(Miller, 1896).

1856 - July: Specimens collected by Dr. T. M. Brewer
In July of 1856 six specimens were collected from Muskeget Island by Dr. T. M. Brewer (Lyon & Osgood, 1909). This is the earliest report I could find of Microtus breweri and seems to be the first documented occurrence of this species.

1857: First description of Microtus breweri
In 1857 was described by Spencer Fullerton Baird as "Gray Mouse (Arvicola breweri)" on page 525 of volume 8 of Reports of explorations and surveys, to ascertain the most practicable and economical route for a railroad from the Mississippi River to the Pacific Ocean. (Department., U. S. W., 1857). There are several resources online that list the original description of this species as being from 1858, but I can find nothing that supports this, and the original description is clearly dated as 1857.

~1885-1888: The Muskeget Life Saving Station burns
It's very unclear when the fire in the Muskeget Life Saving Station happened but from what I can find it should be anywhere from 1885 to 1888, give or take. The fire happened "a few years before" 1890-1891 (Miller, 1896). This is said to be the cause of the introduction of cats to Muskeget. Supposedly this fire allowed them to escape onto the island and decimate the population of M. breweri. A few secondary sources seem to claim that the fire happened in 1894 but this doesn't line up with Miller (1896).

1887- June 1890: South Point Island
At some point between 1887 and June 1890, South Point was disconnected from Muskeget Island to form South Point Island due to the shifting sands and ocean currents. South Point went from the shape of the dotted lines in the image at the top of this page to the island labeled as "SOUTH PT ID." When the US coastguard surveyed Muskeget in 1887 South Point was still connected to Muskeget. We know that South Point Island was no longer connected by June 25th of 1890 due to a letter written from F. H. Kennard to Gerrit S. Miller describing his and Dr. C. S. Francis' visit to Muskeget from June 25th-29th of 1890. In this letter, Kennard refers to South Point as "South Point Id." and Muskeget as "Muskeget proper." A population of M. breweri remained on South Point and Adams Islands, but were apparently never present on Gravelly Island (Miller, 1896).

Jun 25-29, 1890: The "last" sighting
On June 25th-29th F. H. Kennard and Dr. C. S. Francis visited Muskeget Island and reported seeing M. breweri on the island. "While we saw numbers of them on South Point Id., we did see a very few in the middle of Muskeget... We noticed and marked the difference in the number of mice on South Point Island and on Muskeget and laid it to the cats," (Miller, 1896).

Jun 30, 1890-1891: Extirpation from Muskeget Proper
John R. Sandsbury, the island caretaker at the time, reported that M. breweri disappeared from Muskeget Island some time from 1890-1891. The sighting from June 1890 was the last reported sighting of the species on Muskeget proper at this time (Miller, 1896).

Jul, 1892: M. breweri confirmed to be absent from Muskeget Island
In July of 1892 a careful search of Muskeget was conducted and no trace of M. breweri was found on the island. At the same time, South Point and Adams Islands were reported to have thriving colonies of this species (Miller, 1896).

Dec 28, 1892: Declining on Adams Island
On December 28th, 1892 Miller visited the islands and reported that M. breweri was "...as numerous as before on South Point Island, but the colony on Adams Island had greatly diminished," (Miller, 1896).

Jun 21, 1893: Extirpation from Adams Island and re-introduction to Muskeget proper
In June of 1893 Gerrit S. Miller, Outram Bangs, and Chas F. Batchelder visited Muskeget. "We found that the Microtus colony on Adams Island had entirely disappeared. On South Point Island, however, the mice were so abundant that in less than two hours we caught forty-three. After selecting as many as we wanted for specimens, we turned out twenty-six on Muskeget," (Miller, 1896). At some point prior to the re-introduction of M. breweri to Muskeget, cats were extirpated from the island. I'm not able to find a date for this.
"Of the forty-three taken on June 21, 1893, no less than nineteen were slightly albinistic. Each of these abnormal individuals showed a distinct white patch or tuft on the median line of the head just back of the eyes. Only one specimen was marked with white elsewhere on the body. In this case was a broad white stripe beginning on the lower lip and passing back under the chin and throat. It is a significant fact that in every instance the abnormal color marks were in the median line, and moreover that they occupied regions which in many mammals are normally marked with white," (Miller, 1896).

Jul, 1895: Extirpation from South Point Island and increasing population on Muskeget Island
"... Mr. W. K. Fisher collected two dozen specimens for the U. S. Department of Agriculture during July, 1895. Mr. Fisher found two colonies - both in clumps of beach plum bushes - one at the east end of the island, near the place where we liberated the mice in 1893, the other about a mile farther west. He also found that the species was extinct on South Point Island," (Miller, 1896).

Present Day
Nowadays the Muskeget Vole sits alone on Muskeget Island. South Point, Adams, and Gravelly Islands no longer exist. Thankfully the shifting tides that washed away these islands were the very reason that M. breweri was saved from extinction in the first place. Apparently many individuals on Muskeget still show a white blaze on their forehead, though I can't find evidence for this at the moment. If these individuals do exist though, they're an incredible reminder of this species' long and complicated history on an ever-changing island.

Literature Cited:

Department., U. S. W., Baird, Spencer Fullerton, Baird, Spencer Fullerton, Henry, Joseph, Ford, Thomas H., of Engineers., U. S. A. C., … T. Sinclair’s Lith. (1857). Reports of explorations and surveys, to ascertain the most practicable and economical route for a railroad from the Mississippi River to the Pacific Ocean (σ. 906). Ανακτήθηκε από https://www.biodiversitylibrary.org/item/268867

Lyon, M. W. Jr., & Osgood, W. H. (1909). Catalogue of The Type-Specimens of Mammals in The United States National Museum, Including The Biological Survey Collection. Smithsonian Institution United States National Museum, 62, 82. https://books.google.com/books?id=1B1zo-e7bqoC&lpg=PA82&dq=dr%20t.%20m.%20brewer%20arvicola%20breweri&pg=PP1#v=onepage&q&f=false

Miller, G. S. Jr., (1896). The Beach Mouse of Muskeget Island. Proceedings Of The Boston Society Of Natural History, 27, 75-87. https://books.google.com/books?id=WbYrAAAAYAAJ&ots=KLdJj2Q0XE&lr&pg=PA73#v=onepage&q&f=false

Posted on March 24, 2022 05:52 PM by liliumtbn