Okay, all of these are referenced from other artists here on DA (photographers) (please bear in mind that these are sketches and the actual photographs are AMAZING), so here they are:

Spaniel on lefthand side: "Out of the Darkness" by ladyhawk21 [link]

Lizard on leaf on bottom left: "Shadow" by ladyhawk21 [link]

Flower on lefthand side: "Sweet" by photodream [link]

Weasels on the righthand side are both images from HardpointPhotography [link] and [link]

Kestrel in upper left corner is "Kestrel Portrait" by HardpointPhotography [link]

Cat in the center is "I am cute" by ninazdesign [link]

Cat in the upper right corner is "Miss Moustache" by CroEva [link]

The hummingbird on the top is "Hummingbird_2" by Imaginer2005 [link]

The yawning fox on the bottom right is "Fox 11" by HardpointPhotography [link]

The bird perched on the stick on the upper righthand side is "Tufted Titmouse" by Wessonnative [link]

The horse head on the upper left is from "Kormant" by EquiPhoto [link]

The greyhound on the bottom is from "Come and play with me" by Lachrymose1 [link]

The monkeys on the righthand side and in the upper middle are both from HardpointPhotography [link] and [link]

The mouse in the center left is from "Harvest Mouse" by HardpointPhotography [link]

The falcon toward the bottom left is (poorly) drawn from "Horus" by thrymyeye [link]

The spaniel toward the center right is from "Sniff the still air" by Lachrymose1 [link]

The squirrel standing in the center is from "Thief" by Wessonnative [link]

Last but not least, the lynx in the lower middle is from "Luchs III" by Schoelli [link]