Download Policy: Content on the Website is provided to you AS IS for your information and personal use only and may not be sold or licensed nor shared on other sites. SlideServe reserves the right to change this policy at anytime. While downloading, If for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
Feeding Habits of Swans
most of the translocated swans return to the original places the following year.
N American Swans
1) Agricultural plants
- High carbohydrates
2) Wetland plants
- Lower carbohydrates than ag. ｐlants
- Some high water & high fiber content
3) Animal matter
- High protein
- Swans eat tubers, seeds, ….
- Foraging swans go to find pondweeds.
(Earnst & Rothe 2004)
- Eelgrass or Wild celery (Vallisneria spp.)
- Widgeon grass (Ruppia spp.)
- Muskgrass or Skunkweed (Chara spp.)
Eelgrass or Wild celery
Muskgrass or Skunkweed
- Management for recreation
- Low enforcement
from <200 (1935) to 2200 (1993) .
(Baskin 1993, Squires & Anderson 1995)
from 200 (1955) to 5300 (1987), 12600 (1999).
(Conover & Kania 1994, USGS Website 2001)
increased since 1940s, Western 50000(1958),
60000 (2005). (Eastern 100000)
(Sherwood 1960, ADFG Website 2005)
USGS Website 2001
Noordhuis et al. 2002.
Mute & Bewick’s swan
(21-34%: Mitchell & Wass 1995)
- Eat a lot.
- Possible to destroy ecosystem in wetlands.
- And compete with other animals.
1) Significant damage to aquatic plants.
2) Conflict with other shorebirds.
Mitchell & Wass 1996.
Slow down the succession of wetlands.
- Black-necked swan might play an important role as a regulator of aquatic plant biomass to cause a delay in ecological succession (Corti & Schlatter 2002).
- 40% of N and 75% of P in a wetland (Post et al 1998).
- Prefer places with
high food densities & low competition.
Swans visit high food density patches at a higher frequency.
Strong negative correlation b/w the number of swan-days and the number of goose- and wigeon-days (reduction in the food supply).
Food supply decrease make smaller flocks and graze at several different sites. (Klaassen et al. 2006).
- aquatic plants waste grains.
Bewick’s swan: max depth is 0.89m, but prefer shallower water like <0.45m.
Nolet et al. 2006
(New Zealand: Mitchell & Wass 1996)
(Noordhuis et al. 2002)
Badzinski et al. 2006.
When different herbivores with similar food requirements live within the same ecosystem, the animal may not compete but form a grazing succession, where the feeding activity of one group improved conditions for other species present (Vesey-Fitzgerald 1960, Jarman & Sinclair 1979, Mddock 1979).
Destroyer or Succession regulator.