about 1/3 of Fall totals.
Other New Jersey sites at: New Jersey Sites, Hawk Migration Assiciation of North America (HMANA)
and the JerseyBirds mail list.
Scherman-Hoffman Wildlife Sanctuary (New Jersey Audubon Society)
Bernardsville, (908) 766-5787
Links
Bird Watching Here
Cornell Lab of Ornithology
Cornell's All About Birds
The Hawk Conservancy Trust
Chimney Rock Hawk Watch: Other Birding Sites
Data entry overload? Learn eBird tricks and tips! - eBird.org
See Also: Binoculars,
Birding and Raptors in Northwest New Jersey at www.njskylands.com
Links at main Hawk Watch Page
Bird Watching in hobbies
Squirl Proof Bird feeders
Articles
- John Kee - Species Records thru 2005
- Christopher D. Aquila & Steven B. Byland - A Five Year Analysis of Autumn Hawk Migration at Chimney Rock, Martinsville, N.J. (1990-1994)
- Kyle McCarty and Keith L. Bildstein - "Using Autumn Hawk Watch to Track Raptor Migration and to Monitor Populations of North American Birds of Prey", USDA Forest Service Gen. Tech. Rep. PSW-GTR-191. 2005
- Robyn Worcester, Ron Ydenberg - Cross-Continental Patterns In The Timing Of Southward
Peregrine Falcon Migration In North America, 2008,
- Johnd Elong, Stephen W. Hoffman - Differential Autumn Migration Of Sharp-Shinned And
Cooper's Hawks In Western North America
Sources:
chimneyrock.s5.com John Kee.
www.rci.rutgers.edu/~magarell/chimney_rock/
Return to: Martinsville Information
last updated 15 Sep 2009 |
Martinsville
(For a day with 100 sightings)