Cape May Raptor Banding Project 40+ Years of Conservation through Banding

1. Cape May Raptor Banding Project 40+ Years of Conservation through Banding Cape May Raptor Banding Project, Inc. Cape May, NJ, U.S.A. CapeMayRaptors.org September 24, 2010

2. Introduction We have operated a raptor banding station every year since 1967 near Cape May, New Jersey, U.S.A. In 1999 we incorporated as the Cape May Raptor Banding Project, Inc. (CMRBP), a 501c3 non-profit organization run entirely by volunteers. As of 2009 the project had captured about 132,000 diurnal raptors of 16 species during fall migration in the months of September, October and November. This makes CMRBP the largest raptor banding project in North America and one of the largest in the world.

3. Location of the Cape May Raptor Banding Project

4. Methods From one to five banding stations have been operated annually at CMRBP using a combination of bow traps, mist nets and dho-gaza traps employing live rock pigeons, starlings and house sparrows as lures. Trapping methods have been described previously (Clark 1970, 1976, 1981). Habitats at stations range from agricultural fields and meadows to scrub-shrub to tidal and non-tidal wetlands. Blinds and trap/net arrays are generally oriented towards the north and/or east to take advantage of typical flight lines at Cape May.

5. Overall Banding Results Datasets maintained by the project include birds first banded at Cape May (bandings), Cape May-banded birds that return to Cape may in subsequent years (returns), encounters elsewhere of birds originally banded at Cape May (recoveries), and birds originally banded elsewhere that are encountered at Cape May (foreign recoveries). Most raptors captured at Cape May have been unbanded; fewer than 300 of the total of 132,000 have been foreign recoveries, and only about 45 captures have been returns.

6. Slightly more than half of the birds captured at Cape May have been Sharp-shinned Hawks (Accipiter striatus). Cooper’s Hawk (A. cooperii) and American Kestrel (Falco sparverius) together constitute another 30% of the total; no other single species represents more than 7%.

8. Annual totals for all species have topped 5,000 birds on five occasions, the last time occurring in 1987. The decline in annual totals since the 1970’s and 1980’s is due to sharp decreases in numbers of Sharp-shinned Hawks and American Kestrels.

10. Highlights include the second North American record of Eurasian Kestrel (F. tinnunculus) (Clark 1974a), and confirmation of the occurrence of Swainson’s Hawk (Buteo swainsonii) in New Jersey (Clark 1974b).

11. Long Term Trends Long term trends in banding numbers at Cape May show a variety of patterns. These may indicate actual changes in populations, but could also reflect shifts in migration pathways. Such shifts could result from year-to-year irregularities in weather, the influence of natural succession or increased residential development on the Cape May Peninsula, or other factors.

12. Banding numbers have been demonstrated to correlate closely with similar trends in Cape May Hawk Watch counts for Northern Harrier (Schultz 1996). Numbers of birds banded appear to track Cape May count trends for other species too, including declines in Sharp-shinned Hawk and American Kestrel since the 1970’s and 1980’s, and increases in Cooper’s Hawk and Peregrine Falcon (Falco peregrinus) over the last 30-35 years (Bildstein, et al 2008).

17. Age and sex ratios Of those that could be aged, 94% of birds banded were aged by plumage as juveniles (hatch year), while only 0.6% were definitively aged as full adults (after second year). Sex ratios frequently deviate from 1:1, with some species, such as Cooper’s Hawk, Northern Goshawk and Northern Harrier, showing ratios of nearly 2:1. Sex ratios of recoveries vary from those of bandings, with no discernable relationship between the two.

19. Migration Timing Generally, falcon captures peak in late September; accipiters, with the exception of Northern Goshawk (A. gentilis), in mid-October; and buteos, chiefly Red-tailed Hawk (B. jamaicensis), in early November.

21. Within most species, seasonal timing of captures differs noticeably by age class, with juveniles peaking before adults. The statistical significance of this difference at Cape May has been confirmed for Northern Harrier (Circus cyaneus) (Bildstein et al 1984) and holds true for other species as well.

26. Differences in timing by sex are less consistent. Analysis of Cape May data shows that females migrate earlier than males for Merlin (Falco columbarius) (Clark 1985). This is partially or completely true for Sharp-shinned Hawk, Cooper’s Hawk and American Kestrel as well. However, this tendency is reversed for Northern Harrier (Bildstein et al 1984), where males migrate first.

27. 28 September

32. Summary of Recoveries About 2,500 Cape May-banded birds (2%) have been encountered subsequently at other locations throughout the Americas at all times of the year. Most recoveries are from the Eastern U.S. and the Canadian Maritimes, although there are some records from the West Indies and Central and South America.

33. Recoveries of Cape May-banded birds

34. Encounter frequencies differ from capture rates in most species, with larger species encountered relatively more often than smaller species. This is probably the result of an increased probability of detection of larger birds.

36. Movements Mapping of encounter locations shows that summer ranges – and therefore, presumably, breeding areas – for many species are primarily northeast of Cape May.

37. Summer recoveries of Sharp-shinned Hawk

38. Summer recoveries of Cooper’s Hawk

39. Summer recoveries of Red-tailed Hawk

40. Summer recoveries of Merlin

41. Summer recoveries of American Kestrel

42. Mapping also demonstrates possible seasonal differences in migration pathways, and possible differences between sexes in breeding and wintering ranges, for some species. For example, Sharp-shinned Hawks and Cooper’s Hawks appear to migrate further inland in the spring than in the autumn, and female Cooper’s Hawks winter further south, on average, than males.

43. Spring and Autumn recoveries of Sharp-shinned Hawk

44. Spring and Autumn recoveries of Cooper’s Hawk

45. 39.17° 37.98° Winter recoveries of Cooper’s Hawk

46. Finally, about 6% of recoveries were made north or west of Cape May within several weeks of the banding date, indicating that fall migration does not always progress steadily southward.

47. Same-season recoveries north of Cape May

48. Longevity Longevity records for raptors banded at Cape May, derived from recoveries, include 24 yrs for Red-tailed Hawk, 15 yrs for Northern Harrier, Sharp-shinned Hawk and Cooper’s Hawk, and nearly 14 yrs for Broad-winged Hawk (B. platypterus).

50. Mortality Of encounters listing a specific cause of mortality, collisions with moving vehicles account for about 30% and collisions with stationary objects about 25%.