Showing posts with label embryonic diapause. Show all posts
Showing posts with label embryonic diapause. Show all posts

Monday, 9 October 2023

Bats

 

Bats

Britain's largest bat, the Noctule, is about 8cms (3") long, It eats moths, chafers, mayflies and flying ants and lives for about 5 years.

Image courtesy of Wikimedia Commons

We had a sad little WhatsApp message from Susannah last night:-

‘The cats just murdered a bat in the house😨’

I was quite impressed by that, though feeling sorry for the bat, and thinking that cats were not likely bat predators. How wrong I was! When I looked for more information I discovered that cats are responsible for a great number of bat fatalities. They can hear bat calls and may sit just beneath a roost and leap to catch bats as they emerge. They are thought to be among the most significant predators of bats, along with owls, principally the barn owl and the tawny owl.

The advice to concerned cat owners is to keep their cats indoors half an hour before and one hour after sunset. However, Susannah’s unfortunate ‘guest’ was in the house, so asking for trouble, dicing with death, in fact.

Although I find these furry flying mammals very interesting, they are not very attractive with their pug noses. They don’t really look like pretty little mice with wings!

                                                          Noctule
                                          Image courtesy of Wikimedia Commons

Worldwide, there are more than 1,400 species of bats and the majority are nocturnal. Around ten species are diurnal. They are the megabats, the flying foxes or fruit bats.

Almost a quarter of UK mammals are bats. There are 18 species, ranging from the Pipistrelle, (Pipistrellus) the smallest and commonest, to the largest bat, the Noctule (Nyctalus noctula). Pipistrelle comes from the Italian ‘pipistrello’, meaning bat.

Britain's smallest bat, the Pipistrelle, is less than 5 cms (2") long. It can live for 4-5 years and will eat 3,000 insects a night. Its diet consists of flies, moths, midges and mosquitoes.

Image courtesy of Wikimedia Commons

All UK bats and their roosts are protected under European and UK legislation because these small mammals have been significantly in decline for a few decades. There are many reasons for this, including a loss of habitat and a considerable decrease in insects.

All British bats hibernate. They are one of only three British mammals to do so, the other two being hedgehogs and dormice. Bats usually start hibernating in November, when cold weather has significantly reduced the insect population. When they hibernate, their bodily functions slow down, using less energy. Their heart rate, which is over 1,000 beats per minute in flight, reduces to around 20 beats a minute. Their breathing also slows. The decrease in metabolic activity enables the bats to survive for longer on the fat reserves they built up prior to hibernating. In warmer spells in the winter the animals may wake up and fly to different locations or seek food before going back into hibernation.

Bats hibernate in a variety of places. About three quarters of them roost in trees, others enter caves or tunnels, while yet others find shelter in barns or the roofs of houses. They have no means of drilling holes in trees or making nests so use whatever they can find.

Bats mate in the autumn but the females store the sperm so that they become pregnant in the spring. Delayed implantation (embryonic diapause) is a strategy used by around one hundred mammals, including stoats, badgers, rodents and roe deer.  In this way, the bat pups develop at a time when food is more readily available.

 Bats emerge from hibernation in May. Babies are born between the middle of June and August and are fed by their mothers for four to five weeks, until they are strong enough to fly. When they are very small, they cling to their mothers while they fly out to catch food. Once they are too heavy to carry, their mothers leave them holding onto a wall, or branch while they hunt for food.



'An  Inconvenience' by John Banister Tabb

To his cousin the Bat

Squeaked the envious Rat,

"How fine to be able to fly!"

Tittered she, "Leather wings

Are convenient things,

But nothing to sit on have I."

Father John Banister Tabb (1845-1909) was an American poet, Roman Catholic priest and professor of English

Saturday, 15 September 2012

Roe deer


The doe is watching the dogs pass by
The deer in our local forest are roe deer, the most numerous of Britain’s native deer, and at this time of the year their coats have changed from the dark grey or brown of winter to a rich russet. It is quite usual for us to see one or two roe deer when we take the dogs walking, particularly towards evening. The deer are watchful but not easily startled, only taking flight if one of the dogs gets within twenty yards. Then they bound away and melt into the trees. 
Here she's watching Barry, trying to understand what he's doing
 We have often seen deer lying down in patches of sunlight. This gives them an opportunity to chew the cud. Usually they lie where they have been feeding only if they feel secure. One of the places we have seen them is about a hundred yards from the path we follow.
It's difficult to get buck and doe together in one frame!
In the last three weeks, since late August, we have regularly seen a young buck and doe. They are keeping company because this is the breeding season. The rut takes place from July to September. Does usually bear twins which are born the following spring, between April and June. In exceptionally good conditions a doe may have triplets. 
He looks as though he's saying, 'What are you looking at?'
Roe deer are the only deer that delay implantation so that the young are born when conditions are favourable, in that the weather is more clement and there is sufficient food and fresh plant growth. Others among the one hundred or so mammals that delay implantation (embryonic diapause) include stoats, badgers and rodents.
Spotting them is sometimes difficult . . . 
Can you see him now?
Here he is lying down 
Moving away unhurriedly
 I found a useful site that shows how to calculate the age of a buck by its antlers and I think ‘our’ buck is a two-year-old.

The antlers are shed each year and unusually for British deer, the roe buck casts and regrows them in the winter when good food is not readily available.

I am linking to Camera Critters.