The Arizona project began with a problem that was easy to see but difficult to solve.
asserted
that → begin → problem
American bullfrogs had established themselves in the Cienega Creek watershed, where they could prey on Chiricahua leopard frogs and carry the fungal disease chytridiomycosis.
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they → establish → disease
The response involved more than removing the invasive frogs.
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response → involve → frogs
Managers also had to keep them from returning, improve water sources and give the threatened leopard frogs places where they could breed and move between populations.
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they → have → populations
According to The Nature Conservancy blog, by 2019, the area used for Chiricahua leopard frog reintroduction had expanded from seven sites covering 42 square kilometres in 2013 to 19 sites across 84 square kilometres.
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area → accord → kilometres
How Cienega Creek conservationists tackled invasive bullfrogs and frog decline
Cienega Creek runs through southeastern Arizona, where mountain drainage meets semidesert grassland and riparian habitat.
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drainage → tackle → grassland
Much of the watershed is protected within the Las Cienegas National Conservation Area and the Cienega Creek Natural Preserve, but protection alone did not remove the pressures facing its amphibians.
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protection → protect → amphibians
The creek supports several species of conservation concern, including the lowland leopard frog, the threatened Chiricahua leopard frog and the endangered Gila chub and Gila topminnow.
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creek → support → frog
Its relatively small and isolated aquatic system also gave conservation managers an advantage.
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system → give → advantage
Unlike larger, connected waterways where invasive species can be difficult to contain, Cienega Creek offered a more manageable setting for attempting bullfrog eradication.
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Creek → connect → eradication
American bullfrogs had arrived in the watershed during the mid-1980s.
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bullfrogs → arrive → mid-1980s
Their presence created a particular problem for Chiricahua leopard frogs.
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presence → create → frogs
Bullfrogs are associated with the disappearance of the native species in other areas, both through predation and through their ability to carry and spread chytrid fungus, a pathogen linked to amphibian declines around the world.
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Bullfrogs → associate → world
Removing the bullfrogs was only the first step
The FROG Conservation Project had worked in the watershed from 2010 to 2013, with the wider partnership continuing under the same name from 2014 through 2019.
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partnership → remove → 2019
Its work combined invasive species control with habitat restoration, monitoring and the establishment of additional leopard frog populations.
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work → combine → populations
Bullfrogs were successfully eradicated from the Cienega Creek complex in 2013.
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Bullfrogs → eradicate → 2013
That did not mean the threat had disappeared.
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threat → mean → ?
A separate population could move in from surrounding areas, so conservationists created a buffer zone extending through Sonoita towards the Mustang Mountains.
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conservationists → move → Mountains
Starting in 2013, University of Arizona scientists checked stock tanks in this area each year and removed bullfrogs when they were found.
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they → start → bullfrogs
Arizona Game and Fish Department biologists joined the monitoring effort in 2015, with help from the US Forest Service and the Appleton-Whittell Research Ranch.
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biologists → join → Service
The removal work itself varied with the habitat and life stage of the frogs.
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work → vary → frogs
US Fish and Wildlife Service reported, teams used draining, dip and seine nets and, for adult bullfrogs in complicated pools, shooting with .22-calibre rifles.
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teams → report → rifles
Fine-mesh hoop traps were useful for catching tadpoles.
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traps → catch → tadpoles
The timing mattered too, with early-season removal of adults and juveniles intended to prevent breeding and dispersal later in the summer.
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removal → matter → summer
Arizona restored ponds to create stronger habitat for leopard frogs
Removing a predator would have meant little if suitable habitat was unavailable.
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habitat → restore → little
Some livestock water infrastructure was enhanced or converted so that it could provide permanent, drought-resistant water for native wildlife as well as working ranches.
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it → enhance → wildlife
The project found that larger ponds tended to hold more frogs, giving their populations greater resilience when conditions changed.
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conditions → find → resilience
Permanent water was important in an arid landscape, while vegetation such as pondweed could provide cover and feeding areas for young leopard frogs.
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vegetation → provide → frogs
Maintained ponds supplied by pumps and wells could also continue providing habitat during dry periods.
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ponds → maintain → periods
The project eventually set out practical recommendations for new leopard frog habitat.
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project → set → habitat
Ponds were advised to be larger than 0.1 acres, retain permanent water and contain plants such as pondweed and spikerush.
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Ponds → advise → pondweed
A deeper central section could provide a refuge when seasonal drying occurred or when pond infrastructure failed.
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infrastructure → provide → refuge
Regular checks were also recommended so managers could keep track of water conditions and frog populations.
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managers → recommend → conditions
The reintroduction network expanded
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network → expand → ?
The changes became visible in the distribution of Chiricahua leopard frogs.
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changes → become → frogs
As reported by US Fish and Wildlife Service, partners raised and released 4,769 frogs at 10 new sites.
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partners → report → sites
In 2013, the reintroduction area contained seven breeding sites covering about 42 square kilometres.
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area → contain → kilometres
By 2019, it had expanded to 19 sites covering 84 square kilometres.
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it → expand → kilometres
The case study does not say that 19 sites were all actively breeding by 2019.
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sites → say → 2019
It reports that Chiricahua leopard frogs were present at 24 sites across the wider management area at that point, including six that were active breeding sites.
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that → report → six
…and 8 more, not listed.
The Aporia
