Posted by: PMGDD | September 25, 2020

Nature Miramichi – Marsh Sightings

I made a rash identification of a shrew I found lying on a gravel path at Miramichi Marsh recently. Below is yet another installment of Dave Mcleod’s detailed approach to identifications. Inspiring!

Peter

From: David McLeod <mcleodda@nbnet.nb.ca>
Sent: Wednesday, September 23, 2020 3:08 PM
Subject: Re: Marsh Sightings

Hi Peter and Pam,

Excellent photos, Peter! Lincoln’s Sparrow is #152 for the MM. I’ve attached the updated checklist and credited Peter for photographic evidence and Pam for her earlier sight record(s).

I think the shrew is probably the Common or Masked Shrew (Sorex cinereus). This species is common throughout New Brunswick, while the Long-tailed Shrew (Sorex dispar) is quite rare in the province, being reported from only two locations in Albert County in 1978 and 1979 as of 1984. These two and four other reports from Quebec near the U.S. border with Maine at Lac du Portage, are the only Canadian records, and are the most northerly known locations, with the range extending as far south as southern West Virginia and eastern Tennessee. This information is taken from “Land Mammals of New Brunswick” (Dilworth, 1984), and “Handbook of Canadian Mammals 1; Marsupials and Insectivores” (van Zyll de Jong, 1983). Measurements given in the next paragraph are from the latter.

The means or averages of total and tail lengths for 140 and 143 specimens of S. cinereus are 96.6 mm and 39.9 mm respectively, while the same measurements taken from 6 specimens of the much longer tailed S. dispar are 125.5 mm and 57.8 mm respectively, with the tail being almost 50% of the total length. Using the actual 28 mm diameter of the toonie in the photo, I estimated the tail length to be about 1.2 times that, or about 34 mm. Because of the camera angle, the tail is foreshortened, which would make the actual length closer to the given 39.9 mm for cinereus, that is still much shorter than the 57.8 mm tail length of dispar. The Short-tailed Shrew (Blarina brevicauda) is quite common and the largest shrew in the province, but its tail is only about 25% of its total length, being 30.1 mm and 124.5 mm respectively, and so it is definitely not that.

For comparison, I’ve also attached two additional photos of S. cinereus, one taken by Ken at the marsh on June 11, 2016, which looks quite similar to the one you photographed where the tail length is about 40% of the total length (body and tail), and the other by Jim at his Redmondville property in 2012. In Ken’s photo, which was taken at about the same resolution as yours, note the similar brown pelage of the back and sides with lighter grayish underparts. The tail usually has a dark tip that can be seen on the one in your photo. However, on Ken’s specimen, which seems to be in a later state of decay, as evidenced by the presence of two Bluebottle Flies laying eggs on the carcass, the hairs at the tip appear to have fallen off. This photo was also the basis for inclusion on the mammal checklist for the Miramichi Marsh. Although the colour of the individual in Jim’s photo is not as apparent, the actual total (90 mm) and tail (43 mm) lengths are closest to the measurements for cinereus.

Of the six shrew species known to Northumberland County (eight for NB, including Long-tailed and the next closest with respect to the tail to total length ratio, would be the Smoky Shrew (Sorex fumeus) which has an average total length of 110.1 mm and tail length of 44.7 mm. However, the pelage is decidedly a darker gray (smoky) than the browner colouration of the Common or Masked Shrew. For comparison to the one in your photo, I’ve attached a fourth photo of a Smoky Shrew taken by my brother, Robin, on June 28, 2005, that was found dead along the Fish Quarry Trail at French Fort Cove. This identification has since been confirmed by Don McAlpine at the New Brunswick Museum. Also note the small clusters of maggots on the shrew’s belly, an indication that decomposition has already started.

Dave

BIRD CHECKLIST FOR MIRAMICHI MARSH, updated Sept. 19, 2020.doc


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