AUTHOR BLOG: Citizen-Science Data and Capture-Mark-Recapture Models to Estimate Numbers of Rare Species

Andrew Dennhardt

Linked paper: Applying citizen-science data and mark–recapture models to estimate numbers of migrant Golden Eagles in an Important Bird Area in eastern North America by A.J. Dennhardt, A.E. Duerr, D. Brandes, and T.E. Katzner, The Condor: Ornithological Applications 119:4, November 2017.

Have you ever looked to the autumn sky above and wondered how many of your favorite feathered friends are out there, as they migrate southward each year? If so, then you are not alone. A common goal in ecology has been to estimate the abundance of wild populations. From basic counts to educated guesses, historically, people have tried it all. During and even before the work of Sir Ronald Fischer, the father of modern statistics, applied mathematics aided in population estimation—for humans and wild animals alike.

F.C. Lincoln (1930) is credited with one of the first modern attempts to approximate population abundance of wild animals based on a sample of marked individuals (Bailey 1952, Le Cren 1965). The premise of his approach, co-credited to C. G. Johannes Petersen (1894) and commonly called capture-mark-recapture (CMR), was simple: trap a random set of animals of the same species in an area, mark those you caught with a unique tag, release them back into the wild for a period of time, return to the same area once more and randomly trap individuals of that same species again, and record which previously tagged individuals, if any, came back to the area. In brief, when you know the proportion of individuals you recaptured the second time, you can assume that you trapped the same proportion of the total population when you trapped the first time. The math is straightforward, too: if you have an initial sample of animals captured, marked, and released back into the wild, M, and multiply that by the total number of animals sampled a second time, n, then you can divide that quantity by the number of marked animals in that second sample, m, and approximate true population size, N.

In our paper, we used modern statistical advancements in CMR to estimate abundance of Golden Eagles (Aquila chrysaetos), a species of conservation concern in the United States, using an unusual approach. In effect, we did not physically capture, mark, or recapture individual animals in the wild; rather, we did so virtually in a computing environment with the help of observational data collected by some savvy citizen-scientists.

Golden Eagles in eastern North America face lethal and sub-lethal threats, many of which are human caused. However, these eagles are rarely seen, broad-ranging, and difficult to capture in the wild because they often avoid areas of human activity. Despite this fact, citizen-scientists observe Golden Eagles frequently and regularly during their annual spring and autumn migrations in Pennsylvania, U.S.A. Moreover, Golden Eagle movements are highly stereotyped, especially in autumn, bringing them within a few hundred meters of hawk counters on ridgetops in the Appalachian Mountains. Better still, because of past telemetry studies, we know how fast Golden Eagles fly when they migrate. Hawk counters collect their data on Golden Eagles and other migrant species and archive their observations in an online database, hawkcount.org. With assistance from managers of the archive, our research team gained permission and access to download historic count data on migrating Golden Eagles observed using the Kittatinny Ridge during their peak migration period, November, over a 10 year period from 2002 to 2011.

Now, here’s where things get really exciting (well, they do for me, at least!). Because (a) historic hawk-count data included information on the timing of Golden Eagles migrating southward past monitoring sites along the Kittatinny, (b) telemetry data gave us an idea of how fast they fly while migrating in autumn, and (c) we could measure the distance between each of the monitoring sites they passed, we could then estimate how long it would take eagles to travel between pairs of sites. Using a customized computer program, we matched records of Golden Eagles together, from site to site, such that we could know when observers at one site counted a bird that had probably been counted at a previous site (i.e. eagles became “captured,” “marked,” and “recaptured”).

Using these virtual data on matched eagle observations, we developed what are commonly called encounter histories. In brief, encounter histories comprise a sequence of 1s and 0s unique to each eagle. In a given sequence, a 1 represents either the event of first “capture and marking” or a subsequent “recapture” after being previously marked and released back into the wild, and a 0 represents an event when an eagle was not “captured or recaptured” at a previous or subsequent migration monitoring site. For modern CMR approaches, extensions of Lincoln (1930) and Petersen’s (1894) early work, encounter histories are the necessary input data for a statistical model. Because we were interested in estimating eagle abundance in a particular area (i.e. the Kittatinny Ridge) over time, we chose the Population Analysis (POPAN) Jolly-Seber model—the right tool for the job.

Most exciting for us, our methodology worked. We produced population abundance estimates for Golden Eagles migrating along the Kittatinny Ridge each autumn. To boot, two sets of our estimates followed the necessary rules (e.g., statistical model goodness-of-fit tests) for us to consider them reliable by modern CMR standards. Together, our best models estimated that approximately 1,350 Golden Eagles migrated along the Kittatinny Ridge each November, 2002–2011.

In the end, we feel that we have produced a useful framework for evaluating other migratory bird populations based on similar data and known movement behaviors. Our proposed methodology not only builds upon the legacy of modern CMR work, but is also far more cost-effective than physical CMR and other costly survey techniques. In the case of fixed-wing aircraft surveys for Golden Eagles in the western United States alone, our work costs far less than the annual ~$320,000 necessary to implement such surveys. Most importantly, such an achievement was only made possible by the tireless work of numerous dedicated citizen-scientists, whose standardized and centrally managed data can provide wildlife researchers and managers with quality information useful in conservation decisions. To our friends at the Hawk Migration Association of North America, for all of their data collection and management year-in and year-out, our team is abundantly grateful—pun intended!

References

Bailey, N. T. J. 1952. Improvements in the interpretation of recapture data. Journal of Animal Ecology 21:120–127.

Le Cren, E. D. 1965. A note on the history of mark-recapture population estimates. Journal of Animal Ecology 34:453–454.

Lincoln, F. C. 1930. Calculating waterfowl abundance on the basis of banding returns. Circulation of the U.S. Department of Agriculture No. 118.

Petersen, C. G. J. 1894. On the biology of our flat-fishes and on the decrease of our flat-fish fisheries: with some observations showing to remedy the latter and promote the flat-fish fisheries in our seas east of the Skaw. Report of the Danish Biological Station No. IV (1893–94).

How Many Golden Eagles Are There?

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Photo credit: D. Brandes

For conservation efforts to be effective, wildlife managers need to know how many individuals of a species are out there. When species are spread out over large areas and occur at low densities, as is the case with the Golden Eagle, figuring this out can be tricky. However, a new study from The Condor: Ornithological Applications applies an old technique called “mark-recapture” in a novel way, eliminating the need to actually capture and mark eagles but instead, using math that allows scientists to turn individual observations into population estimates.

West Virginia University’s Andrew Dennhardt, Adam Duerr, and Todd Katzner and Lafayette College’s David Brandes used observations made by volunteer “citizen-scientists” of Golden Eagles migrating along a single, long mountain ridgeline in Pennsylvania to estimate the total number of eagles passing through the area each year. To do this, they developed a new way to apply a classic ecology tool called mark-recapture analysis—capturing and marking a portion of a population, and then counting the number of marked individuals in another group captured later. Helped by the fact that observers were often able to categorize individual eagles as either immature or adult birds, the scientists were able to identify instances of individual eagles being sighted at more than one location as they made their way south along the ridge over the course of a day, treating these subsequent sightings as “recaptures.”

Volunteers reported more than 3,000 sightings of Golden Eagles at five count sites along the ridge from 2002 to 2011. The analysis used in the study, which lets researchers estimate how many birds were missed as well as how many were seen more than once, suggests that these sightings represented between 2,592 and 2,775 individual eagles over the ten year period, with approximately 1,300 passing through the area on average in a given year. Past studies indicate that the total population of eagles breeding in Quebec and migrating through Pennsylvania is around 5,000, making this about a quarter of the larger population. Because the eagles are difficult to count on their breeding grounds, however, better methods for tracking their numbers during migration represent a significant advance.

“Conservation of Golden Eagles in eastern North America is a really important goal for lots of reasons—it is a small, historically declining population, at risk from anthropogenic threats and habitat loss. A central part of that conservation goal is figuring out how many of the darn things there are. Andrew’s work is the first empirical estimate of golden eagle population size,” says Katzner, now a Research Wildlife Biologist at the US Geological Survey. “Nothing quite like this has ever been done. We’ve taken a standard tool, mark–recapture, and turned it on its head to give us a new way to estimate population size.”

“For me, this was a dream come true, because I got to work on a project relevant to the conservation of the species that originally inspired me to enter the field of wildlife ecology and management,” says Dennhardt, now at Michigan State University. “Partnerships between researchers and citizen-scientists can help improve wildlife management decisions to address threats to migratory Golden Eagles and other species. I hope this work inspires future researchers to evaluate the populations of other migratory species, and that it encourages the greater scientific community to consider new and existing citizen-science programs and think about how such programs’ data might be used in their own research toward improving resource management and decision making.”

Applying citizen-science data and mark–recapture models to estimate numbers of migrant Golden Eagles in an Important Bird Area in eastern North America is available at http://www.bioone.org/doi/full/10.1650/CONDOR-16-166.1.

About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology. It began in 1899 as the journal of the Cooper Ornithological Club, a group of ornithologists in California that became the Cooper Ornithological Society, which merged with the American Ornithologists’ Union in 2016 to become the American Ornithological Society. In 2016, The Condor had the number one impact factor among 24 ornithology journals.

AUTHOR BLOG: How Canada Warblers Keep Up with the Joneses

Anjolene Hunt

Linked paper: Forestry and conspecifics influence Canada Warbler (Cardellina canadensis) habitat use and reproductive activity in boreal Alberta, Canada by A.R. Hunt, E.M. Bayne, and S. Haché, The Condor: Ornithological Applications 119:4, November 2017.

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Could a behavioral phenomenon, like the tendency of birds to live near neighbors, change the way we think about the effects of habitat disturbance? Results from new paper in The Condor: Ornithological Applications suggest that for Canada Warblers, this may be the case.

These iconic, brightly colored boreal songbirds are declining in number. Habitat loss and degradation are likely the main culprits. While it is true that forestry changes the landscape across much of the Canada Warbler breeding range, it remains contentious whether this results in habitat loss or whether they will use and thrive in regenerating postharvest areas. We suspected this discrepancy in our understanding of forestry effects could be explained by social factors influencing how Canada Warblers choose where to live.

Just as you might choose a neighborhood based on criteria like access to green space, birds also assess their physical environment when choosing where to live. These species-habitat relationships help biologists understand which areas to protect.

But the physical environment is far from the only cue birds use to choose a place to live, nor is it the only cue we use to understand why they live where they do. Just as you might rely on friends’ opinions of a neighborhood to snatch up a good place before it’s off the market, birds may choose to live near members of their own species. If another bird picks an area, chances are it has high quality food, nesting areas, and mates. However, if everybody makes the same decision, problems can arise as they pack into the same location. When habitat is disturbed, choosing to live near neighbors can result in overcrowding in the remaining undisturbed areas and potentially force some birds into the outskirts of high-quality neighborhoods.

After returning from a long spring migration, Canada Warblers have limited time to find a breeding site (they have the shortest breeding season of wood warblers in Alberta!), and strangely, researchers always seem to find Canada Warblers clustered together in some areas while absent from others. Based on this information, we suspected that where Canada Warblers choose to breed might depend on where their neighbors chose to settle. If this is the case, it could explain why they will live in postharvest areas, and in turn, how we perceive the effects of forestry.

Taking quads down muddy trails and bushwhacking through dense shrubbery to our destination, we surveyed for Canada Warblers in boreal Alberta, Canada. We used a recorded song to mimic an intruding male and lure territory owners into our nets. Once captured, we attached color bands to their legs to distinguish between individuals and followed them throughout the breeding season. We documented their space use in and around postharvest areas, how close they were to neighbors, and whether they found a female mate and raised young. See what a day in the life of Canada Warbler biologist looks like here.

Our results showed that numbers of male Canada Warblers were much lower in postharvest areas compared to unharvested forest. The few males that did live partially in postharvest were typically at the edge of nearby unharvested forest. Males were also more likely to live nearer to neighbors rather than spacing out. Hence, Canada Warblers in the boreal forest may not prefer to live in postharvest areas, but may live there as a side effect of trying to be near neighbors in unharvested forest.

But are Canada Warblers reaping the benefits of living near neighbors, or are they feeling the pressure to keep up with the Joneses? We found males living in areas with more neighbors were more likely to be “single” (without a female mate) than males living in areas with fewer neighbors. Overcrowding may lead to increased male-male competition for limited females. These rivalries also mean that males have to spend more time and energy defending their territory, leaving less time and energy to court females.

Our results suggest that protecting large stretches of unharvested forest near sites occupied by Canada Warblers will be important to provide enough habitat and prevent crowding effects. It also goes to show that appearances can be deceiving when it comes to the use of disturbed habitat and that the influence of social behavior should not be underestimated.

Follow Anjolene on Twitter: twitter.com/AnjoleneHunt

AUTHOR BLOG: Geolocator Effects May Have More to Do with Marking Method Than Mass

Henry Streby

Linked paper: Comment on ‘‘Mixed effects of geolocators on reproduction and survival of Cerulean Warblers, a canopy-dwelling, long-distance migrant’’ by H.M. Streby and G.R. Kramer, The Condor: Ornithological Applications 119:4, November 2017.

Author Blog picUnprecedented numbers of species and individual birds have been marked with all sorts of tracking devices in recent years, and those numbers will continue to rise in the future. The data ornithologists are gathering by marking birds with tracking devices are providing a wealth of previously elusive knowledge about all stages of birds’ life cycles. The rapidity with which new tracking studies are being initiated places an ever-growing burden on the USGS Bird Banding Lab (BBL) and other agencies charged with assessing auxiliary marker requests and determining permission to mark birds on a case-by-case basis. In many cases, those agencies have little to no species-specific information on which to base their decisions, either because a species has never been marked before or because those who marked them did not study or did not report marker effects during the course of their research. We as research biologists have an ethical responsibility to objectively assess the potential effects of our research activities on the animals we study for the sake of minimizing harm to the animals and potential bias in our data caused by markers impacting animal behavior or survival.

We applaud the authors of Raybuck et al. (2017) for honoring a request from the BBL to band additional birds as control groups during their geolocator study of Cerulean Warblers. We believe Raybuck et al. conducted their study and published their paper with ethical and admirable intentions and it was not our intention to criticize the integrity of their research. However, their conclusion of an overall geolocator effect on annual survival of Cerulean Warblers was overreaching in light of the modest sample-sizes and the confounding factors of year, site, and marking method. We believe our analysis and interpretation of their apparent annual survival data is more appropriate and clarifies some small but critical shortcomings in their assessment. Of primary concern, the negative geolocator effect on annual survival of Cerulean Warblers was driven by a strong negative effect associated with one marking method in one year, and there was no support for a negative effect of geolocators when they used a different marking method in the second year of their study. This difference was not driven by geolocator mass, because the reduced survival occurred in the year when a lighter geolocator was used.

In our opinion, there are two broad take-home messages from our paper. First, when marking a species for the first time, it is critical to use available knowledge and replicate methods known to work well in closely related species. When the smallest details are considered, there are almost as many methods for deploying a geolocator on a songbird as there are species that have been marked with geolocators. It should not be necessary for each research group to reinvent methods and relearn unfortunate lessons when simple, safe, and effective methods have been developed and made widely available. Second, there is only one control group that is relevant for comparison to a marked group of birds during a geolocator study or any other study of marked birds: a control group identified at the same site(s) during the same period of the same year. Parameters of interest, especially survival, can vary widely among years and populations. It is therefore not appropriate to compare parameters like survival of geolocator-marked birds with those of control birds from any other population or year or even long-term averages from the same population. Just as we have a responsibility to assess the potential effects of our research on the animals we mark, so too do we have a responsibility to design and present those assessments in a statistically rigorous and scientifically appropriate manner. It is then that we achieve our goal of providing accurate information that may be useful to other researchers and those in oversight positions who use this type of information to decide whether continued or new research is permissible.

AUTHOR BLOG: To the Grasshopper Sparrow, the Grass May Be Greener on the Other Side

Emily Williams

Linked paper: Patterns and correlates of within-season breeding dispersal: A common strategy in a declining grassland songbird by E.J. Williams and W.A. Boyle, The Auk: Ornithological Advances 135:1, January 2018.

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SY-GD, or silver-yellow, green-dark blue, is a male fiercely defending his territory on his favored signpost perch. Photo credit: D. Rintoul

Late in the summer of 2013, when Alice Boyle, a new faculty member at Kansas State University, was embarking on studies of grassland birds at the Konza Prairie Biological Station in northeastern Kansas, she noticed something really curious: Individual Grasshopper Sparrows she had color-banded earlier in the season were suddenly popping up in new places, singing their hearts out in locations far from where they were originally captured. Whether this was a weird one-off or a predictable and common behavior of grassland birds, Boyle didn’t know.

I started at Kansas State University as Alice’s first graduate student the next fall. She told me the story of the Grasshopper Sparrows and the strange things they did over the summer. With my fondness for movement ecology and a taste for novelty, I opted to base my master’s thesis on the rogue Grasshopper Sparrows seeking greener pastures.

To rewind a little bit, I should explain why this kind of behavior was surprising. The Grasshopper Sparrow is a small, grassland-obligate migratory songbird that spends its winters along the Gulf Coast and Northern Mexico and travels to the Great Plains to spend its summers. Migration is energetically costly, requiring a lot of time and preparation. Once birds arrive at breeding grounds, they have a relatively short window of time to set up a territory, find a mate, build a nest, raise young, and feed fledglings, and then undergo molt, feed, and prepare for the long journey back to the wintering grounds. All of this has to be accomplished in a span of a few short months. Given the constraints of time, resources, and energy, you’d think that they would stick pretty close to their original territory for the whole breeding season. That is what most migrant birds do, after all. The fact that Grasshopper Sparrows would switch territories, duplicating their efforts of setting up another territory, finding a potential new mate, and trying to nest again—it seems like it wouldn’t be worth it. The fact that Grasshopper Sparrows are indeed doing this—changing territories once, twice, maybe three times, even—makes them apparently unusual compared to their migratory counterparts and begs the question, why go to all that effort?!

Before we could examine why Grasshopper Sparrows move around during the breeding season, we first needed to determine just how common this kind of behavior was. We also wanted to find out the distances over which they traveled, where were the new places they chose to settle, and how frequently they moved locations. Following that initial season in 2013, we set out to answer these questions and looked for this behavior in full force. In the next three seasons of field work, we banded 779 Grasshopper Sparrows, outfitted 19 individuals with radio-transmitters to follow their movements, and searched for color banded birds throughout our study area every week to keep track of territory holders and their whereabouts throughout the season.

What we found, we couldn’t have predicted: Within-season breeding dispersal behavior in Grasshopper Sparrows was way more common than we expected. Depending on which of the different metrics we calculated, between 33% and 75% of males disperse at least once within a single breeding season. The scale of movement between territory locations was also remarkable; one individual moved 9 km between breeding attempts—a movement considered pretty large to a bird that defends an average territory size of 43 meters in diameter! If we had not been systematically looking for this behavior, we might have easily missed it; in many areas, densities of Grasshopper Sparrows remained constant throughout the breeding season, but the identities of territory holders changed, sometimes more than once over the summer.

The fact that these birds are moving around a lot during the breeding season introduces its own list of new questions. Now that we detailed the patterns of this behavior, we could begin to answer the questions of why. Why do they do this? What determines why some leave, and some stay? And what determines where they settle next? Could this be a common strategy of other birds occupying similar habitats?  While trying to determine whether this movement was truly unusual by digging into the literature, I actually found quite a bit of evidence for such movements. While the terminology is not consistent, it seems that within-season breeding dispersal could be more common in grassland birds than elsewhere.

The answers to some of these questions formed the rest of my MS research, and some remain as ones we are still working on. But now that the first piece of the puzzle is in place, the next steps are to explore the evolutionary and ecological causes of within-season breeding dispersal in such an interesting little brown job.

To find out more regarding this Grasshopper Sparrow movement story, visit aliceboyle.net and follow us on social media.

Emily on Twitter: twitter.com/wayfaringwilly

Alice on Twitter: twitter.com/birdfiddler

Youtube channel: youtube.com/channel/UCiQiNb9syQ5F455XielMjDA

Flickr: flickr.com/photos/141805443@N08/

Grassland Sparrows Constantly Searching for a Nicer Home

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A Grasshopper Sparrow with a radio transmitter. Photo credit: E. Williams

Some birds regularly move to new territories between years, depending on factors including habitat quality and the presence of predators, but what about within a single breeding season? Grassland ecosystems are particularly dynamic, continuously shaped by fire and grazing, and a new study from The Auk: Ornithological Advances confirms that one particular grassland bird moves frequently each summer in search of the best territories. For Grasshopper Sparrows, the grass really does look greener on the other side.

Emily Williams and Alice Boyle of Kansas State University captured 647 male Grasshopper Sparrows over the course of three breeding seasons and marked them with identifying color bands, surveying territories weekly to track their movements. The results indicate that about 75% of males changed territories at least once per season, with a third of banded defending new territories at least 100 meters away from where they were originally sighted. Additionally, 9 of 19 birds fitted with radio transmitters established new territories as far as 1200 meters away from their original locations.

“We had many plots where the density remained relatively stable over the entire breeding season, which could appear as if individual birds remained settled in the same areas over time. However, what we found was the complete opposite—individuals were blinking in and out of territories the entire time,” says Williams, who has since moved on to a position at Denali National Park and Preserve. “So while an onlooker could see a male Grasshopper Sparrow singing on a single patch of ironweed for months at a time, the identity of the individual claiming that ironweed as his own could change two or three times in a single summer.” Without careful observations, researchers could completely miss these dynamic movements happening over the course of a season.

This high turnover implies that while some birds might perceive a patch of habitat as no longer suitable, others see the same area as a good place to settle, perhaps because they base decisions on their individual experiences of nest success or failure. High mobility may benefit grassland birds by helping them locate isolated patches of high-quality habitat and colonize newly created or restored habitat, but could also challenge researchers’ ability to accurately track survival over time.

“Many avian ecologists have probably anecdotally noticed within-season shifts in breeding territories, yet this is one of the first attempts to actually quantify this phenomenon. The extent to which territorial turnover occurred and the fairly extensive distances moved by males within a season are intriguing!” says the University of Wyoming’s Anna Chalfoun, an expert on grassland birds who was not involved in the study. “I am left wondering if this behavior is more common than ornithologists have previously acknowledged and what drives proximate shifts in breeding territories. The results certainly have implications for habitat management for territorial birds of concern and for the accuracy of survival and site fidelity analyses.”

Patterns and correlates of within-season breeding dispersal: A common strategy in a declining grassland songbird is available at http://www.bioone.org/doi/full/10.1642/AUK-17-69.1.

About the journal: The Auk: Ornithological Advances is a peer-reviewed, international journal of ornithology that began in 1884 as the official publication of the American Ornithologists’ Union, which merged with the Cooper Ornithological Society in 2016 to become the American Ornithological Society. In 2009, The Auk was honored as one of the 100 most influential journals of biology and medicine over the past 100 years.

Safety, Not Food, Entices Geese to Cities

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Radio transmitter data has revealed the real reason geese hang out in cities. Photo credit: M. Horath

Canada Geese have shifted their winter range northward in recent years by taking advantage of conditions in urban areas—but what specific features of cities make this possible? A new study from The Condor: Ornithological Applications suggests that rather than food, geese are seeking safety, congregating in areas where they can avoid hunters and be buffered from the coldest winter temperatures.

Heath Hagy of the University of Illinois at Urbana–Champaign and his colleagues captured 41 geese in the Greater Chicago Metropolitan Area between 2014 and 2016 and fitted them with radio transmitters to track their movements. While the geese used a remarkable variety of urban habitats, they preferred deep water and rivers over green space such as parks when temperatures dropped enough to tax their ability to maintain their body temperature. For geese that remained within the metropolitan area, winter survival was 100%, but this dropped to 48% for those that emigrated out to forage in surrounding agricultural fields, countering expectations that the proximity of agricultural habitat may be a factor in geese’s winter expansion in the area. Together, these results suggest that sanctuary may be a higher priority for wintering geese than good foraging habitat.

Better understanding how geese use urban habitat in winter may help reduce human–wildlife conflicts such as collisions with airplanes. “The growth of urban areas and northward expansion of row-crop agriculture have changed the way geese migrate. Unfortunately, some of our large cities have become goose sanctuaries, where resident geese and migratory geese congregate during winter to escape hunting pressure,” says Hagy. “Although additional research is needed, our data will be useful to guide goose harassment efforts, which may offset the benefits of remaining inside urban areas during winter and open hunting seasons.”

“This work offers comprehensive insights into the biology and behavior of a large wintering population of Canada geese that inhabits a major metropolitan area in the mid-western U.S. Appropriately grounded in an energetic context, the study thoroughly describes how Canada geese utilize the urban environment under varying weather conditions and demonstrates the survival benefits of urban adaptation,” according to The Ohio State University’s Robert Gates, a wildlife management expert who was not involved in the research. “Findings from this study provide a firm biological grounding for the development and implementation of management actions to alleviate human–Canada goose conflicts in urban areas.”

Survival and habitat selection of Canada Geese during autumn and winter in metropolitan Chicago, USA is available at http://www.bioone.org/doi/abs/10.1650/CONDOR-16-234.1.

About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology. It began in 1899 as the journal of the Cooper Ornithological Club, a group of ornithologists in California that became the Cooper Ornithological Society, which merged with the American Ornithologists’ Union in 2016 to become the American Ornithological Society. The Condor had the top impact factor among ornithology journals for 2016.

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