I knee-d a Purple Emperor

The first Purple Emperor of the day landed on my shorts and wandered around my knee for a few minutes, no doubt remarking on my sweaty qualities.  Frustratingly, no amount of contortion could get the beast into focus through the camera lens before it soared off over the woodland canopy.  So began my walk around Broxbourne Woods this weekend.  After the first Emperor of the day they became decidedly scarce for a while and it seemed I would not get a decent photo, unlike Silver-washed Fritillaries, which were everywhere.  I have walked these woods since the 1970s and never have they been so numerous. They were distinctly hard to find in the 1970s-1990s but now every sunny glade seems to have a few. A remarkable change in status.  Likewise the Purple Emperor.  In the early days, every White Admiral was scrutinised in the hope of finding the Emperor.  Now almost full circle, I saw more Emperors than Admirals on my two hour walk.

At Danemead, a Herts and Middlesex Wildlife Trust nature reserve within the woods, Broad-leaved Helleborines were just coming into flower and the exit holes of Goat Moths were still evident in the small group of old trees that they have inhabited for decades.  Back in the depth of the planted conifers, a family party of Firecrests mingled with a large mixed flock of tits and 9 Crossbills chipped away from the top of a Larch.  On the final stretch back to the car park, Purple Emperors at last began to perform; a couple zooming around large sallows, a couple more taking moisture from the damp path and a final individual sucking away at a gate post.

Photos: my feet, Silver-washed, White Admiral and PE.

 

Woodcock on the wane

 

A long wander through my local Wormley Woods coincided with the arrival of the latest BTO newsletter. Woodcock was the connecting factor.  I saw 2 Woodcock; one flushed by me and one by a dog.  Wormley Woods are very popular with dog walkers and cyclists. Even the remote corner I explored had an off-the-leash labrador tearing through it. I doubt I could find any significant area of the wood without a squidgy tyre print or a doggy do.  I later flicked through the BTO newsletter and settled on the feature on the forthcoming Woodcock survey before shifting to the BTO website.  Woodcock have declined significantly in recent decades. The old CBC recorded a 74% decline between 1968 and 1999.  A quick look at the recent Atlas results appear to show that Woodcock in Hertfordshire in particular have dropped away sharply between the last two atlases, with the Broxbourne Woods complex remaining a very small and tenuous toehold in the county.  No-one really knows why they are declining but, low and behold, recreational disturbance, the drying out of woodland, overgrazing by deer and declining woodland management have been put forward as possible causes.  All four could apply to Wormley Woods.  No doubt the Woodland Trust and Natural England are actively considering these issues at this very moment.

It is undoubtedly good that people get out and enjoy wildlife-rich areas, including nature reserves, as human indifference to wildlife is arguably its greatest threat.  Yet disturbance to the very wildlife that we are encouraging people to visit and enjoy is a real issue that can be subtle in its effects.   Research has shown that disturbance can affect settling rates and patterns of breeding birds, lower their productivity, and can result in reduced densities and delayed breeding.

Studies of Nightjar (formerly present in the local woods but now gone) have found a reduction in breeding densities on sites heavily used by people and dogs.  Increased nest failure due to daytime egg predation was found to be the cause, particularly where nests are close to paths.  The theory goes that as sitting birds are flushed from nests, the eggs are exposed to predation, with the main predator suspected to be crows.

The distribution of Woodlarks on Dorset heaths was also found to be significantly affected by the presence of people and dogs.  Within sites with recreational access, the probability of suitable habitat being colonized was lower in those areas with greater disturbance; this was reduced to below 50% at around eight disturbance events per hour. However, there was no effect of disturbance on daily nest survival rates.  Birds on sites with higher levels of disturbance fledged more chicks (per pair) owing to a strong density-dependent increase in reproductive output.  However, in the absence of disturbance, overall productivity would be 34% higher.

Further afield, a fascinating study on the island of Ouessant in France showed that visitors had a detrimental impact on the survival of juvenile Chough simply by scaring them away from feeding sites.  Annual survival rates of juveniles were found to be negatively correlated with the number of visitors during August.  The time spent foraging by juveniles was 50% less than expected during this peak tourist month.  Food for thought.  Or not, if it happens to be August.

Big Garden Birdwatch

Okay, maybe it’s an age thing, but I did the Big Garden Birdwatch this year.  Well, it takes me an hour to walk from the house to the car these days (poor feet not big garden), so I might as well do something useful on the way to somewhere better.  I recorded a total of 25 species feeding in the garden during the hour.   I have 3 large seed feeders (nyger/sunflower), fat ball feeders and lots of ‘apple trees’ (half apples spiked onto branches).  Tits dominate by far, Great and Blue Tits are near impossible to count but there are easily 25-30 of each at any one time.  Several Coal Tits are regular and a single Marsh Tit has been visiting frequently all month and duly put in an appearance. 

The ‘apple trees’ are a great hit.  Jays, Jackdaws and thrushes love them.  Even the Blue Tits regularly feed from them.  Single Mistle Thrush and Fieldfare have each ‘guarded’ an area of apples during the cold spell.  The local Sparrowhawk regularly raids the feeders about twice a day.  It deters the tits for a minute or two, but then the flight-line resumes.  It’s a bit like a speeded up arrival at Heathrow; look into the garden and Blue or Great Tits are descending from the large tree to the feeders every few seconds, one after another.  Unlike Heathrow, they increase their arrival rate in the snow.  A quick wait on the arrival branch, onto a spare perch on the feeder, and then away.

I’ve been in this house for about 9 months now.  The commonest bird in my last garden was Redpoll, with up to 40 on and around the nyger.  Greenfinches were the commonest birds on the sunflower feeders.  Just 11 miles away, the avifauna of my new garden has a very different feel.  No Redpolls, very few Greenfinches and zero House Sparrows or Starlings.  Although both gardens are located close to woodland (then Epping Forest, now Broxbourne Woods) the current garden has far more woodland birds, with Nuthatches, Green and Great Spotted Woodpeckers all visiting daily.  However, the highlight of the new garden has been the occasional visits of up to three Hawfinches over the last month. One briefly appeared in a tree at the end of the garden yesterday, but they have failed to come down for seed so far.

Count completed, I did then sneak out for a quick look at the nearby Caspian Gull.  Oooo don’t you just love those tertials?  Hmmm maybe not that much.

Pics above: Marsh Tit, Nuthatch, a busy day on the feeders, Blue Tit on 'apple tree'.

Woodlands - the forgotten wetlands

A walk around my local Broxbourne Woods was rewarded with a now irregular sighting of a Hawfinch, once a frequent bird in these parts. There has been a steep decline in many woodland birds over recent years – Lesser Spotted Woodpecker, Willow Tit and Hawfinch all come to mind. However, this decline is not ‘across the board', with some of the more generalist species doing well. Some of the declines have been linked to changes in woodland structure, but in the case of the Hawfinch, the reasons for the decline are still unclear. There has been a 78% decline in the breeding distribution of the Hawfinch between 1970 and 2010 (although there have been some gains in winter distribution). A large number of hypotheses have been put forward to explain this decline, and they include the impact of increasing deer populations, woodland management practices, and of course, the impact of predators.   Hawfinches are mainly associated with extensive areas of mixed broad-leaved woodland, with mature trees, and with an open understorey. There are hints that they prefer woodlands with wet features and that they have disappeared from sites with high densities of Grey Squirrels. Jays are also suspected to be a major nest predator yet evidence remains anecdotal.

The link with wet features is interesting as the importance of wetness in woodlands is surely undervalued. Visit many woodlands and you will see a network of ditches alongside the rides. Many of these were put in to drain water off the site and allow easier removal of timber. Take Wolves Wood in Essex as an example. The ‘old boys’ will tell you that visiting in spring was a nightmare; flooded paths and mosquitoes everywhere. Well, times have changed. Everywhere is drier, yet many of these woodland ditches still drain away winter rainfall. Flooded paths and mosquitoes are a thing of the past. With many woodland birds declining, the loss of Nightingales, Song Thrush and Willow Warblers from some areas could well be the result of reduced invertebrate food as a result of drier conditions. At Wolves Wood, recent work has been undertaken to block up all the ditches as they leave the woodland and extra internal bunds have been constructed to hold water back in the ditches and ponds. The aim is to try and retain winter rainfall and make the site wetter again. We wait to see if the birds and mosquitoes respond.