Songbird nestlings tend to be helpless and dependent on the food their parents bring while they are confined to the nest. This means the nestling must get both nutrition and water from the food, and water is available in insect-based food but not in seeds and nuts. The diet of house sparrow nestlings, for instance, is insectivorous, although the adults feed on seeds and grain.
Most of the food that householders put out for birds does not contain a lot of water. Fortunately birds time their breeding to coincide with the springtime abundance of insects and bugs. However, there is one type of food commercially available that does contain water and is readily adopted by breeding birds feeding their young - mealworms. Mealworms are the larva of the darkling beetle, Tenebrio molitor. They can be bought either as live food or dried, and are often used for feeding reptiles as well as breeding birds so they can be bought at pet shops catering for reptile owners.
Though the term mealworms may put some people off, they are dry and not particularly smelly, although they do have a distinctive smell, which is stronger in warm weather. The smell is enough that it is desirable to keep live mealworms in outbuildings.
Mealworms are a treat for many birds, so if the intention is to target the smaller songbirds rather than bigger birds like Starlings, then a cage-type mealworm feeder can be used to target the smaller species like Robins, Blue Tits, Great Tits and House Sparrows. Members of the tit family feed their young on caterpillars. Blue Tits have a single large brood of about 10 chicks and are very dependent on the availability of caterpillars. If the spring is wet, such as the UK spring of 2007, this impacts breeding performance very seriously, and a supply of mealworms during long rainy spells in the breeding season can improve survival rates dramatically.
If there is no reason to target the smaller birds then a simple straight-sided container can be used for feeding mealworms to larger birds like blackbirds as well as most small birds. The straight sides help prevent live mealworms escaping. See the pictures attached to this article for an example of a cage-type feeder.
Any type of feeder should be located near mid-level bushy cover for the birds to escape, but away from the sort of low cover that can be occupied by waiting cats.
Live mealworms can be bought from local pet shops catering for reptile owners or online - they are not particularly messy so the can be sent via courier firms. They are usually supplied with a small amount of food like bran, which is enough to keep them until they are fed to the birds. The keenest prices on mealworms tend to be found online, usually from suppliers that specialise in mealworms and insects for the reptile trade rather than general bird food suppliers.
One of the advantages of mealworms is that they contain water. Thus dried mealworms on their own lose one of the main advantages, but rehydrating them easily rectifies this. This is not always stated on the packet! Leave them is warm water for a few minutes, then feed as if they were live, they will have most of the goodness of live mealworms without the ugh factor, while still letting the adult birds bring water to their nestlings.
Breeding Mealworms to Save Money
For the more adventurous, it is possible to raise mealworms and propagate them. This is much cheaper than buying them as they ingredients are very cheap - basically porridge oats and occasional pieces of carrots or celery. However, it takes a few months to get a culture of mealworms going
Although more awkward than seed, mealworms live or rehydrated are a rewarding way to help backyard birds during the stress of the breeding season, and you will soon enjoy a flurry of feathered visitors carrying off worms for small hungry beaks.