# Blue tit/great tit parents



## rottiepointerhouse (Feb 9, 2014)

We've got a couple of nesting boxes in our garden including one above our patio doors to the lounge/right under our bedroom window which are used by blue tits. Its lovely as we can sit and watch them come and go with food and hear the babies. Not so nice we often hear the woodpecker drilling on the box so we usually pop our head out and tell him to go away.

Anyhow the reason for my post - for the last two years and again this year we see blue tits start nesting in there, we hear the babies and see one blue tit and one great tit coming and going with food for them. 

Is it possible the blue and great tit are a breeding pair or is it more likely the great tit is just helping the blue tits out?


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## rona (Aug 18, 2011)

I would think it highly unlikely that thy are a pair. Interesting quirk of nature though. I'd be interested in if the next residents are Great tits 

Heterozygosity-based assortative mating in blue tits (Cyanistes caeruleus): implications for the evolution of mate choice


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## Phoenix24 (Apr 6, 2013)

It is highly unlikely they are a pair, but I suppose not impossible, as each species has been known to lay in the other's nest where there has been a nest site shortage (this is known as 'egg dumping') and the owners of the nest often will raise the young of the other, though the success rate is variable*. But a blue tit raised by a great tit, or vice versa, may identify with the other species as its own, and thus attempt to choose one as a mate. However, there are other barriers to interbreeding between species, of which song and plumage being the main two factors.

Even if a great tit and blue tit did pair up, if any eggs were produced they would likely be infertile. In the extremely unlikely event that the eggs hatched the hybrids would probably not survive, and would themselves be sterile anyway.

Equally unlikely (but also not impossible) is nest sharing by the two species, ie where one has egg dumped in the other's nest but not abandoned it or been driven away by its owners.

Are you absolutely certain both adults are bringing food (it is a bit early, by the way, and blue tits normally lay a week or so later than great tits), and not say... nest material? Or perhaps one is just looking for a nest site of its own and looking in the box?

Another possibility is that the begging cries of the chicks has attracted the attention of an unpaired adult, who has found them irresistible to ignore. This does happen, though normally with fledglings that pester any bird it sees for food.

*One summer in the nest boxes I monitor I had a blue tit build a nest over a pied flycatcher nest, but the pied flycatcher laid 2 eggs in it anyway, and the blue tit incubated and raised the 2 chicks with its own. Unfortunately the nest was abandoned before the chicks fledged - probably due to the death of one of the adults - but I will never know for sure, nor did I get to see the outcome of a rather interesting mixed nest. I have photos if you want to see them).

ETA: If you are having trouble with woodpeckers or anything else trying to get into the box, you can buy metal plates to protect the holes of the box. Get the 32mm size plate and not the smaller one which will only allow in blue tits.

http://shopping.rspb.org.uk/birds-wildlife/nestboxes/nestbox-plate-32mm.html


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## rottiepointerhouse (Feb 9, 2014)

Thanks for the replies.

We have 3 boxes on the back of our house but only one seems to be used which is the one above our lounge doors. We can see really well as the adult birds tend to perch on top of our gate before flying up to the nest box. Both the great and blue are taking food up and we've been able to hear the chicks for a couple of days now (we are on the south coast so quite mild). We are pretty sure this is the 3rd year this odd arrangement has taken place but sadly we have never seen the chicks leave the nest to know what they look like although my OH say when he cleaned the box out there was one dead chick in it which was a blue tit. 

I will try to take some photos if I can and yes please Phoenix 24 would love to see your photos.


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## jill3 (Feb 18, 2009)

Maybe next year get one of those camera that you can pop in the nest box.
I think Aldi were selling them.
Would be very interesting to see.
Also I think you can get a metal ring to put around the hole of the opening to stop squirrels and maybe stop the woodpecker from breaking in


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## Phoenix24 (Apr 6, 2013)

If you are able to open the box lid without disturbing the nest, please try to get a photo. Any chance you can get photographs of both species attending the box? This may take some patience, but if you sit still inside the adults will return every 10-20 mins and it would be very interesting to see what is going on with your nest. 

If you can get the lid open, peer in carefully to see what stage the chicks are at. Once the feathers start to emerge we can identify the species more easily than when they are still naked and blind (although great tit chicks are much larger than blue tits). If the chicks are very well grown, and hopping around inside the box, it will not be safe to take a photo. It takes approx 16 days for fledging, so any time up until 10 days it will be ok to open the lid for a photograph.

If you have one of those side opening boxes, be very careful but you might be able to slowly open it a little to take a look inside - if the chicks are still small enough you might be able to open the box enough for a picture (by small enough I mean still contained within the cup of the nest, and not hopping around looking like miniature adults).

Don't worry too much about the disturbance to the nest, I can assure you that once you have left it the adults will quickly return. But don't take more than 20 mins or so at the box, and please have a quick scan for any predators that might be watching before you do open the lid.

I will dig out some photos for you.


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## Phoenix24 (Apr 6, 2013)

The following two photos were taken a couple of days apart, and show two pied flycatcher chicks in with a brood of about 6 blue tits (if I remember correctly there were more blue tits, but as the pied flycatchers grew - which they do much faster and bigger - blue tits were unable to compete and some died).

















The next photo is a brood of blue tits ready to fledge (photo taken with great care I can assure you, something I wouldn't recommend you attempting).









And the last photo is a brood of great tits at about 8-9 days of age - lots of feathers but all still in the cup and safe to take a picture.









I have been monitoring nesting birds for the last 14 years and have quite a wealth of photographs, though nest box photos are extremely tricky because getting the focus and the light right can be a right pain!

If you want to know more about nest recording see

The Nest Record Scheme | BTO - British Trust for Ornithology


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## rottiepointerhouse (Feb 9, 2014)

Thank you those photos are amazing. 

I will do my best to get some photos although not sure about in the box as its quite high so OH has to get his ladders out.


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## Phoenix24 (Apr 6, 2013)

Thankfully nearly all my nest boxes are at head height, as carrying ladders around the hills of North Wales was a bit of a killer (I monitor around 90).

Hopefully you can open the box at the lid. I don't get why all the commercially made boxes are nigh on impossible to open safely/sensibly - nests should be cleaned out at the end of the season for hygiene after all, and a lid opening is much safer than a base or side! 

Anyway, lets see what pictures you can get - safely - I mean yours and the birds.


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## Valanita (Apr 13, 2010)

Phoenix24 said:


> The following two photos were taken a couple of days apart, and show two pied flycatcher chicks in with a brood of about 6 blue tits (if I remember correctly there were more blue tits, but as the pied flycatchers grew - which they do much faster and bigger - blue tits were unable to compete and some died).
> 
> View attachment 138045
> 
> ...


Wow! Amazing, the first photo's. I didn't think that ever happened.


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## Phoenix24 (Apr 6, 2013)

Yep. It surprised me too, as its more common between the tit species - but where I record nests the great tits typically are at least a week ahead of the blue tits and flycatchers, whereas those two species overlap in timing greatly.


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## rottiepointerhouse (Feb 9, 2014)

I haven't managed to get any photos sorry. My camera is not a good enough one and the few times I've seen both the blue and the great tit fly up to the box with food I've been too slow to get photos. I might have more luck when they leave the nest and must get myself a decent camera.


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## Phoenix24 (Apr 6, 2013)

Well do try if you can, we all want to know what babies come out of there in the least, or a pic of each species in attendance would be amazing. 

You can get nest box cameras for reasonable prices - ALDI are doing a kit for less than £40 at the moment, though I don't know if you can get stills from it.


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