WILDLIFE SCIENCE: LINKING ECOLOGICAL THEORY AND MANAGEMENT APPLICATIONS - CHAPTER 5 docx

NEED AND BASIS FOR WETLAND MANAGEMENT Acquisition, easement, or legal designations cannot adequately protect wetlands, because they are especially subject to rapid changes in structure a

5 An Ecological Basis for

Management of Wetland

Birds

Guy A Baldassarre

CONTENTS

Need and Basis for Wetland Management 80

Landscape Ecology and Wetland Management 82

Wetland Plant Succession 84

The Role of Models 86

Taxonomy and Phylogenetic Systematics 88

An Upshot 90

Acknowledgments 90

References 91

Wetland birds are species dependent on fresh, salt, or brackish-water wetlands to satisfy most, if not all, life history requirements They are a subset of the larger waterbirds group, which comprises about

800 species dependent on any aquatic habitat, but not necessarily wetlands (Reid 1993) Hence, the wetland birds group excludes all seabirds (e.g., albatrosses, auks, and boobies) and most coastal waterbirds (e.g., gulls, terns, pelicans, and cormorants), but the group is nonetheless still large, diverse, and widely distributed

Globally, the wetland birds group comprises about 620 species, of which 197 (31.8%) occur

followed by the rails, gallinules, and coots (Rallidae — 134 species) Other significant groups are the sandpipers (Scolopacidae — 87 species), plovers (Charadriidae — 66 species), egrets, herons, and bitterns (Ardeidae — 63 species), ibises and spoonbills (Threskiornithidae — 33 species), grebes (Podicipedidae — 19 species), storks (Ciconiidae — 19 species), and cranes (Gruidae — 15 species) Several smaller families of wetland birds contain 1–10 species

Unfortunately for wetland birds, wetland habitats of all types have undergone massive loss and alteration In the United States, for example, the “best estimate” is that 89.5 million ha of wetlands existed in the lower 48 states at the time of colonial America, with another 69 million ha in Alaska and 24,000 ha in Hawaii By the mid-1980s, however, only about 42 million ha remained in the lower 48 states, which represented a loss of 53% (Dahl 1990) Some 22 states have lost 50% or more

of their original wetlands; 11 have lost more than 70% By 1997, 42.7 million ha remained in the lower 48 states, of which 95% were inland freshwater wetlands (Dahl 2000)

Globally, wetland loss may approach 50% (Dugan 1993), although loss is more severe in some regions than others Based on a summary appearing in Mitsch and Gosselink (2000, 38), losses exceed 90% in Europe and New Zealand, 60% in China, and more than 50% in Australia Within nations, certain regions or types of wetlands may be particularly affected For example, about 67%

79

TABLE 5.1

Global and North American Diversity of Wetland Birds a

Percentage of North American North American Family Common name Global species a species b species

aData are from Clements, J F 2000 Birds of the World: A Checklist, 5th edn Temecula, CA: Ibis Publishing.

bData are from American Ornithologists’ Union (AOU) 1998 Check list of North American Birds, 7th edn.

Washington, DC: American Ornithologists’ Union.

of all mangrove swamps in the Philippines are gone, as are an estimated 80% of the Pacific coastal estuarine wetlands and 71% of the prairie potholes in Canada (Whigham et al 1993)

This extensive loss of habitat is exacerbated, because wetland destruction has differentially involved the “best” wetlands for wildlife Such wetlands often occur on the most productive soils for agriculture (e.g., prairie and riparian wetlands), wherein those wetlands strongly compete with humans for space Productive coastal wetlands have been differentially targeted for expansion of coastal cities, shipping channels, and agricultural development, especially rice and various forms of aquaculture (e.g., shrimp) Hence, many of the remaining wetlands in the United States and elsewhere often are poor-quality wildlife habitat For example, in an early assessment of wetlands in the United States and their importance as waterfowl habitat, 70% were ranked as low or of negligible value (Shaw and Fredine 1956) Arctic wetlands are the major exception to this general pattern, because soils are poor and growing seasons short; hence, agricultural activities are virtually nonexistent in the Arctic, and arctic wetlands are critical breeding habitat for some waterfowl and shorebirds Nonetheless, the extensive quantitative and qualitative loss of wetlands has severely affected wetland birds of all taxonomic groups Indeed, in comparison to species numbers summarized

in Table 5.1, some 175 (28.2%) are listed by International Union for the Conservation of Nature

(4.8%) are listed extinct, 21 (3.4%) as critically endangered, 37 (6.0%) as endangered, 46 (7.4%) as vulnerable, and 41 (6.6%) as near threatened (Table 5.2) The most affected group is the cranes (66.6% listed), followed by the rails (35.1%), sandpipers (26.4%), waterfowl (26.1%), herons (20.6%), and plovers (19.7%)

NEED AND BASIS FOR WETLAND MANAGEMENT

Acquisition, easement, or legal designations cannot adequately protect wetlands, because they are especially subject to rapid changes in structure and plant composition Hence, active management

TABLE 5.2

Total Number of Species of Wetland Birds Listed in Four Major Categories by the International Union for the Conservation of Nature and Natural Resources (2006)

Family Common name Extinct a endangered Endangered Vulnerable threatened

a Species extinct since 1500.

is usually critical to maintain the functional values that led to protection in the first place! Active management of remaining wetlands is especially essential, because a lesser amount of habitat must now maintain population levels of wetland birds and other wetland wildlife once supported by a wetland base nearly twice as large as that in North America today

Wetlands management basically synchronizes availability of habitat and habitat components (e.g., food) to coincide temporally and spatially with life history events affecting survival and repro-duction of populations of target species or species groups Most wetland birds are migratory, and species-specific migratory patterns, habitat use, and other life history requirements are fairly well known, especially in North America Hence, the spatial and temporal considerations of wetland man-agement (i.e., “where and when”) are well known, and techniques (i.e., “how”) for actual manman-agement

are very well documented (Payne 1992) However, managers must understand why protection and

manipulation of certain habitats benefits some species and species groups but not others, and then reconcile issues of size, juxtaposition, connectivity, and habitat diversity Managers must

under-stand why certain factors are important to issues of biodiversity, because they are now called upon

to address an array of wetland-dependent biota in addition to a focus species or group Finally, managers must understand why a particular management technique is warranted in one situation but not another Wetland managers may wish away this level of understanding in the decision-making process, but such complexity is only accelerating with the new millennium, coincident with perhaps the most urgent need ever to protect and manage wetland habitats and associated biota such as wet-land birds Further, despite increasing attention to wetwet-land conservation issues everywhere, wetwet-land loss will continue wherein management of remaining wetlands will be of paramount concern Thus, increasingly complex issues will characterize the landscape for wetland managers in the future, but

that difficulty is not insurmountable, and certainly not an a priori recipe for failure.

Wetland managers must understand the ecological underpinnings of certain management approaches (i.e., an ecological approach) to understand why they are successful A “how-to” approach dooms managers to a “hit-or-miss” strategy that is often ineffective, unrepeatable, nontransferable among managers, and costly in terms of both time and money The purpose of this chapter is to demonstrate the value of an ecological approach to the management of wetland birds To achieve

that objective, I review the ecological basis for four major approaches to wetland management that

I believe are most effective in the decision-making process associated with wetland bird conservation and management Two approaches focus on habitat considerations (landscape ecology and wetland plant succession), whereas the other two focus on wetland birds themselves (demographic models and phylogenetics)

LANDSCAPE ECOLOGY AND WETLAND

MANAGEMENT

All wetlands occur as individual entities, but wetlands also aggregate into groups or complexes that spatially occur at scales ranging from local to global, the array of which leads management into the realm of landscape ecology Along the path, managers also confront issues such as wetland size and juxtaposition, as well as assessment of species richness and habitat functions Habitat acquisition and legal protection of wetlands are especially concerned with all of the above issues, and landscape ecology has figured prominently in these deliberations even before its formal emergence

in ecology The decision-making tools available to managers have transformed from crude, black-and-white aerial photographs to high-resolution digital satellite images accurate to within a few meters, and the emergence of geographic information systems (GIS) and associated techniques has facilitated detailed quantitative analysis where earlier efforts involved much guesswork Nonetheless, improvement of data quality has not negated application of the principles of landscape ecology to wetland protection efforts

Historically, waterfowl managers were perhaps first to use concepts of landscape ecology in association with acquisition of national wildlife refuges Early managers recognized that nearly all species of waterfowl in North American were highly migratory; hence, management efforts were needed to establish refuges on breeding, wintering, and migration areas, if the annual cycle needs of waterfowl were to be satisfied for the array of species involved For migratory birds in general, these issues were later recognized as “connectivity,” which realizes that individuals move back and forth between specific breeding and nonbreeding areas (Webster et al 2002) Regardless, early wetland acquisition efforts often focused on large tracts of wetlands that formed the basis of many national wildlife refuges Small wetland areas received direct focus from the U.S Fish and Wildlife Service with creation of the Waterfowl Production Areas program in 1959, which recognized the importance

of small wetlands to breeding waterfowl

More detailed relationships about habitat size and species richness of wetland birds stemmed from early studies that spawned the initial theory of “island biogeography,” which established a relationship between the size and isolation of islands and subsequent species richness of birds, spawning the species-area equation now so familiar in conservation biology (MacArthur and Wilson 1967) Subsequent studies examined these issues in an array of insular habitats such as prairies, forests, cemeteries, and, of course, wetlands

The first major study occurred in 1983–84 when Brown and Dinsmore (1986) addressed the influence of size and isolation on the diversity of breeding birds in 30 Iowa wetlands ranging in size from 0.2 to 182.0 ha Data from their study yielded a significant correlation between species richness

richness of wetland birds using active and inactive beaver (Castor canadensis) ponds in south-central

New York

Relative to isolation of habitats, Brown and Dinsmore (1986) found that total area of wetlands

the only significant factor among 12 isolation variables measured Indeed, wetlands in complexes had more species (11) but were half as large (14 ha) as isolated wetlands (30 ha, nine species)

Gibbs et al (1991) found that isolation was weakly correlated (r= 24) with the species richness of birds In a two-variable model, however, wetland size and isolation explained 74% of the variation associated with species richness in Iowa and 43% in Maine

These and other studies certainly provide managers with the guidance that protection of large wetlands and wetland complexes will protect species richness Weller (1981) was perhaps the first to promote the idea that protection of a wetland complex was the best way to protect regional wetland flora and fauna Within such complexes, however, protection of small wetlands may be especially significant in designing programs to protect species diversity For example, Gibbs (1993) modeled the

wetlands ranging in size from 0.05 to 105.3 ha Loss of small wetlands reduced total wetland area by only 19% but decreased the total wetland number by 62%, and increased the inter-wetland distance

by 67% The simulation predicted that local populations of turtles, small birds, and small mammals faced significant risk of extinction with loss of small wetlands This study thereby underscored the value of small wetlands as a means of maintaining species richness of wetland wildlife, including waterbirds Unfortunately, small wetlands are the easiest wetlands to drain or fill Further, because

of their ephemeral nature, small wetlands are often not afforded legal protection and do not garner significant attention from managers Hence, despite their importance, small wetlands are often the first to disappear from wetland complexes

Large wetlands are, of course, critically important within wetland complexes for many reasons, but particularly because their absence affects area-dependent species For example, in their Iowa study, Brown and Dinsmore (1986) found that 10 of the 25 species detected did not occur in wetlands

<5 ha Pied-billed grebes (Podilymbus podiceps) and yellow-headed blackbirds (Xanthocephalus xanthocephalus) are area-dependent species, rarely exploiting habitat outside the vicinity of nesting

areas (Naugle et al 1999)

Managers of waterbirds at a landscape level must also recognize that features other than wetlands

can profoundly influence some species For example, western willets (Catoptrophorus semipalmatus inornatus), breeding in the Great Basin, moved daily from upland nesting sites to wetland foraging sites (Haig et al 2002) Black terns (Chlidonias niger), breeding in South Dakota, were more likely

to occur in landscapes that contained grasslands instead of agricultural fields (Naugle et al 1999) Although many studies have connected issues of species occurrence and richness to landscape-level consideration of wetlands, significantly fewer studies, however, have demonstrated causal relationships Such data largely come from studies of waterfowl, but they are extremely significant, because they can explain why certain patterns occur, which provides a powerful approach to manage-ment decisions Seasonal and temporary wetlands, for example, are heavily used by ducks breeding

in the Prairie Pothole Region of both the United States and Canada, because such wetlands provide habitat for the aquatic macroinvertebrates that provide protein essential for egg production (Krapu 1974; Swanson et al 1979) However, temporary wetlands are substantially less available in drought

years This reduced wetland availability relegates mallards (Anas platyrhynchos) and other dabbling

ducks to foraging in deeper, more permanent wetlands where invertebrates are less abundant Such

a situation then affects mallard fitness, which is reflected in a shorter nesting period and production

of fewer nests During a drought year in North Dakota, for instance, mallards produced dramatically fewer nests than during a wet year, and females remained on study area wetlands for 44 days in the wet year compared with only 16 in the drought year (Krapu et al 1983)

Other studies also have concluded that wetland complexes increase habitat heterogeneity, which

is important to waterfowl and other waterbirds, because life history requirements usually require various types of wetlands (Leitch and Kaminski 1985; Murkin et al 1997) Wetland complexes in North Dakota, for example, contain seasonal, semipermanent, and permanent wetlands that provide optimal brood-rearing habitat for mallards, and subsequent production was greatly enhanced where such complexes were protected by managers (Talent et al 1982) Indeed, mallard broods used up to

11 different wetlands, which again emphasizes the importance of maintaining a complex of wetlands

as a prerequisite for good waterfowl production

Upland landscape variables measured at 10.4 and 41.4 km2best explained nest survival for ducks nesting in North Dakota (Stephens et al 2005) Not surprisingly, nest success was positively related

to the amount of grassland habitat, but success was quadratically related to the amount of grassland edge Stephens et al (2005) speculated that the latter relationship likely occurred because predator communities became most diverse at levels of intermediate fragmentation In contrast, landscapes

with more contiguous grasslands favored endemic predators such as coyotes (Canis latrans) and badgers (Taxidea taxus) over red fox (Vulpes vulpes), raccoons (Procyon lotor), and striped skunk (Mephitis mephitis); the latter three species are significant predators of waterfowl nests Hence, nest

success may be higher where grassland landscapes are more intact, because such sites will favor coyotes and badgers, which have larger home ranges and occur at lower densities than other nest predators such as the raccoon, skunk, and red fox (Sargeant et al 1993) Additionally, coyotes can be especially effective predators on other mammalian nest predators like the red fox For example, Sovada et al (1995) found that duck nest success in North Dakota was merely 2% at a study area

predominately occupied by red foxes compared with 32% in an area where coyotes (C latrans) were

the dominate predator — the two areas were 5 km apart Sovada et al (2000) also reported that daily survival rates of duck nests were significantly greater for nests in large patches of grassland habitat in

Overall, the underpinnings of landscape ecology are demonstrating that the best strategy for waterbird conservation, in terms of both species richness and fitness, is to protect entire wetland complexes, where possible, and to enhance existing complexes by acquiring or restoring those wetlands missing from the complex Furthermore, managers must also recognize that nonwetland habitats such as grasslands and other upland nesting sites are critically important landscape compon-ents that dramatically affect species fitness Protection of the most heterogeneous array of habitats possible, in terms of both size and types, is a clear guiding principle for waterfowl communities, because pairs, broods, and fledged juveniles select different habitats within a diverse array of wetland types to complete their life-cycle requirements (Patterson 1976; Nelson and Wishart 1988) Hence, the strategy of protecting wetland complexes is likely a sound approach for protecting diversity and enhancing fitness of other species of wetland birds An interesting approach to restoration of wetland complexes was detailed by Taft and Haig (2003) who used historical accounts from early explorers and travelers and contemporary knowledge to develop a profile of the wetlands in the Willamette Valley of Oregon and their use by nonbreeding waterbirds

In general, landscape ecology has figured prominently in management of wetland birds from the beginnings of the national wildlife refuge system to virtually every aspect of habitat protection from local to national scales and beyond In the United States, for example, the humble beginnings of the national wildlife refuge system have expanded from the first tiny refuge set aside in Florida in 1903 (Pelican Island) to a landscape-oriented refuge system unrivaled in the world — as of 2004, there were 632 units in the system, including 545 refuges, spread across all 50 states and most territories The system protects nearly 39 million ha of habitat, of which some 18.5 million ha are wetlands Such protection and management of wetlands continue today, powered by an understanding of why

a landscape-level approach to wetland conservation is a powerful means to protect wetland birds

WETLAND PLANT SUCCESSION

Active habitat management is especially essential for wetlands, which are prone to rapid plant suc-cession or colonization by exotic plants wherein wetland function for wildlife can be completely altered within only one or two growing seasons Manipulation of wetland vegetation is an espe-cially critical focus of waterfowl management, because plants are differentially desirable for food and cover (Baldassarre and Bolen 2006) Other wetland plants can form undesirable monotypes

(e.g., cattails); whereas, still others [e.g., purple loosestrife (Lythrum salicaria)] are invasive exotics

that can seriously diminish the value of a given wetland as wildlife habitat (Thompson et al 1987;

Blossey et al 2001) Hence, the basic concepts of wetland plant succession form the essential found-ation for habitat management in wetlands Successful management must, therefore, be grounded in

an ecologically sound conceptual basis if managers are to understand, test, and hence predictably repeat management initiatives

van der Valk (1981) advanced a Gleasonian view of plant succession in wetlands in that changes are powered by allogenic or external forces, especially the frequency and duration of flooding (i.e., hydroperiod) The effect of these allogenic factors especially depends on the seed bank, which

is the amount of viable seed in the upper few centimeters of the substrate (van der Valk and Davis 1976) However, the propagules of each species in the seed bank germinate differentially in response

to allogenic factors, particularly the extremes of wet and dry conditions Hence, wetland managers must understand the ecology of seed banks, because each management approach (e.g., deep or shallow flooding) will differentially affect the emergence and subsequent growth and persistence of the various species in the seed bank

In a paper especially important toward understanding plant succession in wetlands, van der Valk and Davis (1978) noted that variability in water levels differentially affected germination from the seed bank of prairie wetlands in a manner that led to a description of four basic phases in the cycle of marsh vegetation: (1) dry marsh, (2) regenerating marsh, (3) degenerating marsh, and (4) lake marsh Dry marsh develops during drought and is a time when seeds requiring exposed mudflats (i.e., annuals) will germinate from the seed bank Regenerating marsh occurs when drought ends During the regenerating phase, mudflat species from the dry marsh stage are eliminated, as

is germination of new emergents from the seed bank; free-floating and submergent plants begin to appear wherein the marsh becomes a mix of emergents and submergents The marsh next enters a degenerating phase, which is characterized by a rapid decline in emergents leading to the final phase where the marsh is now largely open water (lake marsh) and dominated by submergent and floating plants Overall, the vegetative community of each marsh phase was a function of water level, but species composition was a function of the seed bank

van der Valk (1981) next used the allogenic approach to develop a model of vegetation succession

in freshwater wetlands Hence, following manipulation of the hydroperiod via control of water levels within a given wetland, managers could reasonably predict the outcome by knowing only three life history attributes of the species in the seed bank or colonizing the site: (1) life span, (2) propagule longevity, and (3) establishment requirements for seedlings The requirements for seedling establishment are especially important but rather simple: (1) species that establish only when and where there is no water, and (2) species that establish when and where there is water van der Valk (1981) also combined the three general life history attributes into a model demonstrating that allogenic influences act as an environmental “sieve” that determines when and where each species will occur in a given wetland Indeed, using the three life history attributes, van der Valk (1981) identified only 12 “types” of wetland plants for his model These models of vegetation dynamics

in prairie wetlands were further refined during the Marsh Ecology Research Program conducted during the 1980s at the Delta Waterfowl and Wetlands Research Station in Manitoba, Canada, which

generated significant new information that ultimately appeared in a comprehensive book, Prairie Wetland Ecology, The Contribution of the Marsh Ecology Research Program (Murkin et al 2000).

The Marsh Ecology Research Program led to new and more refined models of wetland vegeta-tion dynamics, again using the idea of environmental filters, especially changes in water levels As with earlier models, hydroperiod was the major factor affecting wetland vegetation, but the effect of hydroperiod is modified by subtleties of soil moisture, temperature, and salinity van der Valk (2000) thus refined earlier models by adding tolerance of a given species to water depth The new model thus recognized four types of plants in relation to water depth: (1) annuals, (2) wet-meadow spe-cies, (3) emergents, and (4) submergents Mudflat species only occur when sediments are exposed; whereas, wet-meadow species can tolerate short intervals of standing water but not long-term inund-ation Emergents, in contrast, can tolerate permanent flooding and periods without standing water; whereas, submergents generally require permanent water

Obviously, these changes in wetland plant communities affect marsh physiognomy, which in turn affects use of wetlands by wildlife For example, shorebirds generally use shallow water (0–

<25% (Helmers 1992, 1993; Collazo et al 2002) Small species of shorebirds (i.e., Calidris spp.)

require especially shallow water (0–4 cm); hence, accessible habitat for these species might only

be a small proportion of a given wetland For example, only 21–22 ha (13%) of 161-ha managed impoundment at Pea Island National Wildlife Refuge in North Carolina contained habitat in the

0–8 cm range deemed important for foraging dunlins (Calidris alpina) and semipalmated sandpipers (Calidris pusilla; Collazo et al 2002) In contrast, ducks generally prefer deeper water (Fredrickson

and Taylor 1982) Further still, drawdowns scheduled during the breeding season of wading birds can concentrate their prey sources, which increases the foraging opportunities for adult birds feeding their nestlings (Parsons 2002) In addition, various types and densities of emergent vegetation provide highly suitable nest sites for an array of wetland birds such as bitterns, rails, coots, gallinules, waterfowl, and others

THE ROLE OF MODELS

In comparison to the overall field of ecology, “modelers” are relative newcomers Modelers, however, are now quite advanced in creating models that describe patterns in nature, whether they focus on habitat, populations, or both In other words, models have come of age For example, models have driven the development of two important concepts familiar to almost all wildlife managers and conservation biologists: population viability analysis and metapopulation dynamics Indeed, the importance of models in the decision-making process of conservation in general has been stated as follows: “In conservation, predicting the future behavior of a population or system under different management programs is of paramount interest, and no credible prediction is possible without a formal or informal model of the system” (Beissinger et al 2006, 3) The habitat models of van der Valk (1981, 2000) were reviewed above and demonstrated the utility of models in predicting plant succession in wetlands Hence, this section focuses on some of the relevant demographic models that relate specifically to waterbirds and their habitats For birds in particular, the 2006 Ornithological

Monograph Modeling Approaches in Avian Conservation and the Role of Field Biologists is especially

relevant and notes “Use of models in avian conservation may not be a panacea, but neither is it a passing fancy Thus, modelers and field biologists increasingly depend on one another to achieve effective conservation” (Beissinger et al 2006, 40) This excellent publication forms the basis for much of the following discussion

To begin, Beissinger et al (2006) discuss the general form of ecological models, highlighting the approach and application of six types of models especially useful in avian conservation: (1) determin-istic, single-population matrix models; (2) stochastic population viability analysis (PVA) for single populations; (3) metapopulation models; (4) spatially explicit models; (5) genetic models; and (6) species distribution models Overall, their publication is perhaps the best available in reviewing models and their applicability in guiding conservation decisions on birds in general, and space does not allow such a review here Hence, in this section, I provide examples where models have proven especially useful in guiding conservation actions associated with wetland birds

A radiotelemetry study of mallards nesting in North Dakota, for example, generated an important model that identified a 15% nest success rate as necessary to maintain mallard populations in agri-cultural regions (Cowardin et al 1985) Hoekman et al (2002) later expanded this and other efforts

by using a variety of both published and unpublished data on female mallards to generate stage-based matrix models that were subjected to sensitivity analyses to examine the relative importance

of vital population parameters on population growth rates Nest success explained most (43%) of the population growth, followed by adult survival during the breeding season (19%), and survival

of ducklings (14%) Nonbreeding survival, in contrast, only accounted for 9% of the variation in

population growth Overall, predation on the breeding grounds was deemed the proximate factor most limiting mallard population growth Such sensitivity analyses of population data are especially significant, because they can identify key life cycle stages most influential on population growth, which can then act as a focus for management (Beissinger et al 2006)

Flint et al (1998) used demographic models to assess the effects of survival and reproduction

on the population dynamics of northern pintails (Anas acuta) breeding on the Yukon-Kuskokwim

Delta in Alaska Population parameters indicated that 13% of the females produced all of the young

in the population, and that each female produced an average of 0.16 young females per nesting season Adult female survival had the greatest effect on population growth rate (0.8825), followed

by 0.1175 for both reproductive success and first-year survival However, the resultant population projection model suggested that the population was declining rapidly, and that nest success and duckling survival each needed to increase about 40% for the population to stabilize

Stochastic, single population models especially see use in predicting extinction likelihood via

approach to model viability of piping plover (Charadrius melodus) populations on the Great Plains

and noted a strong probability for extinction in the next 100 years, barring significant conservation

action Similarly, Reed et al (1998) used PVA to assess the endangered Hawaiian stilt (Himantopus mexicanus knudseni) Their analysis identified nest failure and adult survival as important factors

affecting population growth, noting that the population was likely to go extinct, again, without significant conservation efforts

These and other models that focused on waterfowl have strong ramifications for conservation For example, managers could affect the two important variables influencing Hawaiian stilt populations by controlling predators and stabilizing water levels (Reed et al 1998) Flint et al (1998) recommended that managers seeking to increase populations of northern pintails should focus their efforts on increasing adult survival in general, which could be achieved by focusing harvest on nonreproductive

or reproductively unsuccessful segments of the population (Clark et al 1988) The results from Hoekman et al (2002) also support the idea that management should focus on increasing survival of females during the breeding season, because population growth is highly sensitive to adult survival,

was supported by Blums and Clark (2004), who studied the effect of female age and other factors

on the lifetime reproductive success of three species of European ducks Their study reported that the number of breeding attempts was most strongly correlated with lifetime reproductive success Thus, adult survival is especially important to overall population growth, because surviving females have more opportunities to attempt breeding efforts and therefore encounter conditions suitable for duckling survival

A second major use of models in waterbird conservation is to generate predictors of habitat quality that can affect reproductive parameters of interest Such an approach can be an effective guide for management actions and efficiently target scarce conservation dollars For example, mod-els developed by Bancroft et al (2002) showed that abundance of four species of wading birds

in the Florida Everglades was related to water level and vegetation community, and there was a threshold of water depth above which wading bird abundance would decline Such findings have major ramifications for restoration efforts in the Everglades, which is of national concern Accord-ingly, Bancroft et al (2002) used their results to recommend that restoration efforts result in more natural hydrologic cycles and slough habitat, which together would improve foraging habitat for wading birds An earlier study by Frederick and Collopy (1989) used logistic regression models to assess water levels in relation to the nesting success of five species of wading birds in the Everglades, noting that ibises were especially affected by water-level fluctuations Overall, general habitat mod-els for the Everglades have long demonstrated that the pristine system was characterized by longer periods of inundation over larger areas than occurs today under a managed and altered ecosystem (Fennema et al 1994) However, Curnutt et al (2000) later used spatially explicit species index mod-els to compare the response of long-legged waders and other wetland birds to different management

scenarios, concluding that no one management scenario was best for all species Nonetheless, their work demonstrates the utility and role of models in restoration of one of the world’s most famous wetlands

Royle et al (2002) generated a two-state model containing wet and dry states of prairie pothole wetlands, the results of which predict the wet probability of a given basin and the amount of water in that basin The model is especially useful in estimating the number of wet basins and the subsequent amount of water likely to occur over a given spatial region Such predications are significant, because wetland conditions are correlated with important demographic parameters such as population size and age structure of fall waterfowl populations, which in turn affect harvest management strategies (Johnson et al 1997) Among other uses, the model could guide management actions effectively, because it could characterize habitat structure at any given point on the landscape

Reynolds et al (2001) used models to evaluate the effect of the Conservation Reserve Program (CRP) on duck production in the Prairie Pothole Region of the United States Their models were used

to compare nest success and recruitment for five ducks species during peak years of CRP (1990–94)

in comparison to a simulated scenario where cropland replaced CRP cover Results were dramatic: Nest success was 46% higher and recruitment 30% higher with CRP versus cropland cover on the landscape, resulting in an estimated 12.4 million additional recruits from their study areas Such findings are critical to agricultural policy, because they demonstrate the effectiveness of a major federal agriculture program, which has significant ramifications outside the Prairie Pothole Region:

Relative to shorebirds, Collazo et al (2002) used models to identify water level targets that maximized accessible habitat for species wintering at two national wildlife refuges on the Atlantic Coast They further noted how estimates of habitat accessibility, along with turnover rates of prey bases, are essential to establish and then implement management goals for shorebirds

TAXONOMY AND PHYLOGENETIC SYSTEMATICS

Every wildlife biologist is familiar with the concepts of taxonomy, having spent countless hours

as an undergraduate or graduate student memorizing genus and species names, as well as families, orders, and more in association with typical vertebrate ecology courses such as ornithology and mammalogy and a plant-oriented course such as systematic botany Although these classification approaches produced scenarios of ancestry and evolutionary relationships among taxa, the resultant taxonomic schemes could not be subjected to critical analysis In contrast, the science of modern phylogenetic systematics seeks to empirically capture the orderly relatedness among similar taxa, which has resulted from patterns of phylogenetic ancestry and descent (Eldredge and Cracraft 1980; Cracraft 1981) In essence, a phylogenetic systematist maps the path of evolution by looking at the intrinsic features of organisms, with the goal of developing a classification that represents the true ancestry (i.e., historical “traits”) and relatedness of those organisms The resultant classification reflects relationships among organisms that are familiar to all biologists: Species within a genus are more closely related than species assigned to another genus, family, or order

Such an approach to taxonomy is significant, because true phylogenies can be used to analyze additional evolutionary patterns exhibited by ecomorphological characteristics such as body mass, clutch size, mating systems, propensity for hybridization, sexual dimorphism, diet, and nest-site selection, among others In other words, if groups of species are related by a set of morphological

or molecular characteristics, then relatedness should also be reflected ecologically Hence,

phylo-geny is seeing new and exciting potential in conservation detailed in books such as Phylophylo-geny and Conservation (Purvis et al 2005).

The use of phylogenetic diversity is gaining currency as a metric for conservation of evolutionary history (Mooers et al 2005), which is beyond our scope here However, other aspects associated with phylogenetic concept of systematics have wide applicability at the management level For example,