Proceedings of the Fourth International
Partners in Flight Conference: Tundra to Tropics
419–425
CONSERVATION OPPORTUNITY ASSESSMENT FOR RARE BIRDS
IN THE MIDWESTERN UNITED STATES: A PRIVATE LANDS
IMPERATIVE
WAYNE E. THOGMARTIN1 AND JASON J. ROHWEDER
USGS Upper Midwest Environmental Sciences Center, 2630 Fanta Reed Road, La Crosse, Wisconsin
54603, USA
Abstract. Applying conservation in an efficient manner is desirable in a constrained economic climate. Mapped predictions of species abundance may allow the spatial targeting of focal areas for
conservation, increasing the efficiency of conservation application. We overlayed mapped patterns in
predicted relative abundance, from hierarchical spatial count models for 11 species of conservation
concern, against digital data layers describing federal-, tribal-, and state-managed lands to identify
the relative contribution of governmental agencies in the conservation of rare bird habitat in the
Prairie Hardwood Transition (Bird Conservation Region 23). The proportion of predicted populations under direct governmental jurisdiction differed by habitat guild, with 0.5%, 1.3%, and 1.0%
of grassland birds occurring on federal-, state-, and tribal-managed lands, respectively, and 2.8%,
17.9%, and 3.1% of forest birds occurring on federal-, state-, and tribal-managed lands, respectively.
Irrespective of habitat guild, the vast majority of most species were predicted to occur on private
lands (with Cerulean Warbler [Dendroica cerulea] as a notable exception). This importance of private
lands for the conservation of rare birds in the midwestern U.S. has profound consequences for how
natural resource agencies should direct their effort if they are to be successful conservators of these
trust resources. The maps of predicted abundances relative to governmentally managed lands that we
provided may be used to prioritize and focus management on private lands in the Prairie Hardwood
Transition. This spatial targeting of conservation effort represents an efficient, accountable, and scientifically justifiable approach to the management of species of conservation concern.
Key Words: Conservation Design, land management, private lands, public land.
PARA LA EVALUACIÓN DE OPORTUNIDADES DE CONSERVACIÓN
DE AVES RARAS EN EL MEDIO OESTE DE ESTADOS UNIDOS: UN
IMPERATIVO DE TIERRAS PRIVADAS
Resumen. Aplicando la conservación de una manera eficiente es deseable en un clima económico limitado. Mapas de la abundancia de especies predicciones puede permitir la orientación espacial de
las áreas focales para la conservación, aumentar la eficiencia de la conservación aplicación. Estamos
superpuestas asignada previsto en los patrones de abundancia relativa, de contar con modelos
jerárquicos espacial de 11 especies de preocupación, en contra de las capas de datos digitales que
describen federales, tribales-, y las tierras administradas por el Estado para determinar la contribución
relativa de los organismos gubernamentales en la conservación de especies raras hábitat de las aves
en la pradera de madera de transición (Conservación de las Aves de la Región 23). La proporción de
la población prevista gubernamentales bajo la jurisdicción directa del hábitat por diferentes gremios,
con el 0,5%, 1,3% y 1,0% de aves de pastizales que ocurren en federal, tribal-, y las tierras administradas por el Estado, respectivamente, y el 2,8%, 17,9%, y el 3,1% de las aves que ocurren en los bosques
federales, tribales-, y las tierras administradas por el Estado, respectivamente. Independientemente
de hábitat gremio, la gran mayoría de la mayoría de las especies se prevé que se produzcan en tierras
privadas (con la Reinita Cerúlea [Dendroica cerulea] como una notable excepción). Esta importancia
de las tierras privadas para la conservación de aves raras en el medio oeste EE.UU. tiene profundas
consecuencias para los recursos naturales de cómo los organismos deberían dirigir sus esfuerzos a fin
de que sean exitosos conservadores confianza de estos recursos. Los mapas de abundancia relativa
para predecir el gobierno gestionadas tierras que siempre se puede utilizar para priorizar y focalizar
la gestión en tierras privadas en la “Pradera” de madera de transición. La orientación espacial de este
esfuerzo de conservación representa un eficiente, responsable y científicamente justificables enfoque
a la gestión de especies de preocupación para la conservación.
1
E-mail: wthogmartin@usgs.gov
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Proceedings of the Fourth International Partners in Flight Conference
INTRODUCTION
Conservation design as articulated by Will et
al. (2005) is a touchstone for avian conservation
in North America. This philosophy consists of
five elements: 1) landscape characterization and
assessment, 2) bird population response modeling, 3) conservation opportunities assessment,
4) optimal landscape design, and 5) monitoring
and evaluation. The efficiency of avian conservation increases when management action can
be directed to areas suitable for the species of
interest. The use of models to predict distributions, occurrences, and abundances of species is
common in ecological studies (Scott et al. 2002,
Fitgerald et al. 2008). These models can be used
to assess species relationships to environmental
variables and to locate potential areas for management or protection.
We previously used hierarchical spatial
count models to map regional patterns in
the predicted relative abundance of 11 rare
birds in the upper midwestern United States
(Thogmartin et al. 2004, 2006, Thogmartin and
Knutson 2007). This modeling approach related
Breeding Bird Survey counts to environmental
covariates, adjusting for nuisances relating to
spatial autocorrelation in survey counts and
observer and year differences. These 11 rare
bird species included six grassland birds (Sedge
Wren [Cistothorus platensis], Savannah Sparrow
[Passerculus
sandwichensis],
Grasshopper
Sparrow [Ammodramus savannarum], Henslow’s
Sparrow [A. henslowii], Bobolink [Dolichonyx
oryzivorus], Eastern Meadowlark [Sturnella
magna]) and five forest birds (Black-billed
Cuckoo [Coccyzus erythropthalmus], Red-headed
Woodpecker [Melanerpes erythrocephalus], Wood
Thrush [Hylocichla mustelina], Golden-winged
Warbler [Vermivora chrysoptera], and Cerulean
Warbler). Similar modeling and mapping has
been conducted for waterfowl and landbirds
in the Prairie Pothole Region (Forcey et al.
2007), for rare warblers in the Appalachians
(Fitzgerald et al. 2008), and for the American
Woodcock across its breeding ground in the
United States (Thogmartin et al. 2007).
With mapped predicted relative abundances
as the basis for our research, we inferred the relative conservation contribution provided by federal, tribal, and state land management agencies
and the proportion of the breeding population
occurring on private lands. This is one aspect of
the third element of the Partners in Flight Five
Elements Process, conservation opportunities
assessment (Will et al. 2005). Understanding the
conservation context of these breeding populations may allow the targeting of specific locations for management, possibly increasing the
economic efficiency as well as the scientific justification of this conservation.
STUDY AREA AND METHODS
The focus of our modeling effort was Bird
Conservation Region 23 (hereafter BCR23),
the Prairie–Hardwood Transition (Fig. 1;
Thogmartin et al. 2004). BCR23 occupies 230,111
km2, stretching from central Minnesota through
central and southern Wisconsin and Michigan,
including small sections of northeastern
Iowa, and northern Illinois and Indiana; Lake
Michigan bisects the region. The predominant
land uses/land covers in this region are row
crop agriculture (36%), grassland (27%), and
deciduous forest (21%). Much of the region is a
rolling plain of loess-mantled ridges over sandstone and carbonate bedrock and pre-Illinoian
ground moraine, contributing to a diversity of
topographic relief and vegetation. BCR23 transitions from beech–maple forest in the north
to agriculture (historically tallgrass prairie) in
the south. There is also a gradient in climate
from north-west to southeast, with climatic differences being most pronounced east of Lake
Michigan.
We used the mapped predictions of hierarchical spatial count models as the basis for our inferences (Thogmartin et al. 2004, 2006, Thogmartin
and Knutson 2007). We overlaid these mapped
predictions against federal-, tribal-, and stateadministered lands in a geographic information
system, ArcGIS 9.2 (Environmental Systems
Research, Inc., Redlands, California, USA). We
used the Protected Areas Database 4 (DellaSala
et al. 2001; www.consbio.org/cbi/projects/
PAD/) as the source of the conservation estate;
this database suggested approximately 9% of the
Prairie Hardwood Transition occurred in one
of these three conserved states. State-managed
lands in this database were largely derived
from state GAP projects (e.g., Wisconsin data
were gleaned from the Wisconsin Department
of Natural Resources).
Unfortunately, states defined their managed lands differently, yielding little consistency in what constituted a state-managed
land. Nevertheless, we used these data as the
best available information for state-level inference. The proportion of the predicted population was calculated for federal, tribal, state, and
private lands. Private lands were all lands not
designated federal, tribal, or state managed, and
included unmapped conservation easements,
county and city conserved lands, industrial forests, and potentially many other lands in various
states of conservation. We tested, with a onesample test of proportions (Zar 1984), whether
Conservation Opportunity Assessment—Thogmartin and Rohweder
421
FIGURE 1. The conservation estate for the Prairie Hardwood Transition (Bird Conservation Region 23) of the
upper midwestern United States. Note the absence of finely resolved lands in Wisconsin as compared to all of
the other states; this difference in the mapped density of conserved lands is indicative of differences in how
lands are defined as conserved by each state.
the proportion of each species-specific population under federal, tribal, or state management
authority was more than could be expected
given the proportion of land occupied by these
management authorities within each state.
RESULTS
The vast majority of the 11 focal bird populations in the Prairie Hardwood Transition were
predicted to occur on private lands outside of
the direct jurisdiction of federal, state, or tribal
land management. The proportion of predicted
populations under direct jurisdiction differed
by habitat guild, with 0.5%, 1.3%, and 1.0% of
grassland birds occurring on federal-, state-,
and tribal-managed lands, respectively, and
2.8%, 17.9%, and 3.1% of forest birds occurring
on federal-, state-, and tribal-managed lands,
respectively. The proportions of populations
occurring on private lands varied between
0.07% (0.00–0.18%; 99% confidence interval)
for Grasshopper Sparrows on tribal-managed
land and 63.04% (61.79–64.27%) for Cerulean
Warblers on state-managed land.
Of the focal grassland species, only Bobolink
on tribal-managed land and Sedge Wren on
federal-managed land were conserved at a
greater proportion than would be expected
by a random allocation of managed land on
the landscape (Fig. 2a). Savannah Sparrow on
tribal-managed lands were conserved in equal
proportion to the presence of tribal lands on the
landscape. Conversely, all other focal grassland
species on all other managed lands were conserved at rates less than would be expected if
managed lands were randomly allocated.
Of the focal forest species, only the Redheaded Woodpecker was conserved less than
would be expected by a random regional allocation of conserved lands (Fig 2b). The vast majority of the predicted population of Cerulean
Warblers occurred on managed lands, principally two state game areas in southwestern
Michigan (Fig. 3).
DISCUSSION
We summarized the predictions of spatial
models of rare bird abundance to infer the relative contribution of federal, tribal, and state
authorities to the management of these species
on their breeding grounds in the upper midwestern United States. Our assessment suggested
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Proceedings of the Fourth International Partners in Flight Conference
FIGURE 2. The predicted proportion of each population of focal grassland a) and forest b) birds in a conserved state differs in the Prairie Hardwood Transition between species and the type of land authority. The
proportion of land under federal (dark gray), tribal (light gray), and state (white) land management is marked
by the dashed lines. Species are Black-billed Cuckoo (BBCU), Bobolink (BOBO), Cerulean Warbler (CERW),
Eastern Meadowlark (EAME), Golden-winged Warbler (GWWA), Grasshopper Sparrow (GRSP), Henslow’s
Sparrow (HESP), Red-headed Woodpecker (RHWO), Savannah Sparrow (SAVS), Sedge Wren (SEWR), and
Wood Thrush (WOTH).
that conservation for focal forest species was
equal to or greater than would be predicted by a
random allocation of managed lands, but focal
grassland species were generally conserved less
than that predicted by chance. Regardless, all of
the focal species except for the Cerulean Warbler
had the greatest proportion of their population
occurring on private lands outside of the conservation estate. This has profound implications
for the management of these rare birds.
For natural resource agencies to be successful conservators of avian trust resources in
the upper midwestern United States, a focus
on populations on private lands is of paramount concern (Knight 1999, Norton 2000).
This private-lands imperative may require an
increasing participation of the private sector in
conservation through philanthropy, land trusts,
conservation easements, private reserves, incentive programs, and other innovative conservation efforts (Yaffee and Wondolleck 2000, James
2002, Goldstein et al. 2006). Other avenues for
conservation on private lands may entail the
imposition of development restrictions (Lovell
and Sunding 2001), an undoubtedly difficult
and controversial prospect (Innes et al. 1998).
Regardless, success in avian conservation will
likely be determined by the ability of governmental agencies to foster and facilitate these private sector efforts.
Conservation Opportunity Assessment—Thogmartin and Rohweder
423
FIGURE 3. The high proportion of the Cerulean Warbler population occurring on conserved lands is a consequence of 55% of the predicted population occurring in Allegan State Game Area, 9% in Barry State Game Area,
and another 4% in Fort Custer Training Ground, in southwestern Michigan.
Admittedly, circumspection of these results
are required, firstly, because the mapped models have not been fully field validated and,
secondly, because populations are dynamic
and expected to change over time in contradiction to the implied static nature of the maps
we produced.
MANAGEMENT IMPLICATIONS
Federal, tribal, and state authorities may
use the overlays of predicted abundance
against management boundaries to target
conservation easements, land acquisition, and
other conservation initiatives directed for the
management of these species. To aid in this
effort, we have developed conservation estate
portfolios for each of the 11 focal species modeled and mapped for the Prairie Hardwood
Transition (e.g., Rohweder and Thogmartin
2007; Fig. 4). We believe this spatial targeting
of conservation effort represents an efficient,
accountable, and scientifically justifiable
approach to the management of species of conservation concern.
ACKNOWLEDGMENTS
Further information relating to this study
can be obtained from http://www.umesc.usgs.
gov/terrestrial/migratory_birds/bird_conservation/. Reference to trade and product names
does not imply endorsement by the U.S. government. This manuscript was made measurably better by the comments of J. A. Fitzgerald,
T. Rich, and W. J. Sadinski.
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