Examination of multiple working hypotheses to address reproductive failure in reintroduced Whooping Cranes

Barzen, Jeb A.; Converse, Sarah J.; Adler, Peter H.; Lacy, Anne E.; Gray, Elmer W.; Gossens, Andrew P.

doi:10.1650/condor-17-263.1

Cited by 7 publications

(16 citation statements)

References 39 publications

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“…The average of all S. annulus trapped in 2011 and 2012 was 12% of the average of the total trapped in 2009 and 2013, and for S. johannseni the figure was <1% (calculated from data of Barzen et al. ). Rapid population recovery of black flies after Bti treatments is typical; some programs require up to 15 treatments per site every year (Adler et al.…”

Section: Determining the Role Of Black Flies In Nest Desertionmentioning

confidence: 88%

“…Subsequent monitoring of larval populations of these 2 species (2010–2013) was conducted with standardized methods (Barzen et al. ). Centers for Disease Control (CDC) traps baited with carbon dioxide allowed monitoring of adult flies near crane nests on NNWR to create indices of fly abundance within the nesting season (King & Adler ; Barzen et al.…”

Section: Defining Patterns Of Black Fly Activity and Distributionmentioning

confidence: 99%

“…Sampling of larvae on NNWR itself indicated that larval populations of S. annulus and S. johannseni were small compared with other sampled sites in 2009 and consisted of fewer than 10 individuals annually from 2010 to 2013 (Barzen et al. ).…”

Section: Defining Patterns Of Black Fly Activity and Distributionmentioning

confidence: 99%

“…If black fly suppression was responsible for increased nesting, nest success should also be low in years before (2009) and after (2013) Bti treatments of rivers (Barzen et al. ).…”

Section: Determining the Role Of Black Flies In Nest Desertionmentioning

confidence: 99%

“…Adult black flies were substantially reduced in both years, but in 2013, when no Bti was applied, they rebounded to levels exceeding those of 2009, the pretreatment year (Barzen et al. ). The average of all S. annulus trapped in 2011 and 2012 was 12% of the average of the total trapped in 2009 and 2013, and for S. johannseni the figure was <1% (calculated from data of Barzen et al.…”

Section: Determining the Role Of Black Flies In Nest Desertionmentioning

confidence: 99%

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The dilemma of pest suppression in the conservation of endangered species

Adler

Barzen

Gray

et al. 2019

Conservation Biology

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In the conservation of endangered species, suppression of a population of one native species to benefit another poses challenges. Examples include predator control and nest parasite reduction. Less obvious is the control of blood‐feeding arthropods. We conducted a case study of the effect of native black flies (Simulium spp.) on reintroduced Whooping Cranes (Grus americana). Our intent was to provide a science‐driven approach for determining the effects of blood‐feeding arthropods on endangered vertebrates and identifying optimal management actions for managers faced with competing objectives. A multiyear experiment demonstrated that black flies reduce nest success in cranes by driving incubating birds off their nests. We used a decision‐analytic approach to develop creative management alternatives and evaluate trade‐offs among competing objectives. We identified 4 management objectives: establish a self‐sustaining crane population, improve crane well‐being, maintain native black flies as functional components of the ecosystem, and minimize costs. We next identified potential management alternatives: do nothing, suppress black flies, force crane renesting to occur after the activity period of black flies, relocate releases of cranes, suppress black flies and relocate releases, or force crane renesting and relocate releases. We then developed predictions on constructed scales of 0 (worst‐performing alternative) to 1 (best‐performing alternative) to indicate how alternative actions performed in terms of management objectives. The optimal action depended on the relative importance of each objective to a decision maker. Only relocating releases was a dominated alternative, indicating that it was not optimal regardless of the relative importance of objectives. A rational decision maker could choose any other management alternative we considered. Recognizing that decisions involve trade‐offs that must be weighed by decision makers is crucial to identifying alternatives that best balance multiple management objectives. Given uncertainty about the population dynamics of blood‐feeding arthropods, an adaptive management approach could offer substantial benefits.

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Section: Determining the Role Of Black Flies In Nest Desertionmentioning

confidence: 88%

Section: Defining Patterns Of Black Fly Activity and Distributionmentioning

confidence: 99%

Section: Defining Patterns Of Black Fly Activity and Distributionmentioning

confidence: 99%

“…If black fly suppression was responsible for increased nesting, nest success should also be low in years before (2009) and after (2013) Bti treatments of rivers (Barzen et al. ).…”

Section: Determining the Role Of Black Flies In Nest Desertionmentioning

confidence: 99%

Section: Determining the Role Of Black Flies In Nest Desertionmentioning

confidence: 99%

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The dilemma of pest suppression in the conservation of endangered species

Adler

Barzen

Gray

et al. 2019

Conservation Biology

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Natal dispersal of Whooping Cranes in the reintroduced Eastern Migratory Population

Thompson

Caven²,

Hayes

et al. 2021

Ecology and Evolution

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Natal dispersal is a key demographic process for evaluating the population rate of change, especially for long‐lived, highly mobile species. This process is largely unknown for reintroduced populations of endangered avian species. We evaluated natal dispersal distances (NDD) for male and female Whooping Cranes (Grus americana) introduced into two locations in central Wisconsin (Necedah National Wildlife Refuge, or NNWR, and the Eastern Rectangle, or ER) using a series of demographic, spatial, and life history‐related covariates. Data were analyzed using gamma regression models with a log‐link function and compared using Akaike information criterion corrected for small sample sizes (AICc). Whooping Cranes released in the ER dispersed 261% further than those released into NNWR, dispersal distance increased 4% for each additional nesting pair, decreased about 24% for males as compared to females, increased by 21% for inexperienced pairs, and decreased by 3% for each additional year of age. Natal philopatry, habitat availability or suitability, and competition for breeding territories may be influencing observed patterns of NDD. Whooping Cranes released in the ER may exhibit longer NDD due to fragmented habitat or conspecific attraction to established breeding pairs at NNWR. Additionally, sex‐biased dispersal may be increasing in this population as there are more individuals from different natal sites forming breeding pairs. As the population grows and continues to disperse, the drivers of NDD patterns may change based on individual or population behavior.

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