Why monitoring matters
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Bird Conservation↗
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A different kind of census: A field guide to nongame bird monitoring programs
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Bird Conservation↗
Methodology
Following the approach developed by Gregory and van Strien (2010), State of the Birds reports focus on composite summaries of population change for collections of species that share common primary habitat or taxonomic affinity. In this report, we provide composite indexes for habitat-obligate species as defined in earlier reports (Grassland, Aridland, Eastern Forest and Western Forest), for several taxonomic-based groups (Shorebirds, Waterbirds, Geese and Swans, Sea Ducks, and Dabbling/Diving Duck species), and for species on our Tipping Point list with adequate data. Lists of species included in each habitat-obligate group are presented as supplemental material at StateoftheBirds.org.
Report↗
Forest bird populations at the Big Island National Wildlife Refuge Complex, Hawai'i
E ndemic Hawaiian forest birds have experienced dramatic population declines. The Big Island National Wildlife Refuge Complex (Refuge Complex) was established for the conservation of endangered forest birds and their habitats. Surveys have been conducted at two units of the Refuge Complex to monitor forest bird populations and their response to management actions. We analyzed survey data from 1987 to 2019 at the Hakalau Forest Unit (HFU) and from 1995 to 2019 at the Kona Forest Unit (KFU). We analyzed three strata at HFU: open-forest, closed-forest, and afforested-pasture, and two strata at KFU: upper (>1,524 m elevation) and lower (<1,524 m). In all years, ‘i‘iwi Vestiaria coccinea , ‘apapane Himatione sanguinea , and Hawai'i ‘amakihi Chlorodrepanis virens virens were the most abundant species at HFU. Three endangered forest bird species, Hawai'i ‘ākepa Loxops coccineus , ‘alawī Loxops mana (also known as Hawai'i creeper) and ‘akiapōlā‘au Hemignathus wilsoni , had much lower densities. The most abundant species at KFU was ‘apapane, followed by Hawai'i ‘amakihi at much lower densities. We found a continuation of several trends observed in previous analyses at HFU up to 2012, with most species’ trends upward in afforested-pasture stratum, stable in the open-forest stratum, and downward in the closed-forest stratum. However, more species were showing downward trends in all three strata during the most recent decade. Results were mixed at KFU, with most species’ trends downward in the upper stratum and upward in the lower stratum. Populations of endangered species were either locally extirpated at KFU or in numbers too low to reliably estimate population abundance. The Refuge Complex is important for conservation of forest birds on Hawai'i Island. Our results show that HFU supports the majority of three endangered forest bird species. Threats to forest birds at the Refuge Complex appear to be having a negative impact. These threats include habitat loss, disease, feral ungulates, and nonnative predators. Continuing and enhancing management actions, such as forest restoration and removal of invasive species, could help mitigate these impacts and allow the Refuge Complex to remain a key site for forest bird conservation in Hawai'i.
Hawaii↗
Habitat and landscape effects on abundance of Missouri's grassland birds
Of 6 million ha of prairie that once covered northern and western Missouri, <36,500 ha remain, with planted, managed, and restored grasslands comprising most contemporary grasslands. Most grasslands are used as pasture or hayfields. Native grasses largely have been replaced by fescue ( Festuca spp.) on most private lands (almost 7 million ha). Previously cropped fields set aside under the Conservation Reserve Program (CRP) varied from a mix of cool-season grasses and forbs, or mix of native warm-season grasses and forbs, to simple tall-grass monocultures. We used generalized linear mixed models and distance sampling to assess abundance of 8 species of breeding grassland birds on 6 grassland types commonly associated with farm practices in Missouri and located in landscapes managed for grassland-bird conservation. We selected Bird Conservation Areas (BCAs) for their high percentage of grasslands and grassland-bird species, and for <5% forest cover. We used an information-theoretic approach to assess the relationship between bird abundance and 6 grassland types, 3 measures of vegetative structure, and 2 landscape variables (% grassland and edge density within a 1-km radius). We found support for all 3 levels of model parameters, although there was less support for landscape than vegetation structure effects likely because we studied high-percentage-grassland landscapes (BCAs). Henslow's sparrow ( Ammodramus henslowii ) counts increased with greater percentage of grassland, vegetation height-density, litter depth, and shrub cover and lower edge density. Henslow's sparrow counts were greatest in hayed native prairie. Dickcissel ( Spiza americana ) counts increased with greater vegetation height-density and were greatest in planted CRP grasslands. Grasshopper sparrow ( A. savannarum ) counts increased with lower vegetation height, litter depth, and shrub cover. Based on distance modeling, breeding densities of Henslow's sparrow, dickcissel, and grasshopper sparrow in the 6 grassland types ranged 0.9–2.6, 1.4–3.2, and 0.1–1.5 birds/ha, respectively. We suggest different grassland types and structures (vegetation height, litter depth, shrub cover) are needed to support priority grassland-bird species in Missouri.
Journal of Wildlife Management↗
The importance of floodplain forests in the conservation and management of neotropical migratory birds in the Midwest
Bottomland forests of the Central Forest Region of the Upper Midwest are found primarily on the floodplains of large rivers and include at least six types of forest communities. Birds breeding in bottomland forests are affected by extensive variation in latitude, climate, hydrology, forest succession, and change caused by anthropogenic disturbances. The floodplain forest bird community differs in species composition and in relative abundance from adjacent upland habitats. High abundances of some species are found in the floodplain and some species, such as the prothonotary warbler, brown creeper, yellow-billed cuckoo, yellow-bellied sapsucker, and great crested flycatcher, show a clear preference for floodplain forests. Studies of nesting success indicate that, for some species, nest success may be higher in the floodplain than in the uplands. Floodplain birds face threats due to large-scale loss of floodplain forest habitat. Conservation efforts should focus on restoring degraded floodplains by maintaining high tree species diversity and wide corridors. To accomplish this, the underlying hydrodynamics which support a diverse floodplain forest habitat may need to be restored. Large, contiguous tracts of floodplain and upland forests should be maintained where they exist and restored in other locations. This will provide some high quality habitat for area-sensitive neotropical migratory birds (NTMBs) in agricultural landscapes where small, scattered forest fragments are the rule. Future research efforts should examine the importance of floodplain forests in maintaining populations of neotropical migrants, especially birds experiencing population declines in adjacent uplands.
Book chapter↗
Forest bird monitoring protocol for strategic habitat conservation and endangered species management on O'ahu Forest National Wildlife Refuge, Island of O'ahu, Hawai'i
This report describes the results of a pilot forest bird survey and a consequent forest bird monitoring protocol that was developed for the O'ahu Forest National Wildlife Refuge, O'ahu Island, Hawai'i. The pilot survey was conducted to inform aspects of the monitoring protocol and to provide a baseline with which to compare future surveys on the Refuge. The protocol was developed in an adaptive management framework to track bird distribution and abundance and to meet the strategic habitat conservation requirements of the Refuge. Funding for this research was provided through a Science Support Partnership grant sponsored jointly by the U.S. Geological Survey (USGS) and the U.S. Fish and Wildlife Service (USFWS).
Hawai'i↗
Contributions of the Conservation Reserve Program to populations of breeding birds in North Dakota
Previous studies have shown that habitat provided by the Conservation Reserve Program (CRP), a feature of the 1985 farm bill, is used by many birds. The present study quantitatively assesses the importance of the CRP by estimating changes in breeding-bird populations of North Dakota projected if CRP land would revert to cultivation. Of 18 species that were common in CRP or crop fields or both, 12 were more abundant in CRP habitats. Six of these species had suffered significant population declines during 1967-1990, according to the North American Breeding Bird Survey. In contrast, none of the six species that were more common in cropland than in CRP fields had declined significantly. Termination of the Conservation Reserve Program and a return of enrolled land to cultivation is projected to cause population declines in North Dakota exceeding 17% for Sedge wren (Cistothorus platensis), Grasshopper sparrow (Ammodramus savannarum), Savannah Sparrow (Passerculus sandwichensis), Dickcissel (Spiza americana), and Lark Bunting (Calamospiza melanocorys).
The Wilson Bulletin↗
Relationship of obligate grassland birds to landscape structure in Wisconsin
Conservation plans for grassland birds have included recommendations at the landscape level, but species' responses to landscape structure are variable. We studied the relationships between grassland bird abundances and landscape structure in 800-ha landscapes in Wisconsin, USA, using roadside surveys. Of 9 species considered, abundances of only 4 species differed among landscapes with varying amounts of grassland and forest. Landscape variables explained <20% of variation in abundances for 4 of the 5 rarest species in our study. Our results suggest landscape-based management plans for grassland birds might not benefit the rarest species and, thus, plans should incorporate species-specific habitat preferences for these species.
Journal of Wildlife Management↗
Conceptual ecological model for management of breeding shrubland birds in the Mid-Atlantic Region
While grassland birds have become the focus of increased conservation activities, the status of birds occupying shrubland habitats has received relatively little attention (Hunter et al. 2001). Yet, in eastern North America, shrubland birds exhibited consistent population declines during the past 40 years, based on data from the North American Breeding Bird Survey (Pardieck and Sauer 2001). These population declines primarily reflect large-scale changes in land use patterns during the previous century (Lorimer 2001). Large areas of marginal farmland were abandoned and underwent secondary succession during the first half of the twentieth century, producing abundant successional habitats favored by shrubland birds. As these habitats matured, combined with strict fire-suppression policies (Hunter et al. 2001), shrublands succeeded into mature forests, and shrubland bird communities were replaced by woodland birds (Irland 1982; Askins 1993). For example, while nearly 29% of New England forests were classified as sapling stage in 1950, only 8% remained at that stage in the 1980s (Askins 1993). The trend towards forest maturation and loss of shrubland habitats continues, yet concerted conservation activities have not been directed to benefit declining shrubland bird populations. The National Park Service (NPS) could contribute to shrubland bird conservation in the Mid- Atlantic Region. The NPS maintains a number of historic sites and former battlefields managed for their cultural significance but also support wildlife populations. Many of these “cultural parks” maintain open landscapes, recreating land use patterns existing at the times of the historical events. While these open landscapes are frequently managed grasslands, some parks also support successional habitats that could be managed to benefit shrubland birds. In 2005, the NPS initiated a project exploring the potential of “cultural parks” to support significant breeding grassland and shrubland bird communities. This project involved parks within three NPS Inventory and Monitoring Program (I&M) networks, Mid-Atlantic, National Capital, and Eastern Rivers and Mountains. Five parks were selected for the initial focus of this study, all of which maintain open landscapes for interpreting historic events. Most parks were selected because they contain the most extensive grassland habitats within their networks, although some also support shrubby successional habitats. The five parks included in this study are Antietam National Battlefield, Fort Necessity National Battlefield, Gettysburg National Battlefield, Manassas National Battlefield, and Monocacy National Battlefield. This conceptual ecological model is one product of this project. The information presented below allows NPS network coordinators to understand which factors should be considered when making decisions concerning shrubland management within their networks. This model provides park resource managers with information on shrubland ecology in the Mid-Atlantic Region, the ecological requirements of shrubland birds likely to occur in their parks, and management issues influencing whether significant breeding populations can occupy shrublands created and maintained in the parks. Resource managers can then make informed decisions concerning their ability to create and maintain shrubland habitats. The emphasis of this conceptual model is restricted to management of breeding shrubland birds. Additional species occur during migration and winter, and habitat requirements of shrubland birds during nonbreeding seasons may differ from those described for the breeding season.
Technical Report↗
Structured decision making to prioritize regional bird monitoring needs
Conservation planning for large ecosystems has multiple benefits but is often challenging to implement because of the multiple jurisdictions, species, and habitats involved. In addition, decision making at large spatial scales can be hampered because many approaches do not explicitly incorporate potentially competing values and concerns of stakeholders. After the Deepwater Horizon oil spill, establishing baselines was challenging because of (1) variation in study designs, (2) inconsistent use of explicit objectives and hypotheses, (3) inconsistent use of standardized monitoring protocols, and (4) variation in spatial and temporal scope associated with avian monitoring projects before the spill. Herein, we show how the Gulf of Mexico Avian Monitoring Network members used structured decision making to identify bird monitoring priorities. We used multiple tools and techniques to clearly define the problem and stakeholder objectives and to identify bird monitoring priorities at the scale of the entire northern Gulf of Mexico region. Although our example is specific to the northern Gulf of Mexico, this approach provides an example of how stakeholder values can be incorporated into the coordination process of broad-scale monitoring programs to address management, restoration, and scientific questions in other ecosystems and for other taxa.
INFORMS Journal on Applied Analytics↗
Pacific island landbird monitoring report, Kalaupapa National Historical Park, 2021
In 2021, landbird surveys were conducted at Kalaupapa National Historical Park on the island of Molokaʻi to assess changes in species composition, distribution, and population densities since 2005. Point-transect distance sampling surveys were conducted on six transects at 50 landbird monitoring stations within an 1,834-hectare area. A total of nine landbird species were detected, with the ʻApapane ( Himatione sanguinea ) the only endemic Hawaiian species detected. Sufficient detections of six species allowed for population density and abundance estimates, which were compared to 2005 estimates using a two-sample z-test. The abundance of ʻApapane declined by 57% to 2,476 ± 729 (SE) birds in 2021 compared to 2005. Population densities of the House Finch ( Haemorhous mexicanus ), Japanese Bush Warbler ( Horornis diphone ), Warbling White-eye ( Zosterops japonicus ), and White-rumped Shama ( Copsychus malabaricus ) were also lower in 2021 than in 2005, but comparisons were inconclusive. Since 2005, the Red-billed Leiothrix ( Leiothrix lutea ) irrupted within the survey area to an estimated abundance of 11,088 ± 1,208 birds. The Warbling White-eye was the most abundant species, with an estimated 101,724 ± 11,692 birds. Surveyors failed to detect the Hawaiʻi ʻAmakihi ( Chlorodrepanis virens ), which has become increasingly rare on Molokaʻi. The federally threatened ʻIʻiwi ( Drepanis coccinea ) was last seen on Molokaʻi in 2010, further raising concerns about its potential extirpation. The Olomaʻo ( Myadestes lanaiensis ), an endemic thrush, has not been detected since 1980 and is likely extinct. These findings show the ongoing shift toward non-native bird communities and highlight the challenges of conserving native forest birds amidst widespread avian malaria transmission, introduced predators, and extensive habitat degradation.
Hawaii↗
Book review: Bird census techniques, Second edition
Conservation concerns, federal mandates to monitor birds, and citizen science programs have spawned a variety of surveys that collect information on bird populations. Unfortunately, all too frequently these surveys are poorly designed and use inappropriate counting methods. Some of the flawed approaches reflect a lack of understanding of statistical design; many ornithologists simply are not aware that many of our most entrenched counting methods (such as point counts) cannot appropriately be used in studies that compare densities of birds over space and time. It is likely that most of the readers of The Condor have participated in a bird population survey that has been criticized for poor sampling methods. For example, North American readers may be surprised to read in Bird Census Techniques that the North American Breeding Bird Survey 'is seriously flawed in its design,' and that 'Analysis of trends is impossible from points that are positioned along roads' (p. 109). Our conservation efforts are at risk if we do not acknowledge these concerns and improve our survey designs. Other surveys suffer from a lack of focus. In Bird Census Techniques, the authors emphasize that all surveys require clear statements of objectives and an understanding of appropriate survey designs to meet their objectives. Too often, we view survey design as the realm of ornithologists who know the life histories and logistical issues relevant to counting birds. This view reflects pure hubris: survey design is a collaboration between ornithologists, statisticians, and managers, in which goals based on management needs are met by applying statistical principles for design to the biological context of the species of interest. Poor survey design is often due to exclusion of some of these partners from survey development. Because ornithologists are too frequently unaware of these issues, books such as Bird Census Techniques take on added importance as manuals for educating ornithologists about the relevance of survey design and methods and the often subtle interdisciplinary nature of surveys. Review info: Bird Census Techniques, Second Edition. By Colin J. Bibby, Neil D. Burgess, David A. Hill, and Simon H. Mustoe. 2000. Academic Press, London, UK. xvii 1 302 pp. ISBN 0- 12-095831-7.
Condor↗
Climate change and coastal wetland salinization: Physiological and ecological consequences for Arctic waterfowl
Coastal wetland salinization related to warming climate has the potential to impact ecological systems globally. In Alaska, the Yukon-Kuskokwim Delta (YKD) supports large concentrations of breeding water birds and is an ecologically important area for conservation of migratory bird biodiversity. On the YKD, the majority of waterfowl nest in low elevation coastal tundra where storm surges drive saline water into terrestrial wetland habitats. Because newly hatched water birds lack functional salt glands to process saline water, salinization may negatively impact their growth and survival. We investigated potential demographic impacts of wetland salinization by conducting controlled physiological experiments to determine consequences of saline water exposure to spectacled Somateria fischeri and Steller's eider Polysticta stelleri ducklings, and analysed habitat suitability based on experimentally defined tolerance thresholds and sampled wetland salinity levels. We found physiological and behavioural pathologies in <1 week old ducklings at exposure levels of 6 parts per thousand (ppt), and found some evidence of reduced growth in ducklings first exposed after 1 week of age. We conclude that the acute toxicity threshold for ducklings <1 week of age is ≤6 ppt. We found that the area of coastal tundra where wetland salinity exceeded 6 ppt varied considerably among years, suggesting that some portion of the breeding range is unsuitable for rearing ducklings in some years. However, we also found that most eiders in most years nested in areas with salinity at or exceeding the tolerance threshold for ducklings, suggesting that nesting eiders do not appear to avoid saline habitats. We suggest that localized fresh water refugia currently may allow resilience to salinization during the critical period. Understanding how species and habitats respond to climate driven changes is essential for predicting future patterns of distribution and abundance, and is necessary for making informed decisions about conservation priorities. Our study provides insights into the extent of wetland salinization in Alaska, mechanism of impact and current ecological consequences on avian communities depending on these habitats. With ongoing climate change, the probability of species crossing physiological tolerance thresholds of wetland salinity may change in the future.
Functional Ecology↗
Waterfowl and wetland birds
The future of wetland bird habitat and populations is intrinsically connected with the conservation of rangelands in North America. Many rangeland watersheds are source drainage for some of the highest functioning extant wetlands. The Central and Pacific Flyways have significant overlap with available rangelands in western North America. Within these flyways, the importance of rangeland management has become increasingly recognized by those involved in wetland bird conservation. Within the array of wetland bird species, seasonal habitat needs are highly variable. During the breeding period, nest survival is one of the most important drivers of population growth for many wetland bird species and rangelands often provide quality nesting cover. Throughout spring and fall, rangeland wetlands provide key forage resources that support energetic demands needed for migration. In some areas, stock ponds developed for livestock water provide migration stopover and wintering habitat, especially in times of water scarcity. In the Intermountain West, drought combined with water demands from agriculture and human population growth are likely headed to an ecological tipping point for wetland birds and their habitat in the region. In the Prairie Pothole Region, conversion of rangeland and draining of wetlands for increased crop production remains a significant conservation issue for wetland birds and other wildlife. In landscapes dominated by agricultural production, rangelands provide some of the highest value ecosystem services, including water quality and wetland function. Recent research has shown livestock grazing, if managed properly, is compatible and at times beneficial to wetland bird habitat needs. Either directly, or indirectly, wetland bird populations and their habitat needs are supported by healthy rangelands. In the future, rangeland and wetland bird managers will benefit from increased collaboration to aid in meeting ultimate conservation objectives.
Book chapter↗
Using the North American Breeding Bird Survey as a tool for conservation: A critique of Bart et al. (2004)
Bart et al. (2004) develop methods for predicting needed samples for estimation of long-term trends from Count survey data, and they apply these methods to the North American Breeding Bird Survey (BBS). They recommend adding approximately 40% more survey routes ill the BBS to allow for estimation of long-term (i.e., 20 year) trends for a collection of species. We critique several aspects of their analysis and suggest that their focus on long-term trends and expansion of the present survey design will provide limited benefits for conservation because it fails to either enhance the credibility of the survey or better tie the survey to regional management activities. A primary innovation claimed by Bart et al. (2004) is the incorporation of bias in estimation of study planning. We question the value of this approach, as it requires reliable estimates of range of future bias. We show that estimates of bias used by Bart et al. (2004) are speculative. Failure to obtain better estimates of this bias is likely to compromise the credibility of future analyses of the survey. We also note that the generic analysis of population trends that they provide is of questionable validity and is unlikely to be relevant for regions and species of management concern.
Journal of Wildlife Management↗
Forest bird populations at the Big Island National Wildlife Refuge Complex, Hawai‘i
Endemic Hawaiian forest birds have experienced dramatic population declines. The Big Island National Wildlife Refuge Complex (BINWRC) was created for conservation of endangered Hawaiian forest birds and their habitats. Surveys have been conducted at two units of BINWRC to monitor forest bird populations and their response to management actions. We analyzed survey data from 1987 to 2019 at the Hakalau Forest Unit (HFU) and from 1995 to 2019 at the Kona Forest Unit (KFU). We analyzed three strata at HFU: open-forest, closed-forest, and pasture, and two strata at the KFU: upper (>1524 m elevation) and lower (<1524 m). In all years, ‘i‘iwi (Drepanis coccinea), ‘apapane (Himatione sanguinea), and Hawai‘i ‘amakihi (Chlorodrepanis virens virens) were the most abundant species at HFU. The three endangered forest bird species, Hawai‘i ‘ākepa (Loxops coccineus), ‘alawī (Loxops mana, also known as Hawai‘i creeper) and ‘akiapōlā‘au (Hemignathus wilsoni), had much lower densities. The most abundant species at KFU was ‘apapane, followed by Hawai‘i ‘amakihi and warbling white-eye (Zosterops japonicus) at much lower densities. At HFU we found a continuation of several trends observed in previous analyses from 1987–2012, with most species’ trends upward in pasture stratum, stable in the open-forest stratum, and downward in the closed-forest stratum. However, when we looked at the most recent decade at HFU, more species were showing downward trends in all three strata. At KFU results were mixed, with more species’ trends downward in the upper stratum and more species’ trends upward in the lower stratum. Populations of endangered forest species were either locally extirpated at KFU or in numbers too low to reliably estimate population densities. Both units in the BINWRC are important for conservation of forest birds on Hawai‘i Island, and our results show that HFU supports the majority of the three endangered forest bird species found on Hawai‘i Island. Our analysis also shows the importance of continuous monitoring and timely analysis to track forest bird populations. With the additional data provided by continued surveys, we determined conclusive population trends for species whose trends were previously inconclusive. Knowing current population densities, abundances, and trends allows managers to evaluate and adapt management actions to support forest bird conservation at the BINWRC.
Hawaii↗