Blue tit baby food

Question

Hi all, 
 We have some blue tits nesting in nest box for second year now. I've read that blue tit parents feed chicks on a very specific type of caterpillar. The parents are busy to-ing and fro-ing from the nest, but i noticed over the last week that one parent now comes to get some suet and fat balls i have out (if it gets a chance between the sparrows!), and then flies immediately back to the nest. It does this repeatedly as though it is feeding the chicks suet. 
 Just wondered if anyone else has seen this behaviour in blue tits, and if it might not be a good things for the chicks if they need the caterpillars? The other parent is also around and seems to go elsewhere. 
 Thanks 
 Neil

HAZY · Accepted Answer

Hello Neil, lovely to hear you have blue tit nestlings in your box. The growing youngsters need a lot of food each day (on average up to 100 bits of food per chick !) - which are mainly green caterpillars and other insect foods such as spiders that the parents will find around the outside of sheds, outbuildings, house, etc., They will also supplement their main caterpillar diet with foods we put out such as suet as the chicks start to grow - this is absolutely fine for them so don't worry. Their main diet is the green caterpillar (oak moth) as the parent birds try to coincide their breeding with the emergence of these caterpillars. 
 A lot of us on the forum also make plain pastry (especially during harsh winter months) with supermarket own brand plain flour (brown or white), lard or dripping, mixed together as you would for ordinary pastry except there is NO SALT added. You can add suet pellets or a little crushed seeds/kibbled peanuts (suitable for wildlife) to the mix and even a small amount of grated mild cheddar cheese; you bind the ingredients with just enough water to pull the pastry together so it is not sticky and can place it in your fat ball or fat cake feeders or even put little pieces on the twigs, shrubs around your garden and most of the birds will be happy to take it; this is also suitable for chicks. If you want to splurge out, depending on your budget, you can buy mealworms; fresh is the best and you can order these by post which come the next day via Royal Mail They are also available via the shop (homepage) on this RSPB website or you can use dried mealworms which are soaked first and try those which some birds will take. During these busy times for the adult birds it can help them by putting suitable foods out. Just remember not to put whole peanuts out unless they are in a dedicated peanut feeder as an inexperienced parent bird could inadvertently feed a nestling a whole nut which it could choke on. I am sure they don't do this but just to be on the safe side. 
 So keep the suet pellets going and enjoy watching from a distance those beautiful nestlings hatch from your nest-box ! Good luck.