In this week's blog, Visitor Experience Intern Naomi Wadsworth gives an overview of the lives of these special residents of Leighton Moss, and the conservation work being done to support them:
This blog is not a recent sightings blog, but will focus on one popular species of bird which is showing remarkably well at the moment - the beautiful bearded tit. John Wilson and David Mower graciously provided a lot of the information found in this blog, and I am very grateful for their input. We have had plenty of bearded tit sightings here at Leighton Moss, with the lion’s share being along the causeway on the newly-installed viewing platform. Thank you to our intrepid Estate Worker Richard Smith for providing such an excellent place to view these lovely birds.
Furthermore, a new exciting development is that bearded tits are now regularly using the grit trays we installed close to the Grisedale Hide. Adults often bring the juveniles to where they grit, so to see them at a new grit site gives me high hopes for the future and perhaps hints at birds arriving from a different area.
As always, the best time to see these birds is in the morning (as a guideline we suggest 9-11am). They have been sighted in the afternoon, but this is very infrequent. Bearded tits prefer dry, calm weather for gritting. Heavy rain or high wind conditions reduces the chance of sighting these birds.
Male bearded tit, by David Mower
Identification
For those who are unfamiliar with this species, the male of the species is often the most referred to. I have had the pleasure of attending a ringing session with one of our qualified members of staff, and it is truly a privilege to see this bird up close. Typical identifying features of the handsome male are his lovely lavender-blue head and chest topped off with a broad, black moustache running from his eyes down his cheeks. So really, the males do not have a beard at all! Males also have bright ginger-brown upper parts and distinctive black and white markings on the wings and tail which make for a very photogenic appearance.
Females share a similar plumage to the male, but their head is the same colour as their upper parts and they lack the distinctive moustache. The juveniles are also stunning birds, with a bright ginger plumage and extensive black markings down their back and wings. The most reliable way to know the sex of a juvenile is to look at their beak colour - only males have yellow beaks. In saying this, juveniles moult into their adult plumage in their first year, so there is a relatively short window to sight a juvenile.
Female bearded tit, by Martin Kuchzynski
A brief history
Historically, many of the UK’s reed beds were drained for intensive agricultural and developmental purposes. In a previous life, Leighton Moss was known as the Golden Valley, full of fields of wheat (no Theresa May however!) Unfortunately, bearded tits are reed bed specialists and the population declined as a result of habitat loss amongst other factors such as unfavourable weather and even egg collecting. The winter of 1947 saw bearded tits in the UK come dangerously close to extinction, with just 10 pairs left in Norfolk, East Anglia.
The UK population was supplemented by an increasing Dutch population of bearded tits, with birds recovered in the UK originating in Holland. Bearded tits were first seen at Leighton Moss in 1965, but they did not breed here until 1973. Quite ironically, the first bearded tits to breed here chose a small patch of National Rail reed bed, instead of the neighbouring 75 hectares at Leighton Moss! Since then there has been a continued presence of the species with a peak of 65 pairs in 2000. This then plummeted to just seven pairs in 2001, due to bad weather. This year we have roughly 25 pairs, with 29 newly-ringed birds so far. The ongoing ringing study being undertaken by John Wilson has provided an incredible insight into this species and a thorough, reliable way of monitoring the population. If you have any photos of ringed bearded tits at Leighton Moss, do continue to send them to us at leighton.moss@rspb.org.uk and email John directly at john.wilson@rspb.org.uk.
Ringed bearded tits on grit trays, by Richard Cousens
Breeding
John’s study has provided evidence which demonstrates bearded tits are one of two species known to pair up as juveniles. Adults rarely survive to be older than 5 years old and they will remain monogamous if they are a successful breeding pair. A pair can have up to three broods per year, with a varying clutch size. Water levels can also affect the success of a pair, so to help them our ex-warden David Mower pioneered the nest boxes we use now (photo below). I have made one with guidance from David, and it is a very physically demanding task. I now have a much better appreciation of the dedication and effort it takes to make them. These boxes can be raised, which helps increase the chance of survival as this prevents the nests from being flooded. It is also a way of circumnavigating reed bed management clashes of other reed bed dwellers: bitterns like young reed bed with plenty of water movement whereas bearded tits prefer dense reed bed. I should mention birds also nest naturally at Leighton Moss.
Bearded tits do disperse to new areas. When this happens it is described as an irruption. Autumn is a good time to watch the birds go into an excited state, circling the reed bed and being carried away with the wind (if the weather is preferable) to new sites. Nevertheless, they may return to the initial site.
Ex-Warden David Mower placing a bearded tit 'wigwam' in the reedbed, by Ben Hall (rspb-images.com)
Interesting Choices
In spring and summer, bearded tits prey on insects, but when these become scarce they are forced to switch their diets to reed seed, which has led to a rather intriguing behavioural adaptation. During autumn, they can be seen ‘gritting’, in which they line their gizzards with tiny stones which enables them to break down the nutritious reed seeds. The birds can spend up to 15 minutes at a time gritting (Wilson, 2013). In one study, a bearded tit was found to have an estimated 650 stones lining its gizzard (ibid, 2013). Whilst hardy birds, bearded tits are vulnerable to water levels in the reed bed. Their dietary choice of reed bed seeds can lead to complications as they prefer to feed on seeds on the bottom of the reed bed, which can be covered by water, ice or snow. Whilst some birds will then feed on seed higher in the plant, many will unfortunately starve to death.
The future?
Leighton Moss remains a stronghold for bearded tits and the birds are gradually spreading to our satellite sites in the surrounding area. This is a great indicator that more habitats are suitable for this precious species and bodes well for future birds. I cannot say how future weather patterns will affect our resident UK population. There are also lots of other RSPB reserves where one may see this species and I am confident in saying that the work of the RSPB in particular has played a vital part in ensuring a brighter future for this attractive bird.
Wilson, J. (2013) The gritting behaviour of Bearded Tits Panurus biarmicus. Lancashire. British Trust for Ornithology. Ringing & Migration. Vol 28. pp 1–4