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By Martyn Stenning
December 2017
I almost missed the deadline for this month so I am taking the opportunity to publicise my book
instead which can be ordered at:
https://bloomsbury.com/uk/the-blue-tit-9781472937391
About The Blue Tit
Sporting a mix of blue, yellow, white, green and black,
the unmistakable Blue Tit echoes the hues of an Earth that
is becoming increasingly populated. Blue Tits have adapted
well to modern humanity, taking advantage of our
propensity to feed birds and provide nest-boxes. In turn,
this charismatic species provides an excellent model for
research, and currently features in around 100 scientific
papers annually. This new Poyser monograph is the result
of a personal quest by author Martyn Stenning to bring
these discoveries together in one accessible volume.
The text initially invites readers into the intimate life
of breeding Blue Tits and describes how nature has shaped
their destiny. Moving on to the diversification and
classification of Blue Tit variation across their range,
the story progresses into population structure, life-time
ecology and mortality, culminating in an exploration of
factors that determine breeding success. The book
concludes with a genial selection of anecdotes, folklore
and poetry.
Table of contents
Chapter One - Beginnings
Chapter Two - Taxonomy, distribution and variation
Chapter Three - Population structure, demography and
mortality
Chapter Four - Determinants of Blue Tit breeding success
Chapter Five - Blue Tits in research; history, methods and
applications
Chapter Six - Anecdotes, Folklore and Poetry
Glossary
References
Due in the shops 22nd February 2018 but there is a
pre-order discount.
November 2017
I am due to give a talk about blue tits in
Norway later this month (October), so I thought I would
rehearse some of it here.
DNA studies have revealed that the ancestors of blue tits
originated in China about 7 million years ago. They
dispersed across central Asia to Europe and eventually North
Africa. Since then, a series of ice ages and climate
changes caused these ancestral blue tits to go extinct,
leaving the North African population isolated. Here
their plumage probably attained its colourful blue, yellow,
green, black and white tones. That is, all the colours
that can be seen from space when looking at our
planet. African birds tend to be colourful, because
the brightness of plumage is an honest signal of health and
freedom from parasites. Parasite abundance increases with
proximity to the equator. About 3 million years ago,
these African blue tits colonised the Canary Islands,
forming new isolated populations on 7 of the islands, there
are now 4 recognised species of blue tit on the archipelago,
the Tenerife blue tit, the Fuerteventura blue tit, the Palma
blue tit and the Hierro blue tit.
Meanwhile, about 5.33 million years ago, the Mediterranean
Sea formed when a sun-parched salty crater separating Europe
from Africa filled with water from the Atlantic Ocean via
the Strait of Gibraltar. This historic event is called
the Messinian salinity crisis and the Zanclean flood.
After this, it became possible for the isolated blue tits of
North Africa to recolonise Europe. They spread north,
dispersing through Spain, France, central and eastern
Europe, eventually reaching Britain where they again became
semi-isolated forming our own sub-species of blue tit (Cyanistes
caeruleus obscurus). Blue tits are still
colonising Finland right now, and are being found further
north each year. A few are now even breeding north of
the Arctic Circle.
As blue tits moved north and particularly east, they became
paler, eventually losing much of the blue and yellow of
their western cousins. Another species was formed;
this is called the azure tit (Cyanistes cyanus).
Then as azure tits spread back into the warmer regions of
Central Asia, they began to re-acquire their yellow hues on
their chest, and yet another species was formed north of
India and parts of China. This species is known as the
yellow-breasted tit (Cyanistes flavipectus).
October 2017
Continuing with the seasonal theme of change, as I write this we are heading for the autumn equinox when day-length equals night-length the world over. In the northern hemisphere we progress to shorter days, but south of the equator, it is the nights that get shorter – lucky them!
Meanwhile, the planet is experiencing equinox weather with high winds, heavy rain, floods, landslides and all sorts of turmoil. Oceanographers have measured the temperature of the oceans getting warmer. This leads to more evaporation of the seas and loading of water vapour in the atmosphere. This has the effect of energising the movement of air and results in the wind and rain extremes we have experienced. This has consequences for wildlife as well as humans. Migrating birds can get blown off course and end up in strange places. For example, I went for a walk along the Cuckmere Valley recently and saw an American Baird’s sandpiper on the wrong side of the Atlantic, busily hunting small invertebrates along the waterline of a meander. There were also many winchats aggregating before venturing forth across the English Channel to France and on to Africa. I was also blessed to see two peregrine falcons and three ravens annoying each other in the sky. The ravens eventually flew off into Friston Forest.
The migration away from the northern breeding grounds is usually quite slow, taking up to three months in many cases. There is no real imperative, as the birds are simply following the tide of insect abundance as it also recedes south. Most northern insects will die during the autumn, either due to weather or to being eaten by the seasonal abundance of spiders. Also, most birds will be moulting and producing a new coat of feathers to see them through winter and help them with migration flights. Incidentally, the spring migration to the breeding grounds is much more rapid, taking as little as three weeks from Africa to England. If you now look carefully at the gulls, crows and pigeons flying over you in the autumn sky, you should see the gaps in the wing feathers caused by the sequential loss of flight feathers. Moulting is a well ordered process which varies according to species. Meanwhile, on the ground, many ducks lose the ability to fly properly as they can be too heavy when they lose some of their feathers. They also often go brown for camouflage, this is called going into eclipse.
September 2017
The coast of Sussex with the calm waters
of summer is a hive of animal activity. Shoals of fish
such as herring, mackerel, sea bass, whiting and cod will be
streaming up the channel. In turn these fish will be
followed by numerous cormorants and gannets, also sandwich,
common and little terns. Other avian predators include
herring, lesser black-backed, black-headed and other
gulls. All these birds will join the seals in hunting
the fishy bonanza, many of them will be feeding nestlings
and teaching fledglings how to feed themselves. It is
fascinating to watch the gannets plunging into the sea at
maybe 20 mph with a splosh as they grab a fish just below
the surface. Binoculars or a telescope are needed to
watch this usually, but recently I have been able to see
this with my naked eye from Bexhill beach. The seals,
usually only one or two at a time, just loaf about in the
calm water often with just their heads showing above the
water surface in the sun-shine.
Meanwhile, on the shore, dozens of turnstones turn stones
and seaweed over to find little crustaceans beneath which
they catch and eat, enjoying them as much as a human with a
pint of shrimps or prawns. These little wading birds
are so well camouflaged in their brown, black and white
plumage that they blend into their surroundings, unseen
until they move. They are amazingly tolerant of humans
passing by. Herring gull fledglings have been making
their maiden flights from nests high on the roofs of coastal
buildings, screaming as they do so and their parents and
other adults nearby excitedly encourage them with a further
cacophony of calls.
A walk along the beach may reveal plants growing out of the flint shingle. Those that do grow in this salty and exposed habitat are called halophytes or salt-loving plants. In truth, these plants are simply the few that are salt-tolerant, because salt will kill most common plants. The plants of the shingle beach include sea-kale, sea beet, yellow-horned poppy and rock samphire. These plants often support insects and produce seeds that are attractive to birds. Yesterday I saw a migrating wheatear perched on a sea kale plant, probably looking for insects. The bird was getting ready to fly across the channel and on to Africa for the winter. Linnets were also looking for whatever they can find among the plants.
August 2017
The woodlands of the British Isles have
had a strange and interesting history. The Younger
Dryas ice age lasted for about 1300 years during the late
Pleistocene from about 12,800 to 11,500 years ago.
During this ice age, a vast ice sheet covered Britain
down as far as about the Thames Valley. South of that,
it was still too cold to support the lush forests we see
now. The habitat was probably tundra as experienced
now on places like Svalbard where just a few dwarf willows
grow in the summer when the ice melts. By about 10,000
years ago, Britain was experiencing temperatures slightly
warmer than now.
As ice retreated, the forests of Europe spread into the land
we now call Britain. This process took hundreds of
years and was probably begun by various willows, Hairy and
Pendulous Birches, Juniper and Scots Pines. Our two
native oaks were probably introduced by the Eurasian
Jay. Often also called the Oak Jay, this bird
obsessively collects acorns in the autumn and carries them
to open areas and buries them in the ground. Many of
these acorns are forgotten about by the birds and they
germinate to form new oak trees. It is thought that by
doing this, oak trees spread through northern Europe at a
rate of about one kilometre per year. Once everything
had moved in, the English Channel formed.
Woodlands develop by a process called succession. From
bare ground the first plants to grow may be mosses and
grasses, then broad leaved herbs such as daisies, dandelions
and thistles. Then small shrubs arrive, like hawthorn,
Hazel and field maple followed by birches, willows if it is
damp and then high forest trees such as Scots Pines,
Pedunculate and Sessile Oaks, Sycamores, Ash, Hornbeam and
Elm. This process can take 50 years or more, and the
woodland will not be properly mature until it is at least
100 years old. Indeed, we cannot refer to woodland as
truly ancient until it is about 400 years old. By that
time it has built up a huge biodiversity of dozens of
species of ground flora like Bluebells, Wood Anemones, Wood
Sage, Wood Sorrel, Bramble and ferns such as Bracken and
Broad Buckler Fern. Also, the wood becomes full of
hundreds of species of fungi, bacteria and animals such as
Spring-tails, Woodlice, Wasps, Moths, and other insects.
Then spiders, frogs, snakes, bats, birds, Wood Mice,
Dormice, Weasels, Hedgehogs, Foxes and Badgers arrive.
Finally, maybe, in come Deer and Wild Boar.
July 2017
When it comes to breeding, some birds,
like blue tits, have just one brood in a year and others are
multi-brooded such as swallows, which mostly feed on
flies. Single brooded species are generally
constrained by the availability of suitable food to feed
their nestlings. In the case of blue tits this is
green caterpillars that are most abundant in oak
trees. One brood of about ten blue tit nestlings and
their two parents require from 700 to 1000 caterpillars
every day. These caterpillars are only available from
about mid-April to about mid-June. Consequently,
British blue tits cannot breed during months outside these
three.
It takes about two weeks for a female blue tit to build her
nest out of honeysuckle bark, moss, feathers and fur.
Birds can only lay one egg per day, so when she is ready,
the female will take about ten days to lay her clutch of
eggs. Eggs can remain cold and dormant, but still
viable, for several weeks if necessary. On average,
the hen blue tit will start to incubate the eggs just before
laying the last one, but it can start as early as five days
before this time or even six days after she finished
egg-laying. It all depends on when the local
caterpillars start to appear. It then takes two weeks
to incubate the eggs before they hatch, which is usually
during May. The blue tit is trying to synchronise most
of her brood to hatch at the best time for catching
caterpillars. If she incubated some days before clutch
completion, her nestlings will hatch over several
days. Or if she waited until all her eggs were laid
before warming them, they will all hatch on the same
day. It will be a minimum of 18 days before her oldest
nestlings are ready to leave the nest, and when they do, the
others will usually follow on the same day, however
well-developed they are.
So that is 14 days for nest-building, then a rest for about
six days, 10 days for egg-laying, 14 days for incubation,
then 18 days for the nestlings to grow. That is a
total of 62 days from the start of nest-building to the
fledglings leaving the nest. In Britain, it is
impossible for blue tits to produce more than one family per
year, because the caterpillar season is so short and the
clutch size so large. However, some blue tits on the
island of El Hierro in the Canary Islands frequently find
time to raise two small broods of about five every year.
June 2017
Continuing with the marine theme,
sea-birds are moving along the coast; generally, from west
to east during May. They are following the fish and
heading for breeding grounds. These birds include
Sandwich Terns, Common Terns, Arctic Terns, Little Terns,
Pomarine Skuas, Arctic Skuas, Black-throated Divers,
Red-throated Divers, Great-northern Divers, Bar-tailed
Godwits, Black-tailed Godwits, Common Scoters Velvet
Scoters, Red-breasted Mergansers, Whimbrel and
Gannets. They have spent winter at sea and on coasts
in warmer latitudes. Some of these birds may be
understandably unfamiliar to some readers; because in order
to see these birds it is usually necessary to be on a
suitable beach at about 6:00 am on a sunny calm morning in
May with a pair of good binoculars and a telescope.
This can be rather cold and frustrating, but when the birds
start to appear, it can get quite exciting. Observers
often post their sightings on the Sussex Ornithological
Society on-line web-pages. Popular beaches include
Selsey Bill, Splash Point in Seaford and the beach at Rye
Harbour.
These and other sea-birds are heading for their breeding
grounds, a few of these birds breed on Sussex beaches, but
such sites are very rare. Others are heading for
North-West Europe, and in the case of some of the Arctic
Terns – the Arctic Circle and the Svalbard archipelago.
It remains that marine habitats are fragile, and when they
are close to Human populations, they get disturbed by
visitors, boats, fishing, dredging and other Human
activities. It is often difficult for these birds to
find a quiet spot to lay their eggs and raise a
family. This is why such places as the Rye Harbour
Nature Reserve exists and volunteers protect the habitats
from too much disturbance. However, it is often
possible to watch from special hides strategically placed to
protect the birds but allow visitors to see them nesting and
raising their young. Entry to Rye Harbour is free, but
a good level of fitness is required to walk around the site
which takes a minimum of about 3 hours for a reasonably fit
person. There is a visitor centre where information
can be obtained and simple refreshments and souvenirs can be
purchased.
Understanding and protecting nature has never been more
important as the Human population continues to increase
beyond 7.5 billion.
May 2017
I am now in Bexhill on duty with my wife
caring for my elderly Mother-In-Law. However, the
weather is beautiful and the sea calm. A few weeks ago
I saw a Seal swimming about 100 metres off the beach moving
due west. I often write about the change of seasons,
but rarely about how this affects marine organisms.
The temperature off the coast of Southern England normally
varies from about 10°C in the winter to about 18°C in late
summer. In recent years it has reached 20°C on
occasion. The sea tends to be rougher in the winter
with storms moving huge amounts of material such as pebbles
and sand. These storms also cause the erosion of
cliffs, and coastal soil. The coast-line is forever
changing.
The animals in the sea also move with the seasons, and cold
water fish like Cod will migrate north in the spring.
Later in early summer baby Herring will move north followed
by Mackerel which feed on them as they move.
Cuttlefish will lay their eggs among coastal rocks and these
will hatch out to produce a new generation. Meanwhile
the older Cuttlefish die and quickly decay leaving only
their white Cuttlebone which often washes up on our shores
in large numbers. In recent years, marine nature
reserves have been created off the coast of Sussex.
Meanwhile, on the beaches, plants, which because of their
habit of growing near the sea, are called halophytes or
salt-loving, are emerging through the pebbles and
sand. These halophytes include Sea Kale, Sea Beet,
Yellow Horned Poppy, Rock Samphire and Thrift. These
plants cannot grow away from the coast, just as other plants
such as Foxgloves, Primroses, Violets and Celandines cannot
grow on a beach.
In Bexhill and other places in Southern England we also have
a rather beautiful alien invader called Hottentot Fig,
brought here by Humans from South Africa, which likes to
grow on cliff edges and has a lovely white or pink
flower. However, like many other alien invaders, this
plant takes over habitat normally occupied by native
species. A fascinating and tasty native plant with the
Latin name Salicornia, that tends to grow on salty
mud-flats is Glasswort, also known as Marsh Samphire and
Pickleweed, because it can be pickled in vinegar, this is
often sold in French shops as Salicorne.
April 2017
I am in France as I write this
edition of NN in early March. Spring is well on the
way here with many singing birds. In the garden
birds include a pair of Stonechats, a Robin and a pair of
Black Redstarts, all busily doing the things birds do in
the spring. Yesterday evening I saw a Black-Winged
Kite, a bird normally confined to Spain. I had heard
talk of this bird in the region, but had never seen this
species before. This morning I was delighted to see
a female Hen Harrier flying over the fields and a Hoopoe
fly from a tree in the garden, and two days ago I heard a
Golden Oriole singing in the Poplar woods nearby. Also
this morning I also encountered a flock of Siskins, these
are winter visitors from Scandinavia and Russia.
They were probably moving north to get back to their
breeding zone for when the snows have all melted later
this month. I also heard a Chiffchaff singing, the
first spring migrant usually heard at this time. Ten
days ago, I was really excited to see chevrons consisting
of hundreds of European Common Cranes flying over the
house in the evening, calling to each other as they
flew. These huge migrant birds over-winter in North
Africa and Spain, then fly north-east to Scandinavia,
Eastern Europe and Russia to breed. Indeed, a few
pairs of Common Cranes breed in Britain.
Here in France the plants too are responding to the longer
days. Celandines like little suns beaming from the
grassy banks. I was also delighted to see Viper’s
Bugloss and Cuckoo Flower in full flower at the woodland
edge. Indeed, all the herbage is growing fast and
many shrubs are adorned with blossom, encouraged by the
spring rain and the appearance of Bumblebees to pollinate
the flowers.
The spring equinox is a time of change, when the
hibernating animals such as Dormice, Hedgehogs and Frogs
emerge from hibernation. Insects too hatch out from
eggs, pupae and hibernation to begin a new
generation. The Earthworms come to the surface
providing food for badgers and blackbirds while also
aerating the grasslands. Winter visiting Redwings
and Fieldfares return to Scandinavia and Siberia, while
the spring migrants from Africa flock into Europe to
replace them. Listen out for a Cuckoo, and look out
for the first Swallow or House Martin. If you have
sight of a bird nest-box, watch it for a while to see if a
Blue or Great Tit enters, then look regularly to see if it
stays.
March 2017
I am delighted to say that new spring
signs are appearing everywhere. Hazel catkins and red
flowers are showing well, frog spawn is being laid in ponds,
snowdrops are appearing all over the place and the first
daffodils have bloomed. Not only that, but I have seen the
first green shoots of hawthorn and the cow parsley leaf
fronds are growing fast.
Many birds such as song thrushes, blue tits, great tits and
starlings are regularly singing, and the occasional insect
can be seen flying on mild days. I have even seen magpies
building a nest.
However, winter is not over yet, and as I write on 10th
February a cold easterly blast has started blowing across
the British Isles. Having said that, the days are getting
longer by about 4 minutes each day, and no bad weather can
change that. On about 21st March, daylight will equal
night’s darkness time the world over. After that date,
northern hemisphere days will get longer and southern
hemisphere days shorter until the solstice on about 21st
June. The cycle of planet earth continues and nature
responds accordingly. New life will spring up around us.
I was reading recently a paper by G. E. Hutchinson (1958),
called: Homage to Santa Rosalia, or why are there so many
kinds of animals? The title refers to Hutchinson’s musings
about how nature has allowed two similar species of water
bugs to live together in a Sicilian spring pool next to the
tomb of Santa Rosalia. This led the writer to ponder on why
there are so many species of animals; at that time estimated
to be “about one million described species. Of these about
three-quarters are insects, of which a quite
disproportionately large number are members of a single
order, the Coleoptera, namely beetles”. He goes on to
describe a story, possibly apocryphal, of the distinguished
British biologist, J. B. S. Haldane, who found himself in
the company of a group of theologians. On being asked “what
could one conclude as to the nature of the Creator from a
study of his creation?”, Haldane is said to have answered,
"An inordinate fondness for beetles."
All I can conclude is that in studying nature we are
studying new beginnings in the creation of life as it is
happening now before our eyes. However it started, the
natural world is forever changing in an astonishing way, a
constantly wonderful series of new beginnings.
February 2017
I nearly missed the deadline for these
Nature Notes. The reason was that I was too pre-occupied
with writing my book, due to come out later this year on
Blue Tits. I am embarrassed to say that NN had slipped my
mind until the all-vigilant Editor contacted me to see what
had happened. Therefore, I hope you will forgive another
note about Blue Tits? It is winter, and Blue Tits are on my
mind, so let’s think for a moment about what Blue Tits do in
the winter, and how they survive.
Blue Tits are described as partial migrants. That means that
part of the Blue Tit population migrates and the other part
is sedentary. There are good reasons for that. All but four
native trees in Britain are deciduous, so woodlands become
bare and draughty and food for small birds is hard to find.
Beech nuts are a favourite food for Blue Tits at this time,
but these can be scarce. Additionally, Male Blue Tits have
often already selected the cavity in which they would like
to breed during the following summer, so they stay behind
and defend it vigorously from other animals. Meanwhile,
female Blue Tits are free to search for food wherever they
want to. Most territorial male Blue Tits are more than one
year old and dominant to yearlings. Therefore, the Blue Tit
yearling males and females of any age disperse south and
west, to find milder and safer places to spend the winter.
These are often Reed-beds and people’s gardens. So the
marauding Blue Tits that you see at your feeders are mostly
females and some yearling males.
The Blue Tits that end up in Reed-beds do so because insects
like to hibernate in the hollow stems of Reed and other
large grasses. Blue Tits can be seen peeling them open to
find lunch. The Reed-beds are also dense and sheltered from
winter weather and provide some protection at night for
roosting. Older males, meanwhile, are lunching on such
things as insect eggs, spiders and seeds. In order to cope
with the switch from insects to seeds, the winter beaks of
Blue Tits become shorter and wider, more like the
seed-eating Finches. Male Blue Tits that have obtained a
breeding cavity, sing loudly from the beginning of January
to declare their ownership of a territory. Their song can
sound like ‘see - see - tu-tu-tu’ or something
similar, it can be quite variable. You can hear it right now
in Lake Wood, a focal location for the natural history I am
writing about in my book - to be called ‘The Blue Tit’.
January 2017
Last month’s Nature Notes may have seemed
a bit depressing, so this month I have resolved to write in
a more positive tone. I am currently writing a book on Blue
Tits. These fascinating little birds never cease to cheer me
up as they are so cheerful and resourceful. The colours of
Blue Tits are similar to those of Plant Earth as seen for
space; blue for the oceans, yellow for the deserts, green
for the forests, black for the deepest water and white for
the snowy regions such as the Poles.
Blue Tits are one of the few birds actually increasing in
number throughout their European range. Their ancient
history is fascinating. Their ancestors almost certainly
came from China, and spread across Asia to Europe and
Africa. Then a series of ice ages and other climatic
extremes caused the ancestors to go extinct, isolating the
remaining Blue Tits in North Africa. From there they
colonised the Canary Islands where they diversified but
remained isolated. They then colonised Europe from Africa
and spread north and east, back into Asia and Russia where
they lost most of their colour except for black white and
blue and became Azure Tits. Some of these in Asia developed
a band of yellow across their breasts to become
Yellow-Breasted Tits.
Meanwhile in Europe the Blue Tits spread across Spain,
France Italy and the entire European mainland and then
crossed the English Channel to the British Isles. They are
even now making their way up through Finland and Norway a
little further each year. One even reached Shetland and
another the Faroe Islands recently. One of the secrets of
the Blue Tit’s success is their adaptability. They readily
come to bird tables and nest in the nest-boxes we make for
them. They also use other structures like letter boxes,
drain pipes and even a boxy ash tray at the University of
Sussex where I work.
One other indication of their adaptability is the way they
learned to open milk bottles during the last century when
milk came in glass bottles and were delivered to everyone’s
doorstep. They just took the cream as this portion of the
milk does not contain much lactose which they cannot digest.
They do not like skimmed milk as it makes them ill.
Another reason for their success is their ability to time
their breeding to coincide with the spring flush of moth
caterpillars to feed their babies.