176 



The Canadian Field-Naturalist 



[Vol. XXXVI 



appearance below Latchford, persisting in con- 

 siderable numbers down stream at least as far as 

 our last river camp below Poigan Rapids. I 

 realize that none of this evidence is strictly con- 

 c'lusive as regards the segregation of the two zones 

 under discussion, but it does point to a very real, 

 though subtle infusion of the Transition. An 

 observer with more time at his command than I 

 had on this trip, should certainly discover further 

 and more minute distinctions between these two 

 interesting and adjoining regions. 



THE MAMMALS 

 Maries pennanii (Erxleben). Fisher. The 

 only clue I have of the occurrence of this species 

 is that of a well-marked trail which I saw at 



Ababika Lake on Sept. 2. The foot impressions 

 were very distinct in the wet sand of the beach 

 and therefore easily deciphered. 



Mustela vison Schreber. Mink. Presence of 

 the mink was noted at all points enumerated below 

 for muskrat. Their trails were particularly 

 common on the mud beaches above Sucker Gut 

 Falls, and along the river which flows into the 

 lake of the same name from a north-westerly 

 direction. The muddy bottom, in parts, ot 

 Sucker Gut Lake is a most prolific breeding 

 ground of the freshwater clam, and all along the 

 shores at intervals we noticed various-sized piles of 

 their empty shells which signified the presence of 

 mink and rat. 



(To be concluded in the January issue) 



NOTES AND OBSERVATIONS 



Notes on a Saskatchewan Muskrat Colony. 

 In August last, two parent muskrats and their 

 four half-grown young went overland into a 

 sedgy pond of about an acre in extent and two 

 feet in depth in the centre. After two days a 

 burrow was obtained in the state of commence- 

 ment. A trench was dug from the deepest part 

 of the pond straight toward the shore with a very 

 slight incline. The width of the trench was 

 fourteen inches and the earth piled at the end of 

 the trench. All weeds were removed from the 

 deepest part of the water for a radius of thirty 

 feet. The trench gradually deepened until at the 

 water line of the pond it was twenty-eight inches 

 in depth and fourteen inches in width. 



In September the main trench was driven a 

 distance of one hundred and seven feet. At the 

 extreme end a large nest the size of a bushel 

 measure was made three feet under the ground 

 under the roots of a willow. This nest was made 

 of soft dry grass and was completed before the 

 first of October. The burrow was raised three 

 inches above water level at the entrance, and the 

 entrance was thirty feet inland from the water 

 line of the pond shore. That is, there was an 

 open drain from the pond edge to the place where 

 the ground closed over the burrow. Where the 

 burrow proper started under the hill the water 

 measured eighteen inches in depth. 



The three-inch air space at the entrance of the 

 burrow gradually increased until there was no 

 water in the burrow at a distance of forty feet 

 from the entrance. The burrow at the highest 

 water mark was fourteen inches high and nine 

 inches wide. The extra height is used in the 

 spring when the ponds are flooded. The colony 

 can use the burrow without being pressed for air 

 even in case of abnormal floods. 



From the first to the twentieth of October four 

 tunnels eight inches in depth were driven above 



the high water level parallel with the main tunnel 

 and branching from it. Digging into these four tun- 

 nels showed that they averaged a length of twelve 

 feet or forty-eight feet in all. These tunnels 

 were packed with tender bulrush roots, sedges, 

 mints, young grass and reeds. The bulk of the 

 store was white and crisp, and very tightly 

 packed. Each of these tunnels was plugged with 

 clay at the junction with the main tunnel to 

 exclude air. Wherever the tunnel tapped a 

 cattle track or other hole the same was tightly 

 plugged and the tunnel continued. The young 

 muskrats aided the parents by carrying earth from 

 the tunnel and also in bringing in the food store. 

 These six small animals must have carried several 

 hundred pounds of earth and food in the last two 

 months. As the pond is very shallow and will 

 freeze to the bottom before Christmas I am going 

 to find out what these creatures will do when the 

 supply fails. Thomas D. Carter. 



Prairie Warbler, Dendroica discolor. ^It 

 would appear from the literature on the Prairie 

 Warbler that this bird is a casual visitor in On- 

 tario. My first record was made during a visit to 

 the southern portion of Georgian Bay, known as 

 Nattawasaga Bay. While walking along the 

 shore (August 1, 1914) I saw four Warblers high 

 up in a pine and on examining them through my 

 glasses I found them to be the Prairie. On 

 revisiting this spot in 1921, from June until 

 September, I had occasion to study these birds. 

 They were localized and followed the shore line 

 for about fifteen miles, never further than two 

 hundred yards inland. This locality was com- 

 posed of a few scattered oak, white and norway 

 pines, numerous ground juniper, a typical jack 

 pine ridge. In June the male could be heard 

 singing his characteristic song. These Warblers 

 next to the Myrtle, are the commonest in this 



