. The Canadian field-naturalist. 236 The Canadian Field-Naturalist Vol. 89. Figure 1. An adult leech {Theromyzon rude) attached to the conjunctiva beneath the nictitating membrane of this juvenile Lesser Scaup is conspicuous, while another leech is visible through the nare (arrov/s). The leech still clings to the conjunctiva after the nictitating membrane was slipped over its body (inset). Kuznetsova (1955) and Roberts (1955) re- ported that the cornea of waterfowl became opaque after leeches fed at the conjunctiva. Kuznetsova (1955) also observed that some- times the eye increased in size, ev
. The Canadian field-naturalist. 236 The Canadian Field-Naturalist Vol. 89. Figure 1. An adult leech {Theromyzon rude) attached to the conjunctiva beneath the nictitating membrane of this juvenile Lesser Scaup is conspicuous, while another leech is visible through the nare (arrov/s). The leech still clings to the conjunctiva after the nictitating membrane was slipped over its body (inset). Kuznetsova (1955) and Roberts (1955) re- ported that the cornea of waterfowl became opaque after leeches fed at the conjunctiva. Kuznetsova (1955) also observed that some- times the eye increased in size, even to the extent that it came out of the orbit. We did not observe any such signs of eye injury to any ducks handled in this study. Nasal Chamber Leeches attached themselves to the mucosa anywhere within the bird's nasal chamber, but generally posterior from the nares to, and occasionally inside of, the lacrimal ducts (Fig- ure 2). Adult and young leeches that were deep within the nasal chamber were usually detected only after detailed post-mortem examination, but some adult leeches were visible through the nares (Figure 3). Engorged leeches protruding from the nares were swollen on both ends and constricted in the middle where the body passed through the nare. Such leeches were readily observed from a distance with the aid of binoculars or telescopes. Entrance to the nasal chambers by both adult and young leeches is probably gained more frequently through the nares following attachment to and movement from the bill, and less frequently through the buccal cavity and then the pharynx following ingestion. In addition, the young leeches may be trans- ported into the nasal chamber on adults. Ducks react to the apparent discomfort caused by leeches in their nasal chambers by scratching with their feet at leeches protruding. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these i
Size: 1893px × 1319px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorottawafieldnaturalistsclub, bookcentury1900, bookcolle
