By Paul Castelli, Research Scientist II, Bureau of Wildlife Management
By Paul Castelli, Research Scientist II, Bureau of Wildlife Management
Long-term surveys of bobwhite numbers in New Jersey document what farmers and other landowners already knew: bobwhite numbers have steadily declined for over 40 years and they have disappeared in many areas of the state. The U.S. Geological Survey’s North American Breeding Bird Survey showed that during the late 1960s, the average number of bobwhite heard calling in New Jersey south of Route 33 was approximately 35 per survey route, yet has averaged less than one bird per route during recent years (Figure 1). Radio telemetry studies of bobwhite recently conducted in conjunction with the University of Delaware found that bobwhite reproduction is adequate, with 14.2 eggs per nest and an estimated 45 percent hatch rate for nests (Collins et al. 2009). However, the estimated annual adult mortality rate of the radioed bobwhite was an astonishing 94.7 percent, much too high for the population to sustain. Avian predators dominated mortality causes; however, house cat mortalities were noteworthy. Mortality due to hunting was low (Lohr et al. 2010). The already high rate of adult mortality was even higher during the winter of 2009–2010 due to record snowfall.
Biologists know that bobwhite population models identify winter mortality as a critical portion of annual survival (Sandercock et al. 2008). Reducing hunting mortality is one step biologists can take to lower mortality relatively quickly. Habitat loss and fragmentation are known to be the ultimate causes of the bobwhite’s decline, making the restoration of suitable habitat the primary means by which we can recover the bobwhite population. To address all these issues, New Jersey Division of Fish and Wildlife has prepared a plan for the recovery of New Jersey’s bobwhite population. The full plan can be found on Fish and Wildlife’s Web site. The Action Plan is summarized below.
New Jersey Northern Bobwhite Action Plan
Goals and Actions
The Hunt Plan
A New Jersey Northern Bobwhite Hunt Plan was produced as part of Goal VI of the Action Plan. The hunt plan goal is to provide sport hunting opportunity for bobwhite consistent with action plan goals and appropriate for the bird’s annual population level.
Guidelines used to develop the hunt plan include maintaining desired population levels, maximizing hunting opportunity, as appropriate, keeping regulations simple and learning how harvest regulations affect the population. Bobwhite harvest regulation packages that give consideration for recovery from low population levels and for taking advantage of additional harvest opportunity at high populations are proposed.
The average number of bobwhite heard on the Breeding Bird Survey routes will be used to determine the appropriate harvest regulation. At present, the 0.6 bobwhite per route heard during last year’s survey demonstrates that New Jersey’s population of this game bird is too low to support a hunting season. Therefore, the next Game Code proposes to close the hunting season for wild bobwhite beginning in the fall of 2011. Once the three-year average Breeding Bird Survey count exceeds 2.5 bobwhite per route, a limited hunting season will resume.
Over a century of bobwhite stocking failed to increase wild bobwhite populations or re-establish wild populations. This is not unexpected as habitats have a certain carrying capacity and therefore can only sustain a finite number of birds. Additionally, pen-raised bobwhite are generally unsuited for survival in the wild (Roseberry et al. 1987, Perez et al. 2002). Releasing pen-raised bobwhite for put-and-take hunting has several potential negative consequences.
Pen-raised bobwhite released into the habitats of wild bobwhite could result in increased mortality of native bobwhite from both harvest and predation. Usually, hunter numbers, effort and harvest decline as bobwhite abundance declines. Stocking eliminates this phenomenon as hunters can always expect to encounter bobwhite, leading to sustained hunting pressure on wild bobwhite residing in stocked areas. Researchers found that wild bobwhite were attracted to the calling of recently released pen-raised bobwhite and within one hour were usually found within 50 yards of the released birds (DeVos and Speake 1995). Eggert et al. (2006) found that stocking pen-raised bobwhite affected behavior, lowered survival and increased the hunter susceptibility of wild birds. Hunters have no way to ensure that only stocked birds are harvested. In addition, artificially high numbers of bobwhite may attract non-human predators thus leading to higher predation of wild birds.
Pen-raised bobwhite that breed with wild birds may lower the genetic quality of the population (DeVos and Speake 1995). Evans et al. (2006) found that genetic quality was reduced in wild x pen-raised bobwhite crosses. Released bobwhite that survive until (or are released during) the breeding season compromise efforts to measure population indices for wild populations. Released bobwhite are also a potential avenue for disease transmission to wild birds (Landers et al. 1991).
Figure 1. Average number of bobwhite heard in New Jersey statewide during USGS North American Breeding Bird Surveys, 1966–2008.
The New Jersey Northern Bobwhite Action Plan calls for stocking to be restricted in order to protect wild bobwhite populations from the negative effects of stocking. The hunting season length and bag limit for all stocked, pen-raised bobwhite will be the same as for wild bobwhite, except for semi-wild and commercial preserves that were properly licensed prior to or during the 2009-2010 season. Stocking of pen-raised bobwhite on Fish and Wildlife’s wildlife management areas (WMAs) within the wild bobwhite zone will be restricted to Greenwood and Peaslee WMAs and supplemented with chukar partridge and/or pheasant stocking. Private bobwhite stocking is strongly discouraged. Stocking of pen-raised bobwhite will not be permitted from May 2 through August 31. Hunters on semi-wild and commercial shooting preserve lands will be encouraged to stock ring-necked pheasants or chukar partridge in place of pen-raised bobwhite.
Citations for the complete plan:
Collins, B. M., C. K.Williams, and P. M. Castelli. 2009. Reproduction and microhabitat selection in a sharply declining northern bobwhite population. The Wilson Journal of Ornithology 121(4):688–695.
DeVos, Jr., T. and D.W. Speake. 1995. Effects of releasing pen-raised northern bobwhite on survival rates of wild populations of northern bobwhite. Wildlife Society Bulletin 23(2):267-273.
Evans, K.O., M.D. Smith, L.W. Burger, Jr., R.J. Chambers, A.E. Houston, and R. Carlisle. 2006. Release of pen-reared bobwhites: potential consequences to the genetic integrity of resident wild populations. Pages 121-133 in Gamebird 2006. S.B. Cederbaum, B.C. Faircloth, T.M. Terhune, J.J. Thompson, and J.P. Carroll, eds. 2009. University of Georgia. Athens, GA. 541p.
Eggert, D.A., B.S. Mueller, L. Robinette and S.D. Wellendorf. 2006. Comparison of survival, productivity, movements and habitat use of pre-season released quail on wild northern bobwhites on Groton Plantation, South Carolina. Pages 396-408 in Gamebird 2006. S.B. Cederbaum, B.C. Faircloth, T.M.Terhune, J.J. Thompson and J.P. Carroll, eds. 2009. University of Georgia. Athens, GA. 541p.
Landers, J.L, L.P. Simoneaux, and D.C. Sisson, eds. 1991. The effects of released, pen-raised bobwhites on wild bird populations: Workshop Proceedings. Tall Timbers, Inc. Tallahassee, FL. 36p.
Lohr, M., Collins, B.M., Williams, C. K., and P. M. Castelli. 2010. Life on the Edge: Northern Bobwhite Ecology at the Northern Periphery of Their Range. Journal of Wildlife Management In press.
Perez, R.E., D.E. Wilson, and K.D. Gruen. 2002. Survival and flight characteristics of captive-reared and wild northern bobwhite in southern Texas. Northern Bobwhite Quail Symposium Proceedings 5:81-85.
Roseberry, J.L., D.L. Ellsworth, and K.A. Blake. 1987. Comparative post-release behavior and survival of wild, semi-wild, and game farm bobwhite. Wildlife Society Bulletin 15:449-455.