By Mike Britt
Three members of the family Caprimulgidae (Goatsuckers), regularly breed in New Jersey. They are Chuck-will’s-widow (Caprimulgus carolinensis), Eastern Whip-poor-will (Caprimulgus vociferous), and Common Nighthawk (Chordeiles minor), the focus of this article.
Common Nighthawk alone has nine recognized subspecies exhibiting substantial geographic variation (Poulin, Grindal, and Brigham 2011). Common Nighthawk is a crepuscular, insectivorous species that feed on the wing, flying erratically and quite bat-like over open areas and also higher in the sky. The species nests on the ground, although no nest is constructed. Breeding occurs throughout a good portion of provincial Canada and the southern sections of the Yukon and Northwest Territories; throughout the lower 48 states; parts of Central America; and thought possible but unconfirmed in southeast Colombia (Meyer de Schauensee 1970, Hilty and Brown 1986). It is considered a, “Rare summer visitor to Newfoundland with no evidence of breeding (Godfrey 1986, B. Maybank pers. comm.), accidental on Queen Charlotte I., British Columbia (Campbell et al. 1990), and rare summer visitor to Alaska (Armstrong 1995).” According to Poulin, Grindal, and Brigham 2011, “the primary winter range appears to encompass the lowlands of e. Ecuador and e. Peru, s. Brazil, Paraguay, Uruguay, and n. Argentina south to Catamarco and Buenos Aires, possibly w. Brazil, and probably Bolivia. Winter range may extend into n. South America, but most individuals probably winter from e. Peru, e. Ecuador, and s. Brazil south.”
In New Jersey, nighthawks are most commonly observed during their migration periods, at which time they can sometimes be seen diurnally. Spring migration spans from late April to early June, with the peak typically around mid-May. Fall migration runs from early August to mid-October, with the highest numbers usually in late August or early September.
Any nighthawk encountered in June and July is worth noting and close scrutiny, as this species has undergone a significant decline in New Jersey and abroad. The reasons for this decline are complex and not fully understood. Some known causes of decline are changes in roofing practices, as rubberized topcoats are now preferred to gravel and widespread use of pesticides. During New Jersey’s last breeding bird atlas (1993-97), nighthawk was confirmed in just six blocks, probable in thirty-six, and possible in sixty-five, for a total of one hundred seven blocks (Walsh et al. 1999). Most of these sites were in the Pine Barrens and the northeastern section of the Piedmont (Walsh et al. 1999). Breeding habitat according to Poulin, Grindal, and Brigham 2011, “includes coastal sand dunes and beaches, logged or slashburned areas of forest, woodland clearings, prairies and plains, sagebrush and grassland habitat, open forests, rock outcrops, and flat gravel rooftops.” However, the species can be found in almost any open or semi-open situation, so long as a suitable nest site exists. In northeastern New Jersey, I have heard/observed summering birds around industrial areas, landfills, rail yards, and so-called “brownfields.” Because of access issues surrounding such places, breeding confirmation is difficult, at best. In many cases, the best one can do is document the bird during the “safe dates.” Following is a breeding account, from the summer of 2013.
Breeding Account in New Jersey
On the evening of July 10, the male made several brief visits to nest area, calling and landing briefly. I did not see the female, so could not determine the exact nature of his visits. Looking back in retrospect, he may have been feeding the young. On July 12, I was joined by New Jersey Audubon’s Nellie Tsipoura and Michael Allen, both of whom have experience with breeding nighthawks at Lakehurst Naval Air Station, Ocean (Note: This location has been renamed several times since but will simply be referred to here, as Lakehurst). The purpose of their visit was to perform a habitat assessment, for future nightjar studies (M. Allen and N. Tsipoura pers. comm.). When I showed the researchers the nest site, the female was in a different location. Instead of being out in the middle of the rocks, she was sitting “high” in a weed-line, along the periphery of the site and appeared to have a chick at her side. Upon closer investigation, it was discovered that the female had two chicks (two eggs is almost an absolute rule with Common Nighthawk), as she flushed and performed the “broken-wing display.” One researcher commented that adult females have a good sense of how exposed the young are to the elements and that determines how quickly they come back to the young – returning more quickly on very hot days for instance (M. Allen pers. comm.). After our visit, I decided to stay away for a while. However, during a July 15 visit by Simon Lane, the female immediately flushed away from the young (even though he was 50 ft away!) and performed the broken-wing display and then a threat display (S. Lane pers. comm.). When Simon observed and photographed the chicks on July 18, they had grown considerably, since July 12 (S. Lane pers. comm.). By July 23, both “chicks” were smaller free-flying versions of the adult female and could be distinguished not only by size but their barred throats – unlike the clean throat patches of the adults. Since the first flight is usually during the 17th or 18th day of life (Dexter 1952), my assumption that the chicks were about five days old when first photographed is probably accurate. Furthermore, since the incubation period ranges from 16-20 days (Dexter 1977, Campbell et al. 1999), the eggs were probably laid somewhere in the range of June 18-22. This is several weeks later than a nest discovery with two eggs at Lakehurst on June 4, 2000 (T. Boyle pers. comm.). Tom’s birds were said to be close to fledging on July 13, 2000 (T. Boyle pers. comm.). The Lakehurst nighthawks chose an area of open sand surrounded by dwarf scrub oaks and scattered grasses, on the outskirts of the “parachute drop zone” (T. Boyle pers. comm.). Back to Bayonne, on July 28, I observed the two young birds roosting by the female (last time I observed the female). My last sighting of the two chicks was on August 6. (Note: The adult male was never observed roosting with the family group.)
Additional areas with summering nighthawks
Armstrong, R. H. 1995. Guide to the birds of Alaska. 4th ed. Alaska Northwest Books, Seattle, WA.
Brigham, R. M., Janet Ng, R. G. Poulin and S. D. Grindal. 2011. Common Nighthawk (Chordeiles minor), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/213doi:10.2173/bna.213
Campbell, R. W., N. K. Dawe, I. McTaggart-Cowan, J. M. Cooper, G. W. Kaiser, and M. C. E. McNall. 1990. The birds of British Columbia. Vol. 2. R. Br. Columbia Mus. Victoria.
Dexter, R. W. 1952. Banding and nesting studies of the Eastern Nighthawk. Bird-Banding 23:109-114.
Dexter, R. W. 1977. Further notes on banding and nesting studies of the Common Nighthawk in northeastern Ohio. Inland Bird Banding News 49:43-49.
Fowle, C. D. 1946. Notes on the development of the nighthawk. Auk 63:159-162.
Godfrey, W. E. 1986. The birds of Canada. Rev. ed. Natl. Mus. Canada, Ottawa.
Hilty, S. L. and W. L. Brown. 1986. A guide to the birds of Colombia. Princeton Univ. Press, Princeton, NJ.
Marzilli, V. 1989. Up on the roof. Maine Fish and Wildlife 31:25-29.
Meyer De Schauensee, R. M. 1970. A guide to the birds of South America. Livingston Publ. Co. Wynnewood, PA.
Rust, H. J. 1947. Migration and nesting of nighthawks in northern Idaho. Condor 49:177-188.
Sutton, G. M. and H. H. Spencer. 1949. Observations at a nighthawk’s nest. Bird-Banding 20:141-149.
Walsh, J., Elia, V., Kane, R., and Halliwell, T. 1999. Birds of New Jersey. New Jersey Audubon Society, Bernardsville, NJ.