Monday, April 11, 2016

Fat Is Good

In amongst the 60+ Siskins caught since Christmas at Oakenclough have been a number with visible fat reserves. Ringers regularly check the birds they handle for visible fat, especially during the winter or at times of migration when high scores can indicate that an individual is in the process of migrating or building up reserves during a bad spell of cold weather. One memorable Siskin of 31st March 2016 tipped the scales at 16.2 grams - Another Bird Blog.

It’s not often there are Siskins in my garden, even in a “Siskin Winter”, a year when the species becomes especially numerous in the early months of the year. If it was going to happen again then 2016 would be likely as good numbers have been reported in many parts of the UK, more so in recent days as large numbers of migratory Siskins head north. 

Today I caught another fat Siskin, a second year female, this time in the garden. This lovely lady weighed a stupendous 16.8 grams, amazing when you think a tiny Siskin normally weighs between 11 and 12 grams. It becomes more remarkable when considering that the bird probably accumulated this amount of extra fat in just a couple of days of short refuelling stops and increased her weight by 30 - 40%. For migrating birds ... it pays to be fat! 

Siskin - second year female at 16.8 gms

Siskin - second year female

Research has shown the strategy allows them to reach their breeding grounds faster and claim the best nesting sites. Small migratory birds sometimes need to take a break to replenish their fat reserves, especially after crossing vast oceans or deserts. Factors known to influence the length of these stopovers are the weather, food availability and internal factors such as a genetically programmed urge to continue the journey. 

The last time I witnessed the build-up of Siskin fat reserves was in the early part of 2011, the last "Siskin Winter" when Will and I caught good numbers in a Garstang garden. Garstang is just a few miles from the current ringing site of Oakenclough, one of the reasons that we chose to re-establish a ringing site here when Will moved from the old location.

In early 2011 we caught 258 new Siskins - 53 in January, 71 in February and 134 in March.  During March it was noticeable that the Siskins were heavier than in previous months and that many carried visible fat for migration purposes.

Average monthly weights:
• January 12.4 grams
• February 12.5 grams
• March 12.9 grams

The ranges in weights were:
• January 10.9 - 15 grams
• February10.9 - 14.9 grams
• March 10.6 - 15.7 grams.

In the garden at home this past weekend the normally ever present Goldfinches have mostly moved out, replaced by small numbers of Siskins and Lesser Redpolls, although both species moved quickly on after devouring quantities of Niger seed. 

Siskin

Goldfinch

Last week’s Nuthatches seems not to have stayed and I fear that something happened to the female when the male continued singing loudly into the third day but nest box activity ceased. It was good while it lasted.

Linking today to World Bird Wednesday.


25 comments:

Linda said...

Such lovely birds, Phil, you are so blessed to be able to see them, and I really appreciate your sharing them via your beautiful photos and posts.

Laura said...

Fascinating info Phil. That last photo of the goldfinch is exquisite!

Fun60 said...

The goldfinch is such a beautiful bird.

HOOTIN ANNI said...

I just saw a Kentucky Warbler in our backyard. I couldn't believe it...we usually have redwinged blackbirds, doves, cardinals and sparrows only. I was thrilled.

Of course, it goes without saying your photos are superb. And now you are making me wanting to a bird!!! It would be easy for me to put on weight...I collect fat cells y'know!!!

NC Sue said...

Your siskins and ours look the same, but our goldfinches don't have the red markings - at least none that I've seen. Quite striking!
Thanks for linking up at http://image-in-ing.blogspot.com/2016/04/the-many-faces-of-louie.html

Chandra@GreenComotion said...

I love your Red Finch photo, Phil - Brilliant!
Have a Happy Day!
Peace :)

David Gascoigne said...

There is nothing here that I don't know, but it is nice to see it laid so precisely. It's a fine post, Phil, filled with good information. No doubt this is all a result of the excellent training you had at Long Point!

Judy Biggerstaff said...

Your goldfinch is much different than the goldfinch that I see around Kentucky, Illinois and Missouri. Thanks, very interesting images.

Stuart Price said...

I saw 3 Siskin yesterday, didn't notice them looking particularly chubby though...........

Nora said...

This was very interesting and informative about the siskins. I have had a lot of them at my feeder this year. The Goldfinches have not come in yet, but soon.

Bill Nicholls said...

Great photo's Phil, did not realise netting was still done but I suppose you have to catch the birds some way

Margaret Adamson said...

Gorgeous photographs and great information Phil.

Murthy K v v s said...

So cute bird..!

Gillena Cox said...

your beautiful bird photos are such a delight

have a good Tuesday

much love...

Lowcarb team member said...

Thank you for your photo's and thank you for the information too. I am not a birder, as such, but do enjoy visiting your blog (and others) where I am beginning to learn and appreciate ...
That siskin you caught was an amazing weight.
Such lovely photo's I think my favourite has to be the Goldfinch.

Enjoy the remainder of today and have a good Wednesday tomorrow, I can't believe I'm writing Wednesday already (mid-week!!!)

All the best Jan

Modesto Viegas said...

Very good post!

eileeninmd said...

Hello, Phil, wonderful photos of all the birds. I guess it is ok for the birds to be fat. Happy Tuesday, enjoy your day!

Findlay Wilde said...

I have saved this blog post for my ringing notes, great information. thanks for sharing.

Adam Jones said...

Great post Phil. Siskins are great birds, and it's good to read some very good information about them.

Mary said...

Lovely captures! Our finches do not have the red face. It's very striking!

Jo said...

Hi Phil, such a pleasure for me to see your birds up-close. Your images are so sharp and clear. Thanks for sharing. Greetings, Jo

Chris Rohrer said...

Let's be clear here:) Fat is good for birds not so much for me:) I put the fat on and I can't get it off! We do the same thing with our hummers as they return on their migration. We check their fat content and some of them REALLY bulk up! Pretty amazing stuff.

Anu said...

Interesting text and great photos.

June Caedmon said...

I'm sorry about the Nuthatch. That is really interesting about the fat. Were you able to relate the increase in 2011 to anything specific? Like bad weather etc? Since it's happening again now, it would be interesting to see if there are any correlations. Happy birding!

K V V S MURTHY said...

Excellent photography...feathers looked so bright.

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