Little rodent, large urge for food: Researchers determine the dietary impacts of invasive mice on the Farallon Islands – Phys.org


Little rodent, big appetite
View of Southeast Farallon Island from West Finish. Credit score: Level Blue Conservation Science

On an island 30 miles off the coast of San Francisco, a hoard of invasive home mice are packing an ecological wallop far bigger than what their small statures would recommend. These are the conclusions of a examine led by LSU Affiliate Professor of Oceanography and Coastal Sciences Michael Polito, together with researchers from Level Blue Conservation Science, San Jose State College and California State College Channel Islands. The examine was printed at present in PeerJ—Life and Surroundings.

The island in query is Southeast Farallon Island, a part of the Farallon Islands Nationwide Wildlife Refuge, house to the most important seabird breeding colony within the contiguous United States and lots of distinctive native species of crops and animals. Home mice usually are not native to the island however have been unintentionally launched throughout the 1800s or early 1900s. Since then, the inhabitants of has grown to about 50,000 house mice inhabiting the island roughly the scale of two soccer fields. The examine discovered that mice eat and/or compete for meals with native species and due to this fact offers help for the proposed plan by the U.S. Fish and Wildlife Service to eradicate mice from all the South Farallon Islands.

The analysis crew recognized how mice affect this island ecosystem by first gaining a greater understanding of mouse abundance and diets.

“Previous to this analysis, there was a scarcity of knowledge on what precisely mice have been consuming on the island and the way their diets modified all year long,” Polito mentioned.






Home mice have been unintentionally launched to the Farallon Islands Nationwide Wildlife Refuge, house to the most important seabird breeding colony within the contiguous US, and the inhabitants has grown to about 50,000 home mice inhabiting the island roughly the scale of two soccer fields. The examine discovered that mice eat and/or compete for meals with native species and due to this fact offers help for the proposed plan by the U.S. Fish and Wildlife Service to eradicate mice from all the South Farallon Islands. Credit score: Level Blue Conservation Science

To check mouse diets, the scientists used a method known as steady isotope evaluation, which traces the distinctive chemical signatures of meals sources into mouse tissues.

“Successfully mice are what they eat,” Polito mentioned.

As well as, Polito and his colleagues examined the seasonal abundance of launched mice over a 17-year interval and associated it to the provision of native seabirds, salamanders, bugs and vegetation on the island.

Little rodent, big appetite
Home mice have been unintentionally launched to the Farallon Islands Nationwide Wildlife Refuge, house to the most important seabird breeding colony within the contiguous US, and the inhabitants has grown to about 50,000 home mice inhabiting the island roughly the scale of two soccer fields. Credit score: Level Blue Conservation Science

They conclude that mice are extremely “omnivorous and opportunistic” eaters whose population numbers and diets differ dramatically all year long in response to adjustments in meals availability and seasonal local weather. The researchers found that within the spring when the mouse inhabitants is low, they eat primarily crops. As summer season rolls round, when their numbers start to extend, the mice begin to dine extra on native bugs and seabirds. Within the fall, when the mouse inhabitants is booming, their diets transition extra totally to bugs, placing them in direct competitors with the Farallon arboreal salamander, a species discovered solely on the islands. Mouse numbers then decline throughout the cooler, wetter circumstances of winter.

Little rodent, big appetite
This examine discovered that mice eat and/or compete for meals with native species such because the endemic Farallon salamander and due to this fact offers help for the proposed plan by the U.S. Fish and Wildlife Service to eradicate mice from all the South Farallon Islands. Credit score: Level Blue Conservation Science

Whereas it stays unclear the diploma to which mice are actively depredating seabirds, or simply scavenging off deserted eggs and carcasses, prior research have discovered that simply the presence of mice on the islands attracts migratory predators, similar to Burrowing owls, which then prey on uncommon native seabirds. The very nature of the island setting itself additionally results in invasive mice having an outsized affect.

“Native crops and lots of animals cannot depart the island to get away from the mice, and these crops and wildlife by no means needed to evolve defensive behaviors in opposition to rodents in the way in which that mainland species have,” Polito mentioned.

Little rodent, big appetite
Evaluation for this examine on the Farallon Islands ecosystem, the most important seabird breeding colony within the contiguous U.S., was performed at Louisiana State College. Credit score: Level Blue Conservation Science

The researchers conclude that mice have wide-ranging influences on the island’s ecosystem as a consequence of their excessive abundance and opportunistic diets.

“Our examine offers the newest and most complete understanding of mouse diet and the impacts they’re having on the native neighborhood—particularly to the endemic arboreal salamander,” mentioned Pete Warzybok, Farallon Islands Program Lead at Level Blue Conservation Science and a co-author of the paper. “These findings make a stronger-than-ever case for the eradication of the mice as a vital step in restoring the Farallon Islands ecosystem.”


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Extra info:
Michael J. Polito et al, Inhabitants dynamics and useful resource availability drive seasonal shifts within the consumptive and aggressive impacts of launched home mice (Mus musculus) on an island ecosystem, PeerJ (2022). DOI: 10.7717/peerj.13904

Journal info:
PeerJ


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Little rodent, large urge for food: Researchers determine the dietary impacts of invasive mice on the Farallon Islands (2022, September 22)
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