Atlantic coast joint venture waterfowl implementation plan
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5.2 Contaminants Environmental contaminants continue to be a major problem in wildlife conservation throughout the U.S. including the ACJV. Waterfowl face numerous sources of contamination including municipal waste water treatment facilities, atmospheric deposition from Midwestern power generating facilities, agricultural runoff, industrial production facilities, and coastal oil spills. Waterfowl in the ACJV must contend with numerous toxic compounds that include DDE, PCBs, mercury, lead, and a plethora of pesticides and herbicides. Not withstanding the immediate mortality, contaminants also have been shown to depress an individual’s survival rate and may lower their reproductive rate (Schmitt 1998). Additionally, certain contaminants have been shown to cause birth defects that can lead to lower recruitment rates or reduce future cohorts’ reproductive rates. Elevated levels of heavy metals such as selenium, mercury, and cadmium can impair reproductive function and individual fitness of waterfowl (e.g. Benson et al. 1976, Zicus et al. 1988). Similarly, the negative impacts to reproductive processes of various organochlorines such as DDT and PCB’s are well known (e.g. Babcock and Flickinger 1977). Research conducted in the Long Island Sound in the early 1990’s indicated that exposure to organochlorines and heavy metals may pose serious risks to wintering waterfowl, particularly greater scaup and other diving ducks (Perkins and Barclay 1997). High levels of PCB’s have been found in dabbling ducks in various locations of the ACJV (e.g. Housatonic River) 5.3 Disease Waterfowl in the wild are susceptible to numerous pathogens that result in an unknown number of mortalities every year, but may result in large die-offs under certain conditions (Bellrose 1976, Friend 1988). Waterfowl in the ACJV are susceptible to pathogens that cause avian botulism (Clostridium botulinum), avian cholera (Pasteurella multocida) and duck plague (also known as duck virus enteritis; herpes virus). It is believed that mortality from disease has increased substantially over the last couple of decades (Friend 1988) Also, as waterfowl become more concentrated as a result of habitat loss and degradation, local populations become more susceptible to major die-offs these pathogens can cause. Initiation of monitoring programs where waterfowl tend to concentrate during migration and the winter can be useful in allowing early detection of epidemic outbreaks of these diseases. 5.4 Invasive Species The proliferation of numerous exotic species of vegetation poses a serious risk to waterfowl throughout the ACJV. Perhaps, this is most evident in Florida where the impact of non-indigenous (non-native, alien, or exotic) plants is one of the greatest threats to Florida's natural areas. In 1978, over 170 non-native plants species were naturalized (reproducing and continuing to exist without cultivation) in Florida’s most heavily popularized counties (St. Lucie, Martin, Palm Beach, Broward, and Dade, Austin 1978). Statewide, 1,200 or 29% of the plant species now growing outside of cultivation in Florida are non-native (Wunderlin et.al. 1996). These species tend to expand rapidly and have widespread, detrimental ecological impacts. Examples include, Australian Pine (Casuarina spp.), which have devastated beach plant communities, Brazilian pepper (Shinus terebinthifolius), which now infests over 405,000 ha in the state, melaleuca (Melaleuca quinquenervia), which now forms monocultures in nearly 162,000 ha of wetlands, and hydrilla (Hydrilla verticillata), which has displaced native aquatic plant communities in over 50% of Florida’s water bodies. Other invasive species include Japanese climbing fern (Lygodium japonicum), para grass (Urochloa mutica), waterhyacinth (Eichhornia crassipies), and water lettuce (Pistia stratiotes), among others (Langeland and Burks 1998). However, Florida is not the only state in the ACJV to experience significant ecological degradation due to invasive species. Control of invasive species is an ongoing effort from Maine to Florida. The most problematic invasive species that negatively impact waterfowl resources in the ACJV include: alligatorweed, purple loosestrife, common reed and water chestnut. 5.4.1 Alligatorweed Alligatorweed (Alternanthera philoxeroides [Mart.] Griseb.) is a South American immigrant that has invaded waterways in the United States, primarily in the southeastern states. It also is a weed in tropical and mild temperate regions around the world. Alligatorweed roots readily along waterways and then grows over the water surface as an anchored floating plant. It also grows terrestrially during dry periods. Alligatorweed is a federal noxious weed and a prohibited or noxious plant in Arizona, California, Florida, and South Carolina (USDA, NRCS, 1999). Alligatorweed grows in the coastal plain from Virginia to southern Florida and westward along coastal areas to Texas. A distribution map provided by Reed (1970) indicates that the northern limit inland is at about the middle of Alabama, Georgia, and South Carolina, with an extension slightly further north in the warmer Mississippi Valley. Current data on the extent of infestation and overall control costs in the Southeast are lacking. Alligatorweed, like many other invasive aquatic plants, displaces native plants in ditches, along banks, and in shallow water (Holm et al., 1997). Alligatorweed disrupts water flow causing increased sedimentation, and it shades submersed plants and animals causing reduced oxygen levels beneath the mat (Quimby and Kay, 1976). A variety of biological and chemical control approaches have been tried. The biological control methods are more successful in the southern-most range of alligatorweed as opposed to the northern range extend of alligatorweed. Current costs are approximately $170 to $370/ha for control of alligatorweed with the herbicides glyphosate and fluoridone. 5.4.2 Purple Loosestrife The invasive plant, purple loosestrife (Lythrum salicaria), has been a serious detriment to wetland ecosystems for the past several decades. Its ability to suppress native plant communities has resulted in the eventual alteration of a wetland’s structure and function (Thompson et al. 1987). Purple loosestrife has little value for resident wildlife in these communities, resulting in a reduction in numbers and species richness. In areas where loosestrife seeds are present in the soil, any disturbance quickly results in a monoculture which excludes native plants. This has made it very difficult to employ management techniques such as periodic drawdowns or even the construction of dikes to create shallow impoundments. Attempts to suppress purple loosestrife have included mowing, burning, application of herbicides, disking and flooding, with only temporary relief. Recently, biological control of purple loosestrife has had significant results. Testing begun in the late 1980s indicated a high degree of host specificity by the weevil, Hylobius transversovittatus, and two beetles of the Genus Galerucella. Field studies at several State Wildlife Management Areas and two National Wildlife Refuges in New York resulted in noticeable effects on the vigor of these plants about 3 years post-treatment. After 5 years, the plants were suppressed in extent by 80 to 90 % of pre-treatment levels (DEC files). It is now believed that these agents are capable of controlling purple loosestrife at tolerable levels on our landscape. These insects are currently being distributed and released in over 30 states and in Canada. 5.4.3 Common Reed Common reed (Phragmites australis) is an invasive perennial grass that is propagated through the rhizomes. Although the species is now thought to be native to North America, a more invasive genotype appears to have been introduced from the Old World. Due to its broad salinity tolerance, Phragmites typically creates large monocultures in both brackish and freshwater wetlands. Homogenous stands of Phragmites significantly degrade ecological function of tidal wetlands (Marks et al. 1994) and drastically reduce plant species diversity (Warren 1994). Loss of diversity in Phragmites dominated wetlands is not limited to plant species. Numerous studies (e.g. Benoit and Askins 1999, Angradi et al. 2001) have documented the loss of both avian and macro-invertebrate density and taxa richness in Phragmites-dominated marshes. In areas where changes in tidal hydrology (e.g. tidal restrictions caused by roads) have resulted in a decrease in salinity and or water levels, it may be possible to control Phragmites by restoring the original tidal hydrology. Other control methods include cutting, burning and application of herbicides but these methods often control Phragmites only for short periods. Initial investigations of biological control have produced promising results and should be supported. (Bernd Blossey, personal communication). 5.4.4 Water Chestnut Water Chestnut (Trapa natans) is a floating-leaved aquatic native to Europe, Asia and tropical Africa. Introduced to New York State in the late 1800’s, it has spread via interconnected waterways into Vermont and Massachusetts. It has also been confirmed in Connecticut, Maryland and Virginia. A fierce competitor in shallow bays with soft bottoms, water chestnut creates nearly impenetrable mats across wide areas of water, out competing native submergent and floating-leaved aquatics, and is of limited value to waterfowl and other wildlife. Chemical control and manual and mechanical harvesting techniques are being used to control populations (Naylor 2003). 5.5 Predation and Harvest Although several species (e.g., American Black Duck, Canvasback and Wood Duck) are thought to be susceptible to the effects of additive hunting mortality there is no credible evidence that current hunting regulations in the conterminous U.S. are too liberal. An exception to this is Puerto Rico, where hunting is thought to be a major threat to the West Indian Whistling-Duck in Puerto Rico (Puerto Rico DNR, unpubl. report). Unlike harvest mortality, nest predation is related to habitat quality and is affecting local populations of nesting waterfowl in different regions of the JV. Specifically, the USDA’s Animal and Plant Health Inspection Service are conducting a predator control program on Virginia’s barrier islands. One goal of this program is increasing black duck reproduction which had dropped due to nest predation by raccoons and red fox (U.S. Dept. of Agriculture 2005). In Puerto Rico, predation of chicks has been noted as a major threat to White-cheeked Pintails (Puerto Rico DNR, unpubl. report). 5.6 Human population and disturbance As of 2000, the ACJV was home to almost 38% of the U.S. population excluding Alaska and Hawaii (U.S. Census Bureau, Table 5.1). While the percentage of the total U.S. population within the JV boundary has decreased from 41% to 38% since 1950, the absolute number of people living in the JV has increased by more than 46 million people. Such an increase is accompanied by an increase in the infrastructure required by our society: more housing, new roads, and new buildings for businesses and shopping. Within the ACJV this is the largest single factor resulting in the fragmentation and loss of habitat. The increase in development and urbanization is not distributed randomly across the JV (Fig. 5.1), however. The majority of the increase is concentrated along the Atlantic seaboard which contains some of the best waterfowl habitat within the JV. As a consequence of the increasing human population, waterfowl have been and will continue to be subjected to increasing human disturbance. Conflicts over recreational use of areas protected to provide habitat for waterfowl and other wildlife will become more frequent, reducing refuge areas and pushing waterfowl to less favorable sites. Such disturbances could lead to greater energetic demands during the winter when it is normally difficult to find adequate food resources. Such a scenario would mean that individuals enter the breeding season with fewer fat reserves which could lead to lowered reproductive rates. Also, increasing storm water Table 5.1. Census estimates of total U.S. population living with the ACJV from each Decennial census conducted by the U.S. Census Bureau.
1 – Percent of conterminous US population estimate plus the Commonwealth of Puerto Rico 
Figure 5.1. Percent change in population by county between decennial censuses of 1950 - 1970 and 1970 - 2000. Data from U.S. Census Bureau. runoff, with increased siltation and chemicals associated with urbanization degrade water quality and reduce habitat. 5.7 Global Climate Change Although there is a great deal of uncertainty in the exact magnitude of predicted changes, most global climate change models suggest that global temperatures will continue to rise at unnaturally fast rates, sea levels will rise as a result of melting ice fields and precipitation patterns will change. Inkley et al. (2004) state “Ignoring climate change is likely to increasingly result in failure to reach wildlife management objectives.” Thus, it is important that the potential impacts of climate be understood so that appropriate management plans can be drafted. Within the ACJV, it is generally believed that the Southeast and the Mid-Atlantic States will experience the greatest change (Smith 2004 – Pew Center for Climate Change). Both of these regions will be extremely susceptible to rise in sea levels from a combination of sea level rise and marsh subsidence putting some of the ACJVs most important coastal marshes at risk of being lost (Inkley et al. 2004, Smith 2004). In the Chesapeake Bay, sea level rise may be as much as 19cm by 2030 and 66cm by the end of the century (Inkley 2004). Such dramatic increases in water level will result in the loss of suitable foraging habitat for wintering waterfowl. In the Southeast, increasing temperatures may reduce water quality and increase the likelihood of severe hurricanes (Smith 2004). The Great Lakes/ St. Lawrence is expected to receive less runoff under most existing climate change models that will result in lower water levels in the region. Although this area is important for waterfowl throughout the year, such impacts may have a disproportional effect on the species that use this area as major staging grounds during migration (e.g., Greater Snow Goose). In addition to the impacts already mentioned, it is expected there will be a general northward migration of ecosystem types as a result of increasing temperatures (U.S. Department of State 2002, Smith 2004). Prasad et al. (USFS 1999) have produced predictive models showing how forest types respond under five different climate change models as the result of doubling CO2 concentrations. There is good agreement among the predictions based on the five different models. Generally, oak/hickory and oak/pine forests become the dominant forest types throughout the ACJV, with the complete loss of sub-boreal forest types. Whether this will have an impact on waterfowl is unknown, but is mentioned to illustrate the severity of the changes facing wildlife managers. 6. GOALS AND OBJECTIVES FOR WATERFOWL CONSERVATION 6.1 Continental Prioritization The 2004 NAWMP Update set continental population objectives and regional priorities for waterfowl conservation in North America. The ACJV is responsible for taking those objectives and priorities and translating them to objectives and priorities for the joint venture. Population objectives have only been set for nine species or populations of ducks, five species or populations of geese and one species of swan (Table 6.1). Of the 15 species or populations of waterfowl that occur in the ACJV and have continental population objectives, only four (Northern Pintail, American Black Duck, American Wigeon and the Southern James Bay population of Canada Geese) are below their stated goals. Continental prioritization for ducks considered only two factors, continental population trend and combined continental harvest. Population trends were estimated from the Waterfowl Breeding Population and Habitat Survey for the period 1970 – 2002 and were categorized as: increasing, stable, unknown or decreasing. The latter two categories were weighted equally in the prioritization scheme. Data from the U.S. FWS Waterfowl Parts Survey and similar data from Canada were combined to provide an estimate of total harvest. Species were categorized according to their composition of the total harvest as follows: high (>15%), moderate (1-14%) and low (<1%). Continental prioritization for geese and swans deviated in that harvest was not considered and was replaced by deviation from the stated population objective. This deviation was categorized as: below, unknown, at objective or above. Final priority categories were assigned based on a matrix of these factors: for ducks (Table 6.2), for geese and swans (Table 6.3). For waterfowl species occurring in the ACJV, the assigned continental priority values are shown in Table 6.4. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||