ornithology

How can we manage broadleaved woodland to benefit birds?

Broome et al 2017Although broadleaved woodland, an important habitat for many birds, is increasing in the UK, songbird populations are still in decline. An interesting new review of previous research, combined with a field study by the Forestry Commission, has provided some possible solutions to this quandary.

Researchers studied a representative sample of broadland lowland woodlands in England and Wales, assessing the effect of woodland management (silvicultural intervention and control of deer browsing) on vegetation structure, and the relationships between vegetation structure and woodland birds.

Different bird species have different habitat and resource requirements, which researchers identified from a review of existing literature. For example, while hawfinches mainly forage in woodland canopy, dunnocks forage on the ground and willow tits are reliant on the shrub layer for their foraging requirements. Wood warblers prefer mature woodland, whereas song thrush require woodland in a younger stage of development.

As well as summarising resource requirements for 17 target bird species, the study classified different woodland stand structures from A to F, which related to their value to birds:

A – dense low shrub layer
B – dense high shrub layer
C – open understory
D – open canopy
E – closed canopy, few strata
F – closed canopy, multiple strata

The most frequently occurring structures found currently in lowland broadleaved woodlands in England and Wales were stand type E, which are of least value to woodland birds.

The crucial finding from this research is that a very high proportion of lowland broadleaved woodland in England and Wales is of fairly uniform structure. This lack of structural heterogeneity means that our woodlands are missing the mosaic of habitats which different bird species rely on.

Simply increasing the UK’s area of broadleaved woodland is not enough to help songbird populations recover: these woodlands need appropriate, targeted management to deliver a mixture of different stand structures at the landscape scale.

This research has identified a novel approach, providing woodland owners and managers with practical management advice to increase the biodiversity value of their woodland. Creating a more diverse structure through targeted woodland management practices is essential to provide suitable habitat and resources, and to enable woodland bird populations to thrive.

Read the full research paper here.

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Introducing SongBird Survival’s new research project!

In partnership with the University of Exeter, we aim to find out how we can improve the health and welfare of cats and wildlife. Find out more below:

 https://biteable.com/watch/embed/introducing-our-new-research-project-in-partnersh-1455388

Introducing our new research project, in partnership with the University of Exeter on Biteable.

Corvid Population Ecology Research Update

An update from Lucy Capstick, PhD researcher at the University of Exeter, on SBS’s corvid population ecology research study.

My PhD project (funded jointly by SongBird Survival and the University of Exeter, in collaboration with the Game and Wildlife Conservation Trust), investigating how variation in the ecology and behaviour of Magpies affects their impact on songbirds, is nearing completion. The final season of field work has just finished and over autumn and winter of this year the collected data will be analysed and consolidated.

This project has examined whether individual Magpies differ in the extent to which they predate songbird nests, particularly exploring potential differences between territorial and non-territorial birds. To this end the Magpie and songbird populations of a small mixed farm in Warwickshire have been observed and monitored through spring and summer for the past three years. The continuous use of the same site, a farm with management typical of much of the UK’s rural landscape, has allowed the development of a more detailed picture of the population ecology of both the Magpies and the songbirds. It has also made it possible to investigate variation between years, for example whether differences in weather conditions influence songbird nest success or Magpie food preferences.

magpie

In 2016, as in previous years, songbird nests were located in hedgerows on the field site and monitored in order to assess Magpie impact on the songbird population. However, experience gained in the past two years meant that in 2016 a larger sample of approximately 80 nests was found, and in 50 of these, the outcome (success/failure) was known. The nests found largely belonged to more common species, almost three quarters of nests were Blackbird, Dunnock and Wren, however Goldfinch, Yellowhammer and Whitethroat nests were also located. As well as finding individual nests the territories of songbirds were also identified by mapping singing males early in the season. This information will be related to our knowledge of the Magpie population to see if, for example, the presence of a Magpie territory affects songbird territory location and nest success.

Our understanding of the Magpie population has been developed using a number of techniques over the course of the project. In 2016, Magpies were trapped across the site using Larsen traps for the third consecutive year. Trapped birds were colour ringed so they were individually identifiable. In 2015 the rings were more successfully attached than in 2014, so there was less overwinter loss between 2015 and 2016 than the previous year. Of the 75 occasions Magpies were trapped in 2016, new birds were caught only 10 times, while on the other 65 occasions previously ringed birds were re-trapped. The trapping process was slightly less successful than in 2015 and camera observations of the traps suggested there were a number of occasions of previously trapped individuals returning to traps and, perhaps unsurprisingly, avoiding tripping the mechanism again. Nonetheless, this trapping programme alongside direct observation of individuals and early season identification of magpie nest sites meant it was possible to work out where active Magpie nests were.

As well as looking at how the Magpie population as a whole may relate to songbird nest success, this project also aimed to investigate how individual Magpies differ in their impact on songbirds, for example, are some individuals more likely to predate nests in their territories than others? This year variation in individual Magpie defence behaviour was investigated, largely through work carried out by a Master’s student from Newcastle University (Rebecca Liberty). A dummy Magpie was placed near active nests and the response of the territory holder, which ranged from mobbing the dummy to ignoring it, was recorded. This variation in response, alongside other information such as differences in trappability, may indicate differences in aggression between individuals which could be linked to predation behaviour.

6 - Predated nest

A predated nest. Photo: Lucy Capstick

Another way of examining possible difference in an individual’s predation behaviour is to use artificial nests. This is a recognised technique used to gain an understanding of the pattern of nest predation and the identity of nest predators without disturbing natural nests. Both old songbird nests and manmade nests were baited with real and wax-filled quail’s eggs and monitored by trail cameras (motion activated cameras). A predator attacking a wax egg will leave an imprint, such as a beak or bite mark, and can therefore be identified. The nests were set out in transects in areas with occupied Magpie nests and in areas where it was believed Magpie presence was reduced. This method was piloted in 2015 and used more extensively this year. Over the course of the spring and summer over 400 artificial nests were placed across the field site. It will therefore be possible to look at the impact of Magpie presence on predation, but also at differences between the territories of individual Magpies, and the effect of time of year, for example, is predation higher when Magpies have young in the nest? Preliminary analysis suggests Magpie predation is higher in certain locations and trail camera pictures also identified specific ringed Magpies predating multiple nests. This may indicate that certain individuals predate more.

Over the three years of this PhD project a range of field data, including that detailed above, has been collected. The task now is to look at the information about Magpie population ecology, habitat use and territorial behaviour in combination with that about the songbird breeding population to see if and how they interact. The project will collate information about Magpie distribution, movement and breeding at a wider landscape scale. At a finer scale individual differences between Magpies in terms of territory location and habitat, and behaviour will be examined. Predation of both real songbird nests and artificial nests will be looked at with relation to the Magpie population. As well as this field data, research of the scientific literature will help to build up a more general understanding of corvid predation of songbird nests, as it could be that some species are more vulnerable to predation by corvids or that their populations are less able to recover from breeding season losses. In general this type of research into the population ecology of predators and their prey species, and how they interact, may suggest a way to manage the UK’s countryside to benefit the prey species, such as threatened songbirds.

Urban ecology: noise and light pollution affect how robins sing

A researcher at the University of Southampton has found that robins in urban environments are affected by noise and light pollution.

The study by Frances Mullany used a fake robins to measure how the quality of robin territory was affected by its proximity to a lit path and a road.

Robins hold territories all year round, individually over winter, and as a pair during the breeding season. If you’ve ever strayed too close to a male robin’s territory, you may have encountered their aggression as these feisty little characters defend their patch. Male birds in particular are aggressive and very vocal in defending good quality territory.

Robin Feb 16

By setting up fake birds in different robin territories throughout an urban park, Frances was able to record how aggressively each of the birds in the park that responded, sang and displayed in response.

The study found that the robins that lived closer to lit paths and noisy roads displayed less aggressively than those who were further away.

Although urban pollution didn’t stop robins from singing, it certainly had a marked effect on the birds’ behaviour. The results of this study lay the foundation for further research into why these territories are less well defended, and has interesting implications for urban planning and design in the future.

 

Saving Our Dawn Chorus

What is behind the continuing decline of our songbirds today? What are the underlying reasons and what potential solutions should be investigated?

SongBird Survival is committed to finding out the answers to these questions through commissioning quality scientific research into the issue.

In 2016, we produced a short film, presented by ecologist Katy Thomas, introducing SongBird Survival and looking at where the UK’s famous dawn chorus is heading.

Since the 1970s, populations of songbirds in the UK have crashed, and our dawn chorus is far less rich and diverse than it was in our parents’ and grandparents’ day.

Yellowhammer populations have declined by 55%, cornbunting numbers are down by 87%, whilst tree sparrows have suffered a rapid decline of 95%. These figures are shocking, but what is causing our small birds populations to crash? Loss of habitat? Predation? Intensification of farming?

SongBird Survival believes that research is the key to understanding why.

We fund high quality scientific research to investigate the drivers behind these population declines and promote evidence-based solutions to restore songbird numbers.

With your support we hope to draw attention to the plight of our song and other small birds. Your membership and donations help to fund our research programme and add weight to our work with other organisations. Together, we can save our songbirds before it’s too late.

To find out more about our research and objectives, watch our YouTube video.

SBS YouTube (2)

We partner with like-minded organisations to commission targeted research into areas where scientific evidence is currently sparse, inadequate or lacking.

To date we have partnered with the University of Exeter, the University of Reading, the Game & Wildlife Conservation Trust, and the University of St Andrews, in projects which examine the potential causes behind songbird population decline. Such research produces high-quality, peer-reviewed research papers, contributing to ornithological and ecological knowledge in the UK.

We have exciting future projects in the pipeline, and will be bringing you news of this very soon. In the mean time, further information about our current and past research programmes can be seen on our website.

SongBird Survival: Saving Songbirds With Science