Correlates of Breeding Success of Horned Grebes in Scotland

Summers, Ron W.; Mavor, Roddy; Hancock, Mark H.

doi:10.1675/063.032.0206

Cited by 9 publications

(8 citation statements)

References 21 publications

(8 reference statements)

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“…), as well as studies of artifi cial nest predation in the Troms region (Pedersen et al 2009, Klaussen et al 2010. Furthermore, Summers et al (2009) found a negative correlation between crow abundance and both grebe clutch survival and productivity. Crow and raven are included in the grebe action plan ( Fig.…”

Section: Discussionmentioning

confidence: 84%

Management decisions and knowledge gaps: learning by doing in a case of a declining population of slavonian grebe Podiceps auritus

Stien

Ims

2015

Wildlife Biology

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Species of national conservation concern require management action to reduce the threat of extinction. As part of its obligations to reduce national loss of biodiversity, the Norwegian authority for nature management (The Norwegian Environment Agency) published an action plan in 2010 for one of these species, the Slavonian grebe Podiceps auritus. The American mink Neovison vison, a non‐native, invasive species with wide spread negative effects on native fauna, was highlighted as a major potential treat. We used an adaptive management approach that included management trials with the aim to assess whether mink predation is likely to be affecting grebe numbers significantly. We monitored mink activity, and put in place mink control measures at three of our seven study lakes. We then used 35 pairs of artificial nests, with one of each pair equipped with cameras, to measure predation at all seven lakes. The combined use of progressive experiments in an adaptive management/monitoring framework showed that mink activity was generally low with a mean activity at raft stations of between 0.41–1.22 per lake (n = 5), a range of zero to three excavations executed as a result of hunting (n = 3), and no incidences of mink nest predation (n = 35). Hence we conclude that mink is presently not likely to be a significant negative factor on grebe breeding success in the targeted lakes. We found a high nest predation rate by hooded crow with 18 of 21 identified predation events being identified to this species. Future effort should investigate non mink related threats to the Slavonian grebe such as the role of hooded crow in nest predation. This case study exemplifies the usefulness of the adaptive management/monitoring framework as a powerful means of testing hypotheses and to inform management, especially when knowledge of the focal system is poor.

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Section: Discussionmentioning

confidence: 84%

Management decisions and knowledge gaps: learning by doing in a case of a declining population of slavonian grebe Podiceps auritus

Stien

Ims

2015

Wildlife Biology

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“…Egg destruction was perpetrated only by males, which presumably benefit from the behavior more than females whose eggs were victimized. Previous reports of intraspecific egg destruction in other species of grebes did not report the sex of perpetrators (McAllister 1958, Perkins et al 2005, Konter 2008a,b, Summers et al 2009.…”

Section: Discussionmentioning

confidence: 85%

“…the lake. The natural history of the lake and the anthropogenic footprint on it have been summarized by Suchanek et al (2003).…”

Section: Study Site and Subjectsmentioning

confidence: 99%

Egg Destruction by Males in the Western Grebe and Clark’s Grebe

Hayes¹,

Turner²,

Zimmerly³

et al. 2018

WBirds

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“…Nesting habitats on the majority of these lochs have not suffered gross changes since 1970, so that does not appear to be a limiting factor. Although there are correlations between breeding success and predator frequency, predators do not appear to have a major impact on clutch survival (Summers et al 2009;Perkins et al 2005). The abundance of prey species may be more significant.…”

Section: Introductionmentioning

confidence: 98%

“…Reasons for the population fluctuations remain unclear. Grebe numbers and breeding success may be influenced by a wide range of factors such as the density and number of sedge beds in which the nests are built (Summers and Mavor 1995), the number of small prey fish available, the impact of predators, and fluctuations in water level (Summers et al 2009). In Scotland, pairs have been recorded on 110 lochs and have produced chicks on 59 of them.…”

Section: Introductionmentioning

confidence: 99%

Population trends in the Slavonian grebe Podiceps auritus (L.) and Chironomidae (Diptera) at a Scottish loch

et al. 2012

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Loch Ruthven holds the largest British population of the rare water-bird Podiceps auritus, the Slavonian or horned grebe. The breeding success of this bird has fluctuated annually since records began in 1970. To investigate whether these trends are linked to the abundance of chironomid midges, which are an important food-source for the grebe chicks, we analysed a sediment core from the lake, which was sliced at 2.5-mm intervals and provided near-annual sampling resolution. We also analysed diatoms and algal pigments in the lake sediments and inferred changes in total phosphorus from the diatom assemblage to determine whether changes in lake productivity have influenced the abundance of chironomids. Trends in grebe productivity, chironomid abundance and algal assemblages were compared against climate data to determine whether climate, specifically, the North Atlantic Oscillation, was the ultimate driver of the trends we recorded. Our results show that grebe breeding success is positively correlated with chironomid abundance and chironomid abundance is positively correlated with diatominferred total phosphorus. Lake productivity and chironomid abundance began to rise early in the twentieth century and continued to rise on a steeper trajectory from the mid-twentieth century to the present. Since the mid-1960s, chironomid abundance began to fluctuate erratically and since 1970 was in phase with grebe productivity, with the grebe trends most plausibly lagging by 1 year. These trends appear to correlate with inter-annual fluctuations in diatominferred total phosphorus. No correlation was found between grebe productivity or chironomid abundance and climate variables, suggesting that the size of the chironomid population and breeding success of Podiceps auritus at Loch Ruthven is resource-linked.

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Correlates of Breeding Success of Horned Grebes in Scotland

Cited by 9 publications

References 21 publications

Management decisions and knowledge gaps: learning by doing in a case of a declining population of slavonian grebe Podiceps auritus

Management decisions and knowledge gaps: learning by doing in a case of a declining population of slavonian grebe Podiceps auritus

Egg Destruction by Males in the Western Grebe and Clark’s Grebe

Population trends in the Slavonian grebe Podiceps auritus (L.) and Chironomidae (Diptera) at a Scottish loch

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