2022 Early Hearing Detection & Intervention Virtual Conference
March 13 - 15, 2022
9/28/2018 | 1:40 PM - 1:55 PM | Factors Limiting the Recovery of Red Grouse Lagopus Lagopus Scotica on a Scottish Grouse Moor | Eccles Conference Center Auditorium
Factors Limiting the Recovery of Red Grouse Lagopus Lagopus Scotica on a Scottish Grouse Moor
Understanding demographic mechanisms is key to managing animal populations in conservation and game management. Here, we consider factors limiting the population recovery of red grouse Lagopus lagopus scotica on a Scottish grouse moor following restoration of management aimed at resuming economically sustainable harvesting. First, we used retrospective analysis to identify the demographic rates explaining variation in population change, and assessed life-stage specific causes of mortality. When demographic parameters were based on annual grouse counts, a combination of adult summer and winter survival appeared to contribute most to population change, when based on radio-tagged individuals, it was adult summer survival and chick survival. Analysis of grouse carcasses suggested that predation by raptors was the main apparent cause of adult mortality, reducing the rate of population recovery. Second, we examined whether the restoration of heather Calluna vulgaris moorland may help mitigate the impact of raptor predation by increasing grouse productivity or survival. Increased heather cover was associated with increases in pre-breeding grouse densities but not with increases in post-breeding densities, largely because neither productivity nor adult summer survival were related to heather cover. A positive association between apparent winter survival, estimated from counts, and heather cover was not supported when considering ‘true’ survival from radio-tagged individuals. This may be explained by post-dispersal settlement if juveniles preferred to move into areas with more heather. Thus, whilst heather restoration has the potential to increase grouse carrying capacity, it did not here because predation, principally by raptors, suppressed grouse productivity and survival.
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Presenters/Authors
Sonja Ludwig
(), Game & Wildlife Conservation Trust, sludwig@gwct.org.uk;
ASHA DISCLOSURE:
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David Baines
(), Game & Wildlife Conservation Trust, dbaines@gwct.org.uk;
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