Hi all, Not to belabor these points, but I posed the specific question to Mike Burger of Audubon NY and he spoke with Bryan Swift, NY DEC's top waterfowl management guy -- below is Mike's response. A bit technical, but very informative.
KEN Ken Rosenberg Conservation Science Program Cornell Lab of Ornithology 607-254-2412 607-342-4594 (cell) k...@cornell.edu<mailto:k...@cornell.edu> Begin forwarded message: From: Mike Burger <mbur...@cornell.edu<mailto:mbur...@cornell.edu>> Date: January 7, 2013 12:48:10 PM EST To: Kenneth Victor Rosenberg <k...@cornell.edu<mailto:k...@cornell.edu>> Subject: RE: (Long comment) Exempt part of Cayuga Lake from hunting diving ducks Ken, I don’t have time to get into this issue in a thorough way, but I’ll share my initial reactions on the question of whether or not this is a conservation issue. It would be difficult to make the case for a biological need to ban duck hunting from any portion of Cayuga Lake. The evidence suggests this is not a conservation issue. Waterfowl management is far more complex than John Confer’s message below suggests. In fact, it’s wrong to assert that hunting regulates duck populations. From what I have heard from Bryan Swift, DEC’s rep on the flyway council technical section, which sets the waterfowl seasons, hunting is sometimes an additive mortality factor and sometimes not. For species whose populations we want to increase (per the North American Waterfowl Management Plan), the objective in setting hunting seasons and bag limits is generally to keep the mortality from hunting below the level at which it becomes additive. (It has been difficult to increase mortality from hunting of Snow Geese up to the point where it is additive.) The availability of wetland breeding habitat (primarily in the prairie pothole region for many species) is a hugely important factor in the demographic models used to set hunting seasons. Reproduction is highly influenced by the number and size of wetlands, which is driven primarily by precipitation and farming practices (which are addressed by Farm Bill programs). In general, breeding habitat is the limiting factor; only so many ducks will get to reproduce. Keeping hunting mortality in the compensatory range helps keep the populations such that they can make use of any available habitat. Banding studies indicate that overall hunter harvest rates on diving ducks are very low, probably on the order of 5-10%, and not likely to be adversely affecting any populations. The USFWS does spend a lot of money flying breeding (to survey wetlands as well as ducks) and wintering areas, surveying hunters, banding ducks, etc. to feed their models, but even so, there are limits to what can be concluded about impacts of weather, predation, hunting, and other factors, especially at the local level. Ducks are managed at the flyway and continental level, and hunting seasons and bag limits are coordinated among countries and states. Determining impacts of local hunting activities on continental populations would be difficult, and it’s probably not necessary as long as big-picture populations are faring well. It would be even more difficult to determine impacts of local hunting on local wintering populations because the birds are so mobile and may shift wintering areas from one year to the next depending on weather conditions and other factors. The “hunting season” variables that are manipulated are the number of days when hunting is allowed, when those days occur on the calendar, and how many of each species are allowed to be taken each day and possessed at any one time, but these variables have multiple and interacting effects on the populations. Related to these variables are several impacts other than direct, legal take, including crippling, poaching, and even disturbance - and all of these impacts essentially are factored into the models. That is, the length and timing of hunting seasons brings into the models the related effects of non-lethal impacts such as disturbance, and those are taken into consideration when setting the seasons. If I follow the biological component of the argument that has been presented, it is that large proportions of diving duck populations use the Finger Lakes in the winter and disturbing those birds from their preferred habitat during the hunting season must be detrimental to their survival and therefore to their populations. But, because the length and timing of the hunting season is selected on the basis that the models indicate the overall impact will not result in additive mortality for the populations, and the populations continue to increase (e.g., Redheads), that seems to suggest that the argument is wrong. I fully understand that this issue has complex societal aspects as well and personally I support those who are calling for tolerance and accommodation, but I thought it would be helpful to address the biological aspects in more depth. Mike From: John Confer [mailto:con...@ithaca.edu] Sent: Thursday, January 03, 2013 2:55 PM To: CAYUGABIRDS-L; Confer, Karen; John W. Fitzpatrick Subject: (Long comment) Exempt part of Cayuga Lake from hunting diving ducks Hi Folks, CBC are always fun for many reasons. It tickles the grey cells to think about population trends and regulatory factors. I shared a fun discussion about the impact of hunting on waterfowl on the south end and the rest of Cayuga Lake and we discussed if there were objective data on population abundance to justify preventing such hunting. This got me thinking. The Fish and Wildlife spends an immense amount of effort to census waterfowl every year: extensive aerial surveys that criss-cross the prairie potholes and elsewhere and Hudson Bay coast, really extensive banding efforts, and hundreds of hours of ground surveys, etc. All of this provides an estimate of pop abundance for each species. This is used to set bag limits. This immense effort is predicated on the belief that hunters are one of the significant factors that regulate waterfowl abundance, and that to sustain the population at nearly level numbers over the long term, one must adjust the bag limit in some proportion to the abundance at the start of fall migration. In the same line of reasoning, the spring snow goose hunting season and the split canada goose hunting season are all based on the belief that hunting in general regulates waterfowl abundance. The newly proposed expansion of waterfowl hunting on snow geese for Montezuma is also based on hunting will continue to regulate abundance. Either, hunting does regulate waterfowl abundance, or the F&WS is fooling us and themselves. It is impossible to acquire the specific, statistically-based evidence that hunting regulates the specific population of waterfowl using Cayuga Lake for several reasons. There is no reason to believe that the impact of hunting of waterfowl on Cayuga Lake is exempt from this generality. In fact, it would be incumbent for the merit of such an argument to provide evidence why Cayuga Lake is an exception to the general concept of waterfowl management. Difficulties in making data-based arguments about waterfowl on Cayuga Lake include many factors. 1) There is no estimate of the take, which obviously means you can't quantify the impact. The absence of the fundamental data limits the ability to say if there is or isn't an effect. 2)There is no way to estimate the impact of driving the waterfowl out of their favored foraging site. A reasonable hypothesis is that winter food supply is important. Waterfowl speak with their wings. This provides strong support for the hypothesis that the shallows of Cayuga Lake provide a favorable foraging site. There are no other areas in the inland northeast that have as many diving ducks in mid-winter as Seneca and Cayuga Lakes. The abundance of diving waterfowl on these lakes during times outside of the hunting season suggest that this food source may be one of the best in the entire winter range. In which case, limiting access to a food source for part of the winter may be very deleterious, and could have negative effects on far more than the number killed by shot. 3) When I first came here, there was a waterfowl bander on Seneca Lake. I never met him and don't recall his name. I was told, with what seemed like high credibility, that banding indicated that waterfowl moved back and forth between Seneca Lake, and by inference Cayuga Lake as well, and the coast repeatedly during the winter. Thus, populations on Seneca Lake, and by inference Cayuga Lake, are a sub-sample of the eastern population. The suggestion that an increase in waterfowl on Cayuga Lake during the winter shows that hunting on Cayuga Lake has no impact on the Cayuga Lake population fails to consider that the Cayuga Lake population is a portion of and exchanges with the east coast wintering population. In order to detect an effect of Cayuga Lake take, it would have to be large enough to impact a perceptible portion of the entire eastern wintering population. 4) Reliable data on the impact of hunting on diving ducks on part of Cayuga Lake can not be based on data documenting an effect of hunting, because there is no such data. Further, it would be nigh impossible to obtain. Such data would require a series of years with and without hunting seasons, including years when the continental populations are high and are low. It would require a level of precision on the take of the population and quantitative information on the exchange with the larger coastal population. It does not seem feasible to me to obtain such a data-based decision on the impact that hunting on Cayuga Lake has on the east coast population of diving ducks. I believe such a ban can be defended on general arguments. The decision to create federal wildlife refuges is based on the argument that waterfowl need some place to forage and loaf where they are free of hunting pressure. J. "Ding" Darling, with Ithaca relations, helped popularize this perception. The refuge system was proposed as a means to sustain a high population for hunters for the long run. For diving ducks, Cayuga Lake has no refuge because during the hunting season ponds are frozen and the ducks are chased up and down the entire shore, the only available habitat. While some shorelines do not allow hunting access, hunting and fishing from boats eliminates these sites as loafing areas. The great majority of the diving ducks who would use this lake if they were not hunted, are either killed or driven out during the hunting season. (Dabblers, who in the largest part migrate south of here when the shallow waters freeze, are affected by a different mixture of factors.) It is compatible with the basic reason for the refuge system to presume, until shown otherwise, that the loss of a highly favorable foraging and loafing site is highly likely to have a negative impact on the population. In the long run, this is deleterious to hunters. An entirely different argument is based on the relative involvement for non-consumptive watching and hunting. Hunting diving ducks on Cayuga Lake is obviously deleterious to birders and there are far more birders than hunters. In New York, 3,800,000 people participated in wildlife watching in 2006 and spent $1.5 billion, while 568,000 people participated in hunting for waterfowl and upland game in NY spending $715 million. More locally, at MNWR the current annual use is approximately 124,924 visitor-days by those who participated in wildlife watching, photography and environmental education and 2252 visitor-days for individuals who hunt for upland game and waterfowl. I support hunting: the deer population should be greatly reduced and hunting seems to be the optimum method, and, e.g., canada geese and snow geese should be greatly reduced. Shooting diving ducks on all parts of Cayuga Lake is not in the same category to me. First, I don't think that a few individuals should greatly reduce the pleasure of many. Second, the initial popular movement and reasoning for the creation of the refuge system were predicated on the hypothesis that preserving favorable sites for foraging and for loafing are essential to maintaining future populations that are abundant enough to allow hunting success. I believe that argument is valid and support its philosophy. Some portions of the Cayuga Lake shoreline, which are attractive to diving ducks, should be exempt from hunting. Cheers, John Confer -- Cayugabirds-L List Info: http://www.NortheastBirding.com/CayugabirdsWELCOME http://www.NortheastBirding.com/CayugabirdsRULES http://www.NortheastBirding.com/CayugabirdsSubscribeConfigurationLeave.htm ARCHIVES: 1) http://www.mail-archive.com/cayugabirds-l@cornell.edu/maillist.html 2) http://www.surfbirds.com/birdingmail/Group/Cayugabirds 3) http://birdingonthe.net/mailinglists/CAYU.html Please submit your observations to eBird: http://ebird.org/content/ebird/ --
