The Sky Islands
The Sky Islands By Chelsea Verstegen
The Madrean Sky Islands; Photo from Livescience.com
History of the sky islands The Madrean Sky Islands harbor one of the most biologically diverse areas of the world. Spanning from the southern region of Arizona across New Mexico and northern Mexico, the Madrean sky islands are distributed across about 42 mountain ranges. The term “sky islands” is used to describe a type of continental terrain consisting of a sequence of valleys and mountains. Both mountain and valley render unique species due to their isolation caused by foreign predators and geographic borders. The diversity of species that is normally seen across hundred of kilometers of latitude occurs over a measly few kilometers in a sky island environment. A total of about 20 sky island complexes exist across the planet and can be found on every continent except Australia. Big Bend is peppered with sky island mountain ranges including the twenty-mile-long Chisos Mountains, and is considered to be one of the most botanically diverse places in North America. Coahuila, a region in Mexico that is also home to sky island terrain, is an extreme example of species insularity typical of oceanic islands, including reduced variety of genus and ecological niche expansion, as well as augmented density of several resident bird species, according to the Encyclopedia of Islands. The 20,000 year old Madrean Sky Islands, considered a stepping stone between the Rocky Mountains and the Sierra Madre Mountains, provide a greater amount of climatic variation and thus more potential for evolutionary differentiation than most other areas where sky islands exist due to the configuration which provides two source areas instead of one. Gila Trout
Gila trout; Photo from New Mexico Game & Fish
The unique overlap of several major biological provinces provides home to a broad group of species in the Madrean sky islands. With nearly opposite climates on either side of the isolated mountains consisting of snowfall, forests and desert environments, creatures both of land and sea reside in the area. One in particular, the Gila trout, has an astounding history of transformation. Previously considered part of the salmon family, the Gila trout has evolved over time due to geographic
forces. Currently, introduced game fish are threatening the species. By way of human interference, however, the Gila trout population remains constant. Each spring after the Gila trout produce offspring, members of the trout recovery team travel to the southwestern corner of New Mexico where they send shockwaves through the water to stun the young and old fish. These fish rise to the surface and are used for captive breeding in a hatchery where water temperatures are carefully regulated and aerated with oxygen. Nate Wiese, the manager and lead scientist for the Mora National Fish Hatchery explained the importance of keeping hatcheries as natural as possible in order to ensure the fish remain wild and therefore have a successful reentry into their natural habitat. Genetic diversity is monitored to better the chances of the Gila trout’s survival and reproduction as well as certifying the ability to adapt to the constantly changing environment. “An integral part of the conservation strategy calls to replicate in the wild the distinct genetic lineages,” said Wiese. Not only are the biologists looking to breed as many Gila trout as possible, but they are doing so while still keeping the health of the trout in mind. “We get them off the couch and on a treadmill,” says Wiese. “They are going to be better suited for real streams. It’s like tough-love for your children.” Gila trout are currently being monitored by the United States Endangered Species Act due to habitat loss, hybridization and genetic introgression with the rainbow trout, according to PLOS. Though the Gila trout are not currently listed as endangered, they are considered at risk, though fishing is allowed. The Southwest Native Trout Conservation initiative is also working to ensure the vigor of the Gila trout species by removing non-native species and improving the local habitat, including an area of Arizona that was damaged in 2011 by the largest wildfire in Arizona history. Ocelot
Ocelot; Photo from felid-tag.org
Ocelots are able to adapt to a wide range of habitat types, and the forests of the Madrean sky islands are perfect for their growth and longevity. However, the ocelot was added to the U.S. Federal Endangered Species Act in 1982, though the species is considered of least concern regardless of its decreasing population. Hunting, trapping and habitat degradation are all contributing factors to the decline in the species. Initiatives for conservation are calling for further protection for these animals. With no particular breeding season, this becomes quite difficult. Isolation of current ocelot populations encourages population growth by physically increasing numbers as well as monitoring reproduction success to ensure population stability. It has only been recently that the ocelots have inhabited the Madrean sky islands, however the population growth of Arizona during the past five years has threatened the ecosystem with development of highways, increased traffic and agriculture. Therefore the largest factor to the decline of the ocelot populations is the continued loss of habitat. Squirrels Conservation
Mt. Graham Red Squirrel; Photo from Arizona Game and Fish Department
Biologists have estimated more than 150,000 invertebrate species and 100 mammal species live in the Arizona portion of the sky islands. Included in these are seven species of tree squirrels, more than anywhere else in North America. Three breeds currently receive legal protection: The Mt. Graham red squirrel is endangered while the Santa Catalina gray squirrel and Chiricahua fox squirrel are both of special concern according to the USDA. Though the lush habitat of the sky islands provide these breeds with room to grow and feed, steps must be taken to ensure the future existence of the species. Initiatives are in order to investigate the ecology of forest animals not native to the sky islands, as well as examining the introduction of the Averts squirrels, and assess the factors that influence the diversity of forest mammals including thinning practices.
Salt River Horses
Salt River Horses; Photo from Salt River Wild Horse Management Group
A recent initiative to round up the Salt River horses, another species that currently considers the Madrean sky islands home, has recently been halted due to public outcry. Concerned citizens believed that the free-roaming horses should be left alone, but wilderness experts say that the horses are actually harming the ecosystem that they currently inhabit. The horses are considered feral, an unnatural part of the ecosystem, and their grazing habits are destroying the homes of a fellow endangered species, the Southwestern willow flycatcher. Sandy Bahr, director of the Grand Canyon chapter of the Sierra Club, explains how the horses are harming the local fish as well. “There’s kind of a cascade effect where the function of the river deteriorates (and) you get more sedimentation that can be bad for fish,” Bahr said. The Sierra Club has called for the Forest Service to conduct an analysis of the environment that the horses currently inhabit and the impact they are having on the area. “We see the National Environmental Policy Act process being an opportunity to learn more about what damage they are causing and what the public-safety concerns are and what the options are for addressing it,” Bahr said.
Bahr has also reassured the public that no harm will come to the animals upon removal, a concern the Salt River Wild Horse Management Group, the organization responsible for stopping the removal, had had. A study conducted by BMC Ecology in 2009 documented the impact of feral horses in California desert and found that the animals do in fact cause harm to surrounding areas, and that the Salt River, being a riparian area, could see more damage than the desert climate. In contrast, the study also found that areas with feral horses saw a more diverse botanical life due to seed distribution. Currently, environmental groups and biologists are working to evaluate if the removal of the species would be beneficial to the fragile area and will take action once determined. Sky Island Conservation Efforts With the contrasting climates, it is no wonder the Sky Islands are extremely fragile. Unfortunately, the most detrimental force against the unique area is human interference. Both habitat loss and fragmentation are taking place at an alarming rate, quickly destroying the beautiful location. Arizona was determined the fastest growing state in the nation in 2007 and still remains in the top 10, according to Forbes. With this knowledge, efforts from several groups including Sky Island Alliance and the Center for Biological Diversity are working together to restore the ecosystem in a changing climate.
http://www.wildlife.state.nm.us/fishing/native-new-mexico-fish/gila-troutrecovery-angling/ http://www.livescience.com/30013-madrean-sky-island-archipelago.html http://www.biologicaldiversity.org/campaigns/sky_islands_conservation/ http://www.iucnredlist.org/details/11509/0 http://www.esciencecentral.org/journals/us-wildlife-management-plan-recoveryof-the-endangered-ocelot-leopardus-pardalis-in-arizona-new-mexico-and-texaspfw.1000109.php?aid=19318 http://www.rickbrusca.com/http___www.rickbrusca.com_index.html/The_Sky_Islan ds.html http://www.wildlife.state.nm.us/hunting/information-by-animal/upland-game/ http://reeis.usda.gov/web/crisprojectpages/0188636-forest-mammal-diversityand-conservation-in-sky-island-forests-relicts-impacts-of-introduced-species-andforest-disturbance.html
https://www.fws.gov/news/blog/index.cfm/2015/5/20/Conservation-GeneticsSteers-Gila-Trout-Management http://www.fs.fed.us/rm/pubs_rm/rm_gtr264/rm_gtr264_006_018.pdf http://www.terrain.org/articles/21/skroch.htm https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3352440/ http://www.hcn.org/issues/45.18/the-long-journey-of-the-gila-trout https://www.fws.gov/southwest/es/arizona/Documents/RecoveryPlans/Gila_Trou t_Recovery_Plan_(Draft_3rd_revised).pdf http://www.tu.org/sites/default/files/2014%20Project%20List_0.pdf http://azgfd.net/artman/publish/NewsMedia/Endangered-Mount-Graham-redsquirrel-population-in-southern-Arizona-decreases.shtml Trout and Salmon of North America by Robert Behnke The Behavior and Ecology of Pacific Salmon and Trout by Thomas P. Quinn Encyclopedia of Islands by Rosemary G. Gillespie Stream habitat Improvement and Native Southwestern Trout by John N. Rinne
The Madrean Sky Islands; Photo from Livescience.com
History of the sky islands The Madrean Sky Islands harbor one of the most biologically diverse areas of the world. Spanning from the southern region of Arizona across New Mexico and northern Mexico, the Madrean sky islands are distributed across about 42 mountain ranges. The term “sky islands” is used to describe a type of continental terrain consisting of a sequence of valleys and mountains. Both mountain and valley render unique species due to their isolation caused by foreign predators and geographic borders. The diversity of species that is normally seen across hundred of kilometers of latitude occurs over a measly few kilometers in a sky island environment. A total of about 20 sky island complexes exist across the planet and can be found on every continent except Australia. Big Bend is peppered with sky island mountain ranges including the twenty-mile-long Chisos Mountains, and is considered to be one of the most botanically diverse places in North America. Coahuila, a region in Mexico that is also home to sky island terrain, is an extreme example of species insularity typical of oceanic islands, including reduced variety of genus and ecological niche expansion, as well as augmented density of several resident bird species, according to the Encyclopedia of Islands. The 20,000 year old Madrean Sky Islands, considered a stepping stone between the Rocky Mountains and the Sierra Madre Mountains, provide a greater amount of climatic variation and thus more potential for evolutionary differentiation than most other areas where sky islands exist due to the configuration which provides two source areas instead of one. Gila Trout
Gila trout; Photo from New Mexico Game & Fish
The unique overlap of several major biological provinces provides home to a broad group of species in the Madrean sky islands. With nearly opposite climates on either side of the isolated mountains consisting of snowfall, forests and desert environments, creatures both of land and sea reside in the area. One in particular, the Gila trout, has an astounding history of transformation. Previously considered part of the salmon family, the Gila trout has evolved over time due to geographic
forces. Currently, introduced game fish are threatening the species. By way of human interference, however, the Gila trout population remains constant. Each spring after the Gila trout produce offspring, members of the trout recovery team travel to the southwestern corner of New Mexico where they send shockwaves through the water to stun the young and old fish. These fish rise to the surface and are used for captive breeding in a hatchery where water temperatures are carefully regulated and aerated with oxygen. Nate Wiese, the manager and lead scientist for the Mora National Fish Hatchery explained the importance of keeping hatcheries as natural as possible in order to ensure the fish remain wild and therefore have a successful reentry into their natural habitat. Genetic diversity is monitored to better the chances of the Gila trout’s survival and reproduction as well as certifying the ability to adapt to the constantly changing environment. “An integral part of the conservation strategy calls to replicate in the wild the distinct genetic lineages,” said Wiese. Not only are the biologists looking to breed as many Gila trout as possible, but they are doing so while still keeping the health of the trout in mind. “We get them off the couch and on a treadmill,” says Wiese. “They are going to be better suited for real streams. It’s like tough-love for your children.” Gila trout are currently being monitored by the United States Endangered Species Act due to habitat loss, hybridization and genetic introgression with the rainbow trout, according to PLOS. Though the Gila trout are not currently listed as endangered, they are considered at risk, though fishing is allowed. The Southwest Native Trout Conservation initiative is also working to ensure the vigor of the Gila trout species by removing non-native species and improving the local habitat, including an area of Arizona that was damaged in 2011 by the largest wildfire in Arizona history. Ocelot
Ocelot; Photo from felid-tag.org
Ocelots are able to adapt to a wide range of habitat types, and the forests of the Madrean sky islands are perfect for their growth and longevity. However, the ocelot was added to the U.S. Federal Endangered Species Act in 1982, though the species is considered of least concern regardless of its decreasing population. Hunting, trapping and habitat degradation are all contributing factors to the decline in the species. Initiatives for conservation are calling for further protection for these animals. With no particular breeding season, this becomes quite difficult. Isolation of current ocelot populations encourages population growth by physically increasing numbers as well as monitoring reproduction success to ensure population stability. It has only been recently that the ocelots have inhabited the Madrean sky islands, however the population growth of Arizona during the past five years has threatened the ecosystem with development of highways, increased traffic and agriculture. Therefore the largest factor to the decline of the ocelot populations is the continued loss of habitat. Squirrels Conservation
Mt. Graham Red Squirrel; Photo from Arizona Game and Fish Department
Biologists have estimated more than 150,000 invertebrate species and 100 mammal species live in the Arizona portion of the sky islands. Included in these are seven species of tree squirrels, more than anywhere else in North America. Three breeds currently receive legal protection: The Mt. Graham red squirrel is endangered while the Santa Catalina gray squirrel and Chiricahua fox squirrel are both of special concern according to the USDA. Though the lush habitat of the sky islands provide these breeds with room to grow and feed, steps must be taken to ensure the future existence of the species. Initiatives are in order to investigate the ecology of forest animals not native to the sky islands, as well as examining the introduction of the Averts squirrels, and assess the factors that influence the diversity of forest mammals including thinning practices.
Salt River Horses
Salt River Horses; Photo from Salt River Wild Horse Management Group
A recent initiative to round up the Salt River horses, another species that currently considers the Madrean sky islands home, has recently been halted due to public outcry. Concerned citizens believed that the free-roaming horses should be left alone, but wilderness experts say that the horses are actually harming the ecosystem that they currently inhabit. The horses are considered feral, an unnatural part of the ecosystem, and their grazing habits are destroying the homes of a fellow endangered species, the Southwestern willow flycatcher. Sandy Bahr, director of the Grand Canyon chapter of the Sierra Club, explains how the horses are harming the local fish as well. “There’s kind of a cascade effect where the function of the river deteriorates (and) you get more sedimentation that can be bad for fish,” Bahr said. The Sierra Club has called for the Forest Service to conduct an analysis of the environment that the horses currently inhabit and the impact they are having on the area. “We see the National Environmental Policy Act process being an opportunity to learn more about what damage they are causing and what the public-safety concerns are and what the options are for addressing it,” Bahr said.
Bahr has also reassured the public that no harm will come to the animals upon removal, a concern the Salt River Wild Horse Management Group, the organization responsible for stopping the removal, had had. A study conducted by BMC Ecology in 2009 documented the impact of feral horses in California desert and found that the animals do in fact cause harm to surrounding areas, and that the Salt River, being a riparian area, could see more damage than the desert climate. In contrast, the study also found that areas with feral horses saw a more diverse botanical life due to seed distribution. Currently, environmental groups and biologists are working to evaluate if the removal of the species would be beneficial to the fragile area and will take action once determined. Sky Island Conservation Efforts With the contrasting climates, it is no wonder the Sky Islands are extremely fragile. Unfortunately, the most detrimental force against the unique area is human interference. Both habitat loss and fragmentation are taking place at an alarming rate, quickly destroying the beautiful location. Arizona was determined the fastest growing state in the nation in 2007 and still remains in the top 10, according to Forbes. With this knowledge, efforts from several groups including Sky Island Alliance and the Center for Biological Diversity are working together to restore the ecosystem in a changing climate.
http://www.wildlife.state.nm.us/fishing/native-new-mexico-fish/gila-troutrecovery-angling/ http://www.livescience.com/30013-madrean-sky-island-archipelago.html http://www.biologicaldiversity.org/campaigns/sky_islands_conservation/ http://www.iucnredlist.org/details/11509/0 http://www.esciencecentral.org/journals/us-wildlife-management-plan-recoveryof-the-endangered-ocelot-leopardus-pardalis-in-arizona-new-mexico-and-texaspfw.1000109.php?aid=19318 http://www.rickbrusca.com/http___www.rickbrusca.com_index.html/The_Sky_Islan ds.html http://www.wildlife.state.nm.us/hunting/information-by-animal/upland-game/ http://reeis.usda.gov/web/crisprojectpages/0188636-forest-mammal-diversityand-conservation-in-sky-island-forests-relicts-impacts-of-introduced-species-andforest-disturbance.html
https://www.fws.gov/news/blog/index.cfm/2015/5/20/Conservation-GeneticsSteers-Gila-Trout-Management http://www.fs.fed.us/rm/pubs_rm/rm_gtr264/rm_gtr264_006_018.pdf http://www.terrain.org/articles/21/skroch.htm https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3352440/ http://www.hcn.org/issues/45.18/the-long-journey-of-the-gila-trout https://www.fws.gov/southwest/es/arizona/Documents/RecoveryPlans/Gila_Trou t_Recovery_Plan_(Draft_3rd_revised).pdf http://www.tu.org/sites/default/files/2014%20Project%20List_0.pdf http://azgfd.net/artman/publish/NewsMedia/Endangered-Mount-Graham-redsquirrel-population-in-southern-Arizona-decreases.shtml Trout and Salmon of North America by Robert Behnke The Behavior and Ecology of Pacific Salmon and Trout by Thomas P. Quinn Encyclopedia of Islands by Rosemary G. Gillespie Stream habitat Improvement and Native Southwestern Trout by John N. Rinne
