{"id":14067,"date":"2018-01-02T09:43:36","date_gmt":"2018-01-02T09:43:36","guid":{"rendered":"https:\/\/www.revoscience.com\/en\/?p=14067"},"modified":"2020-05-27T06:18:06","modified_gmt":"2020-05-27T06:18:06","slug":"decades-past-logging-still-threatens-spotted-owls-national-forests","status":"publish","type":"post","link":"https:\/\/www.revoscience.com\/en\/decades-past-logging-still-threatens-spotted-owls-national-forests\/","title":{"rendered":"Decades-past logging still threatens spotted owls in national forests"},"content":{"rendered":"
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While California spotted owls (left, adult; right, juvenile) typically perch and roost in smaller trees like this incense cedar, their nest trees are often several feet in diameter. PHOTO: DANNY HOFSTADTER<\/figcaption><\/figure>\n

Logging of the largest trees in the Sierra Nevada\u2019s national forests ended in the early 1990s after agreements were struck to protect species\u2019 habitat.<\/span><\/p>\n

But new research reported Dec. 6 in the journal\u00a0Diversity and Distributions<\/a>\u00a0by University of Wisconsin\u2013Madison ecologists shows that spotted owls, one of the iconic species logging restrictions were meant to protect, have continued to experience population declines in the forests.<\/span><\/p>\n

Department of Forest and Wildlife Ecology graduate student\u00a0Gavin Jones<\/a>, Professor\u00a0Zach Peery<\/a>, senior scientist R. J. Guti\u00e9rrez, and their colleagues say the owls in the area may still be paying an \u201cextinction debt\u201d that was created by historical logging of large trees. These large, old trees the owls rely on are slow to grow back, meaning the owl population could still be showing the effects of logging that ended decades ago.<\/span><\/p>\n

Compared to nearby national parks, which were never extensively harvested, national forests in the area were more extensively logged until the 1992 restrictions on harvesting large trees and logging near owl habitat took effect. The new study shows that spotted owl populations are stable in national parks. But in the more recently logged national forests, the researchers suggest historical logging of the largest trees may be contributing to the continued declines in owl populations they observed.<\/span><\/p>\n

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Researchers in Zach Peery\u2019s lab track spotted owl movements using mini-GPS tags fastened to a backpack harness system. Here, Gavin Jones checks the fit of a newly mounted tag. PHOTO: SHEILA WHITMORE<\/figcaption><\/figure>\n

Diagnosing causes of decline is difficult, says Peery, and factors responsible for owl declines are likely complex. \u201cOther factors we didn\u2019t measure could have contributed to declines too, including contamination of owl prey from rodenticides used as part of illegal marijuana cultivation,\u201d he adds, which has been recently observed in other species in the region like the Pacific fisher, a weasel relative. However, the researchers say owl declines were consistent with observations expected in forests with a deficit of large trees.<\/span><\/p>\n

The findings could indicate parallels among other species and other habitats around the world. The results also have the potential to inform policy decisions about how to continue protecting sensitive habitats, since existing regulations may require more time to pay off in bolstering species\u2019 populations.<\/span><\/p>\n

\u201cThe spotted owls\u2019 habitat contains the most economically valuable trees,\u201d says Jones, who is the lead author of the new study. He explains that the ideal spotted owl habitat includes trees that could be more than 6 feet wide and hundreds of feet tall. These giants are often centuries old.<\/span><\/p>\n

Combined with the owls\u2019 long lifespan, the slow regrowth of very large trees means that population declines caused by habitat loss may both take time to appear and last long after protections are put in place. That lag between cause and effect is termed an \u201cextinction debt.\u201d<\/span><\/p>\n

To determine whether spotted owls were paying off this debt, Peery\u2019s group traveled to four sites that included three national forests \u2014 which had been logged \u2014 and two national parks, Kings Canyon and Sequoia, which were left intact. Beginning in 1993, after logging restrictions were established, they surveyed the number of owls each season. That requires a bit of performance from the researchers.<\/span><\/p>\n

\u201cWe wander through the woods at night hooting to ourselves,\u201d Jones says of the surveys they conduct, which attract owls with vocalizations. They can then band individual owls they encounter to track them from season to season. Jones was only 4 years old when the surveys began. \u201cI\u2019m the beneficiary of decades of work,\u201d he says. They also used satellite information to determine the area covered by trees and relied on a new set of data on the size of trees recorded by other scientists.<\/span><\/p>\n

While the habitat was stable in the once-logged national forests as a result of habitat retention guidelines implemented by the U.S. Forest Service, these areas are characterized by a large-tree deficit. Jones and his colleagues found that the owl populations in these areas had continued to decline \u2014 evidence of an extinction debt. In contrast, the nearby national parks hosted stable owl populations, even though their habitat wasn\u2019t actively improving. High-quality owl habitat was about four times more common within owl sites in the national parks as in the national forests.<\/span><\/p>\n

\u201cThere is a shortage of very large, old trees that support spotted owls that take decades to centuries to regenerate,\u201d explains Jones. \u201cOwl populations could stabilize in their forests with a large-tree deficit, but it will take time to regrow the trees they rely on.\u201d He says spotted owls aren\u2019t unique in their plight. \u201cAny species can continue to experience decline after you remove habitat,\u201d he says.<\/span><\/p>\n

The takeaway, says Jones, is that stabilizing, and even increasing, spotted owl populations might require more than just halting habitat loss. It likely requires restoring the large, ancient trees they rely on to the landscape \u2014 and patience.<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

Logging of the largest trees in the Sierra Nevada\u2019s national forests ended in the early 1990s after agreements were struck to protect species\u2019 habitat. But new research reported Dec. 6 in the journal\u00a0Diversity and Distributions\u00a0by University of Wisconsin\u2013Madison ecologists shows that spotted owls, one of the iconic species logging restrictions were meant to protect, have […]<\/p>\n","protected":false},"author":6,"featured_media":14068,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[15,17],"tags":[],"class_list":["post-14067","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-environment","category-research"],"featured_image_urls":{"full":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/01\/adult_and_juvi-775x517.jpg",775,517,false],"thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/01\/adult_and_juvi-775x517-150x150.jpg",150,150,true],"medium":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/01\/adult_and_juvi-775x517-300x200.jpg",300,200,true],"medium_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/01\/adult_and_juvi-775x517-768x512.jpg",750,500,true],"large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/01\/adult_and_juvi-775x517.jpg",750,500,false],"1536x1536":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/01\/adult_and_juvi-775x517.jpg",775,517,false],"2048x2048":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/01\/adult_and_juvi-775x517.jpg",775,517,false],"ultp_layout_landscape_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/01\/adult_and_juvi-775x517.jpg",775,517,false],"ultp_layout_landscape":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/01\/adult_and_juvi-775x517.jpg",775,517,false],"ultp_layout_portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/01\/adult_and_juvi-775x517.jpg",600,400,false],"ultp_layout_square":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/01\/adult_and_juvi-775x517.jpg",600,400,false],"newspaper-x-single-post":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/01\/adult_and_juvi-775x517.jpg",735,490,false],"newspaper-x-recent-post-big":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/01\/adult_and_juvi-775x517.jpg",540,360,false],"newspaper-x-recent-post-list-image":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/01\/adult_and_juvi-775x517.jpg",95,63,false],"web-stories-poster-portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/01\/adult_and_juvi-775x517.jpg",640,427,false],"web-stories-publisher-logo":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/01\/adult_and_juvi-775x517.jpg",96,64,false],"web-stories-thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/01\/adult_and_juvi-775x517.jpg",150,100,false]},"author_info":{"info":["Amrita Tuladhar"]},"category_info":"Environment<\/a> Research<\/a>","tag_info":"Research","comment_count":"0","_links":{"self":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/14067","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/comments?post=14067"}],"version-history":[{"count":0,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/14067\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media\/14068"}],"wp:attachment":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media?parent=14067"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/categories?post=14067"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/tags?post=14067"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}