This Blog covers nature sightings and related news in the Calderdale area.
It includes all groups - Plants, animals and fungi with links to specialist sites.
Anyone wishing to become a member of this Blog and post sightings please contact us.
If you would like to join the Halifax Scientific Society either email me or come along to the next meeting.
All welcome:
calderdalewildlifeblog@gmail.com
Please contact us about any sensitive records before posting on the blog

Sunday, 29 September 2019

Autumn Crocus walk with Julian

Last Saturday (September 21st) we were led by Julian on our annual Autumn Crocus walk in the Bradshaw area of Halifax. Here are a few photos from that day.


Slender blooms can be easily blown over in the September winds.


Just a small portion of the host at Strine's Beck. We estimated about 1000 blooms in this field! This year there seemed to be more than usual.


3 beauties


A solitary bloom in the sunlight - with attendant insect.


The shadow of the stigma on the outer petals attracted me to this. Note the new bloom emerging at the base. They will continue to bloom until about the middle of October.


Showing the stigma and 2 stamens. The feathery stigma were the source of the prized saffron.


Another shot showing the shadow of the stigma on the outer petals.


We find Swallows nesting in this porch at Holdsworth House every year. This year there were 3 nests. We saw the adult coming to feed this chick although it is already capable of flying and feeding itself.



Talk on Tuesday 8th October


Sunday, 15 September 2019

Pond Dipping session at Cromwell Bottom Local Nature Reserve 14.9.19

We had lots of fun dipping our nets and turning stones over in the water.


This freshwater sponge was under many of the stones just below the weir on the River Calder. We had been given a tip that Crayfish could be seen there but didn't find any.




This unidentified water plant had globular growths on it. Possibly eggs of an animal, but as they were in lots of different sizes, I thought they were part of the plant. Dredged from the pond with the dipping platform near Tag Cut.




There were many of these little fish, Stone Loaches I believe, definitely a species of loach, in the Calder on a pebbly beach on Brookfoot Loop. A Kingfisher obligingly showed us how it could easily catch them, or another species of fish, very close by. 
Previously I had only seen loaches in the River Dee in North Wales.

The Pond Dipping walk was not very well attended, just five people including the leader, suggesting pond dipping isn't thought of  as an Autumn activity. The spring sessions are well attended. Apart from the specimens above, we also found many immature newts still with their feathery gills (Reuben was the champion catcher of these,) and water snails, including tiny bivalves, like miniature cockles from the sea, plus lots of insects including large Water Boatmen and Dragonfly larvae.

With many thanks to the Cromwell Bottom team who gave us access to the cabin with hot drinks/ snacks/ ultra-clean toilets and biological reference material. Much appreciated!



How does a tree branch resist gravity?

We look at tree branches without perhaps realising how they manage to support such massive weights.

It seems that Conifers and Broadleaves have evolved different solutions to the same problem but both of them use what is known as "reaction growth".

Reaction Wood forms as a response to gravity and has different cell structure to normal wood, giving it extra strength, whilst laying down much wider rings which give extra bulk. The resultant cross section is often elliptical, particularly in conifers (as seen in photo below).

Broadleaved trees produce Tension Wood on the upper side of a branch, pulling the branch upwards.

Whereas Conifers produce Compression Wood on the underside of a branch, pushing the branch upwards.

Tension Wood has more cellulose and contains a specialised gelatinous layer in the cells, which is rubbery in texture.
Compression wood produces much more lignin and this altered, stronger growth has been utilised by hunters in the American Arctic to make bow staves from trees that were otherwise unsuitable.



                   Conifer with large bulge of compressive growth below the sideways trunks



                              Ash tree showing tension wood on the upper side of this huge branch



                            Conifer adapting with compression wood pushing against gravity



Conifer with unusual growth pattern



   Conifer with lost branch showing the wider rings (compression wood) formed on the underside

Tuesday, 3 September 2019

Hedgehog



Recent short video from Lynn D