Is the Blackbird<i>Turdus merula</i>declining in The Netherlands because of lower breeding success?

Dix, Mackenzie J.; Musters, K.; Keurs, W. J. Ter

doi:10.1080/00063659809461096

Cited by 4 publications

(6 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2002). On the other hand, no relationships emerged between local trends in songbird numbers and local trends in Magpie or Sparrowhawk numbers, two predators sometimes suspected of causing declines in songbird populations (Gooch et al . 1991, Dix et al .…”

Section: Summary Of Findingsmentioning

confidence: 99%

The recent declines of farmland bird populations in Britain: an appraisal of causal factors and conservation actions

Newton

2004

Ibis

625

501

View full text Add to dashboard Cite

In this paper, the main aspects of agricultural intensification that have led to population declines in farmland birds over the past 50 years are reviewed, together with the current state of knowledge, and the effects of recent conservation actions. For each of 30 declining species, attention is focused on: (1) the external causes of population declines, (2) the demographic mechanisms and (3) experimental tests of proposed external causal factors, together with the outcome of (4) specific conservation measures and (5) agri-environment schemes. Although each species has responded individually to particular aspects of agricultural change, certain groups of species share common causal factors. For example, declines in the population levels of seed-eating birds have been driven primarily by herbicide use and the switch from spring-sown to autumn-sown cereals, both of which have massively reduced the food supplies of these birds. Their population declines have been associated with reduced survival rates and, in some species, also with reduced reproductive rates. In waders of damp grassland, population declines have been driven mainly by land drainage and the associated intensification of grassland management. This has led to reduced reproductive success, as a result of lowered food availability, together with increased disturbance and trampling by farm stock, and in some localities increased nest predation. The external causal factors of population decline are known (with varying degrees of certainty) for all 30 species considered, and the demographic causal factors are known (again with varying degrees of certainty) for 24 such species. In at least 19 species, proposed causal factors have been tested and confirmed by experiment or by local conservation action, and 12 species have been shown to benefit (in terms of locally increased breeding density) from options available in one or more agri-environment schemes. Four aspects of agricultural change have been the main drivers of bird population declines, each affecting a wide range of species, namely: (1) weed-control, mainly through herbicide use; (2) the change from spring-sown to autumn-sown cereal varieties, and the associated earlier ploughing of stubbles and earlier crop growth; (3) land drainage and associated intensification of grassland management; and (4) increased stocking densities, mainly of cattle in the lowlands and sheep in the uplands. These changes have reduced the amounts of habitat and /or food available to many species. Other changes, such as the removal of hedgerows and 'rough patches', have affected smaller numbers of species, as have changes in the timings of cultivations and harvests. Although at least eight species have shown recent increases in their national population levels, many others seem set to continue declining, or to remain at a much reduced level, unless some relevant aspect of agricultural practice is changed.Widespread population declines of farmland birds are of major conservation concern in Britain and other parts of Europe. S...

show abstract

Section: Summary Of Findingsmentioning

confidence: 99%

The recent declines of farmland bird populations in Britain: an appraisal of causal factors and conservation actions

Newton

2004

Ibis

625

501

View full text Add to dashboard Cite

show abstract

“…We compared ratios of juveniles (EURING age 3: definitely fledged within that calendar year) to adults (EURING ages 4–5: definitely fledged before that calendar year; Spencer 1984). This ratio has been considered an indicator of seasonal productivity (Dix et al . 1998) and we used it to compare productivity before and after cessation of predator control.…”

Section: Methodsmentioning

confidence: 99%

“…Nevertheless, unconsidered interactions between habitat change and predation may have led to inaccurate diagnoses in some cases (Evans 2004). Although there is little evidence that passerine declines have correlated with some nest predator population levels at national scales (Dix et al . 1998, Thomson et al .…”

mentioning

confidence: 99%

Investigating the effects of predator removal and habitat management on nest success and breeding population size of a farmland passerine: a case study

White

Stoate

Szczur

et al. 2008

Ibis

View full text Add to dashboard Cite

Passerines are especially vulnerable to predation at the pre-independence stage. Although the role of nest success in British farmland passerine declines is contentious, improvement in nest success through sympathetic management could play a role in their reversal. Because habitat is known to interact with predation, management options for mitigation will need to consider effects of nest predation. We present results from an observational study of a population of Common Blackbird Turdus merula on a farm which has experienced a range of agri-environment and game-management options, including a period with nest predator control, as a case study to address some of these issues. We used an information theoretic model comparison procedure to look for evidence of interactions between habitat and nest predation, and then asked whether habitat management and nest predator abundances could explain population trends at the site through their effects on nest success. Interactions were detected between measures of predator abundance and habitat variables, and these varied with nest stage -habitat within the vicinity of the nest appeared to be important at the egg stage, and nest-placement characteristics were important at the nestling stage. Although predator control appeared to have a positive influence on Blackbird breeding population size, the non-experimental set-up meant we could not eliminate other potential explanations. Variation in breeding population size did not appear to be influenced by variation in nest success alone. Our study demonstrates that observational data can only go so far in detection of such effects, and we discuss how it might be taken further. Agri-environment and game-management techniques are likely to influence nest predation pressure on farmland passerines, but the patterns, mechanisms and importance to population processes remain not wholly understood.

show abstract

“…These urban populations continue to expand northeastward with a growing number of breeding pairs in towns (Cramp 1988, Luniak et al 1990, Mulsow & Tomiałojc 1997, Collar 2005. Breeding birds here have seemingly better reproductive success compared to birds breeding in rural areas (Batten 1973) however, this difference has decreased in the Netherlands (Dix et al 1998) in the past decades. Urban populations may also be more dense and have higher between-season recruitment rates (Batten 1973 (Havlin 1963).…”

Section: For Details)mentioning

confidence: 99%

“…However, this tendency may have considerable large scale spatial variation. The Finnish breeding population showed a three-fold increase during the last decades (Valkama et al 2014), while in the Netherlands the past two decades produced a decline in the number of breeding pairs (Dix et al 1998). The British population has declined by appr.…”

Section: For Details)mentioning

confidence: 99%

Exploratory analyses ofmigration timing andmorphometrics of the Common Blackbird (Turdus merula)

Csörgő

Fehérvári

Karcza³

et al. 2017

Ornis Hungarica

View full text Add to dashboard Cite

Ornithological studies often rely on long-term bird ringing data sets as sources of information. However, basic descriptive statistics of raw data are rarely provided. In order to fill this gap, here we present the fourth item of a series of exploratory analyses of migration timing and body size measurements of the most frequent Passerine species at a ringing station located in Central Hungary (1984-2016). First, we give a concise description of foreign ring recoveries of the Common Blackbird in relation to Hungary. We then shift focus to data of 6849 ringed individuals and 6081 recaptures derived from the ringing station, where birds have been trapped, handled and ringed with standardized methodology since 1984. Timing is described through annual and daily capture and recapture frequencies and their descriptive statistics. We show annual mean arrival dates within the study period and present the cumulative distributions of first captures with stopover durations. We present the distributions of wing, third primary, tail length and body mass, and the annual means of these variables. Furthermore, we show the distributions of individual fat and muscle scores, and the distributions of body mass within each fat score category. We distinguish the spring and autumn migratory periods, breeding and wintering seasons, ages (i.e. juveniles and adults) and the two sexes. Our aim is to provide a comprehensive overview of the analysed variables. However, we do not aim to interpret the obtained results, merely to draw attention to interesting patterns that may be worth exploring in detail. Data used here are available upon request for further analyses.

show abstract

Is the BlackbirdTurdus meruladeclining in The Netherlands because of lower breeding success?

Cited by 4 publications

References 2 publications

The recent declines of farmland bird populations in Britain: an appraisal of causal factors and conservation actions

The recent declines of farmland bird populations in Britain: an appraisal of causal factors and conservation actions

Investigating the effects of predator removal and habitat management on nest success and breeding population size of a farmland passerine: a case study

Exploratory analyses ofmigration timing andmorphometrics of the Common Blackbird (Turdus merula)

Contact Info

Product

Resources

About