Mitigating impacts of invasive alien predators on an endangered sea duck amidst high native predation pressure

Body and organ dynamics, during remigial moult, have been mainly explored on geese, dabbling ducks, and foot-propelled diving ducks, but weakly on sea ducks. This study investigated the internal changes in a wing–foot-propelled sea duck to determine the adaptive strategies implemented. Forty-five male Common Eiders (Atlantic) (Somateria mollissima dresseri Sharpe, 1871), collected in the Gulf of St. Lawrence, were dissected; their body mass, muscle mass, and organ sizes were measured. We tested three hypotheses: (1) S. m. dresseri use a strategic reduction of body mass to reduce the flightlessness duration; (2) organs will exhibit changes consistent with a trade-off between function and maintenance to save and reallocate energy and proteins to feather growth; (3) S. m. dresseri would show lower flight muscle reduction than foot-propelled diving ducks. Somateria mollissima dresseri did not lose body mass, which does not support the first hypothesis. Atrophy of the heart followed by hypertrophy and opposite changes in leg muscle mass and gizzard mass are consistent with the second hypothesis. Flight muscle mass showed lower variations than in other ducks, validating the third hypothesis. We also suggest that the lipid depletion observed early in the moult could be a strategy to reduce foraging effort and minimize the risk of damaging the growing feathers.

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Postautotomy tail movement differs between colour morphs of the red-backed salamander (Plethodon cinereus)

Amphibia-Reptilia ◽

10.1163/15685381-00003107 ◽

2017 ◽

Vol 38 (3) ◽

pp. 395-399 ◽

Cited By ~ 2

Author(s):

Banan W. Otaibi ◽

Quincey K. Johnson ◽

Bradley J. Cosentino

Keyword(s):

Natural Selection ◽

Genetic Correlation ◽

Behavioural Response ◽

Plethodon Cinereus ◽

Predation Pressure ◽

Tail Autotomy ◽

Tail Movement ◽

Colour Morphs ◽

Defensive Mechanism

Striped and unstriped colour morphs of the eastern red-backed salamander,Plethodon cinereus, vary in their pre-attack behavioural response to predators, but it is unknown whether the morphs vary in post-attack strategies. Both morphs employ tail autotomy, a post-attack defensive mechanism enabling an individual to release a portion of their tail to facilitate escape from predation. Postautotomy tail movement diverts attention of a predator away from the individual’s body, so natural selection should favor vigorous tail movement in both colour morphs ofP. cinereus. We compared the degree of postautotomy tail movement between morphs following simulated predation. Striped individuals exhibited substantially longer and faster tail movement than unstriped individuals. Divergence in postautotomy tail movement may be a direct evolved response to variable predation pressure between colour morphs. Alternatively, tail movement may be constrained in the unstriped morph due to a genetic correlation with colouration (e.g., pleiotropy).

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Vigilance and foraging patterns of American elk during the rut in habitats with and without predators

Canadian Journal of Zoology ◽

10.1139/z03-011 ◽

2003 ◽

Vol 81 (2) ◽

pp. 266-271 ◽

Cited By ~ 78

Author(s):

Jerry O Wolff ◽

Toni Van Horn

Keyword(s):

Cervus Elaphus ◽

National Park ◽

Forest Cover ◽

Hot Springs ◽

Rocky Mountain ◽

Predation Pressure ◽

Risk Avoidance ◽

Foraging Patterns ◽

Survival And Reproduction ◽

Free Environment

Animal behavior is often optimized as a trade-off between survival and reproduction. During the breeding season, mammals tend to maximize their reproductive effort within the constraints of predation pressure. When predation pressure is reduced, greater effort can be allocated to reproductive behavior and less to vigilance and predator avoidance. The objective of this study was to test the hypothesis that elk, Cervus elaphus, in Yellowstone National Park (YNP), with predators, would spend more time in vigilance and risk-avoidance behavior than would elk in Rocky Mountain National Park (RMNP), a predator-free environment. We further predicted that elk at Mammoth Hot Springs (MAM) in YNP would behave similarly to those at RMNP because predators were absent in that area of the park. Cow elk in YNP spent more time in vigilance and less in foraging during activity periods than did cows in RMNP or MAM. Also, elk in YNP retreated to forest cover during the midday inactive period, whereas elk in RMNP and MAM remained in open habitat. Vigilance was not correlated with group size at either site. Cows with calves spent more time in vigilance and less in foraging than did cows without calves in RMNP and YNP. Bull elk spent most of their time in courtship at all sites, but foraged more at RMNP than in YNP or MAM. Mean harem sizes were similar among the three sites: 17.0 in RMNP, 15.7 in YNP, and 19.0 in MAM. The proportion of cows with calves was significantly lower in the area with predators, YNP (0.10), than in the predator-free areas (0.24 in RMNP and 0.37 in MAM), probably because of greater calf mortality in YNP. Elk in YNP behaved in accordance with a predation risk, whereas those in RMNP and MAM showed less vigilance behavior.

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Beak marks on the wings of butterflies and predation pressure in the field

Entomological Science ◽

10.1111/ens.12076 ◽

2014 ◽

Vol 17 (4) ◽

pp. 371-375 ◽

Cited By ~ 5

Author(s):

Masato Ota ◽

Masahide Yuma ◽

Yoshito Mitsuo ◽

Yuki Togo

Keyword(s):

Predation Pressure

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