Browsing All Posts filed under »behaviour«

How fish negotiate culverts

March 27, 2017

0

While culverts are designed to facilitate the movement of water by allowing it to flow under roads or other obstructions, they can place physiological and/or behavioural restrictions on the movements of fish. Although several studies have considered the implications of culvert design for fish passage, surprisingly few have tried to identify the factors that influence […]

How fishing changes catchability

March 27, 2017

0

The bolder members of a fish population – often defined as those most willing to continue to forage under the threat of predation – tend to be relatively exploratory, aggressive, territorial, and enjoy higher rates of food intake and specific growth than more timid individuals. However, their larger size makes bold fish more vulnerable to […]

Water birds bring up the subject of plant dispersal

December 13, 2016

Comments Off on Water birds bring up the subject of plant dispersal

Waterfowl play an important role in the dispersal of plants by consuming and then defaecating their seeds. However, although birds such as ducks ingest a wide range of seeds, the digestive activity in their guts generally means that soft-bodied seeds become non-viable. Regurgitation of still-intact seeds is a possible alternative method of dispersal that allows […]

Predators concentrate on current-concentrated prey

December 13, 2016

Comments Off on Predators concentrate on current-concentrated prey

In marine environments, recirculating eddies, upwellings and downwellings play an important role in concentrating plankton in small areas, a process that attracts predators such as fish, mammals and birds and boosts ecological productivity significantly above background levels. However, much less is known about the ways in which physical processes may concentrate organisms and intensify food-web […]

The dynamics of habitat choice: alien predators stifle amphibian breeding

June 1, 2016

Comments Off on The dynamics of habitat choice: alien predators stifle amphibian breeding

The way that animals select habitats reflects their need to balance the costs and benefits associated with factors such as food availability and predation risk. Therefore, habitat choices should vary in response to changes in these key factors. As an example, amphibians are expected to continually adjust the relative amounts of time that they spend […]

The dynamics of habitat choice: low-oxygen areas can be safer

June 1, 2016

Comments Off on The dynamics of habitat choice: low-oxygen areas can be safer

Animals should spend more time in habitats where their predation risk is low and their foraging rewards are high. However, habitat use is also affected by the degree of physiological stress imposed by environmental factors such as oxygen, pH, salinity and temperature. Because prey are under greater selective pressure from being eaten than predators are […]

Remote surveillance:monitoring fish populations

June 1, 2016

Comments Off on Remote surveillance:monitoring fish populations

Submerged vegetation provides freshwater animals with food, substrate and refuge opportunities. Although the structural complexity of aquatic vegetation can make it difficult for researchers to study the behaviour of resident species and measure the size of their populations, the advent of high-resolution, low-light video systems promises to alleviate these problems. Working in Florida, researchers carried […]