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      FIG 20. With their fine bill, Siskins are one of the species to have taken to Niger seeds, though they seem to prefer sunflower hearts if these are available and there is little competition from larger species like Greenfinch. (John Harding)

      Fat and suet products

      Although highly variable in terms of their content, a high-quality fat product may have in excess of 8,500 kcal per kg, something that makes these products particularly attractive for use during the winter months. Fat- and suet-based products come in a diversity of forms, probably the most familiar of which are ‘fat balls’ and square or rectangular blocks. Fat balls almost always used to be sold within plastic mesh netting, something that was occasionally responsible for the death of a feeding bird, either caught by its foot or by its barbed tongue. Although a substantial number of netted fat balls are still sold (and purchased) within the UK market, there has been a welcome move towards un-netted fat balls.

      Suet may also be presented in a pelletised form, something that is popular with Starlings, or in or around objects such as plastic sticks or coconut shells – popular with Blue Tits and Great Tits. Suet products often contain additional material, perhaps added to increase the range of species that will take it, to broaden its nutritional composition or to secure a marketing advantage. These include seeds, nuts, berries and insect protein (typically mealworms). Suet products may also contain ash in variable quantities, added in order to bind the material together and to reduce the chances of the product breaking down. Again, the Bird Care Standards Association has a set of rules relating to this type of product, though these are geared more towards the source of the fat, rather than the composition of the product or content of additional material. The standards are as follows:

      i) suet should be derived from animals that have received ante- and post-mortem examination by veterinary officers and found to be fit for human consumption;

      ii) all suet should be processed at a fully licensed and approved EU or US abattoir, and

      iii) any suet products that are blended with peanuts, either in whole or granular form, must use peanuts that contain a nil detectable aflatoxin level.

      Live foods

      The term ‘live foods’ refers to the provision of insects, typically mealworms and wax worms, which are bred specifically for this and the wider pet food market. These may be provided alive or, more commonly, in a desiccated form. Mealworms are not worms but larvae of darkling beetles belonging to the genus Tenebrio. Within the UK it is the larvae of the Yellow Mealworm Tenebrio molitor that are most commonly used as food for wild and aviary birds, captive reptiles and amphibians. The smaller sized larvae of the Dark Mealworm Tenebrio obscura are sometimes used. As their name suggests, mealworms have a long association with human beings, occurring as pests of grain and other cereal products. Mealworms are fairly easy to rear, both at home and commercially, and a number of companies are now involved in the large-scale farming of these beetles, producing insect protein not just for wild birds and the pets already mentioned but also as a contribution to cat and dog food products and, looking to the future, human foods (Grau et al., 2017).

      FIG 21. Mealworms are often very popular with Starlings, Robins and Blackbirds, with individual birds quickly learning to exploit them where they are offered. (John Harding)

      Wild birds seem to prefer live mealworms, presumably because they attract attention by their movements, but probably because they are far closer in their composition to wild caught food. Mealworms have a high protein (13–22 per cent) and fat (9–20 per cent) content and are also a source of polyunsaturated fatty acids, essential amino acids and zinc. Perhaps surprisingly, they have a significantly higher nutritional value than either beef or chicken.

      Other foods

      Bread appears to be a popular food with householders, perhaps because it provides an opportunity for them to direct unwanted crusts or stale slices towards other creatures perceived to be in need of sustenance. Its nutritional value is, in the context of garden birds, unclear. Bread was by far the commonest food provided by householders who responded to a questionnaire survey carried out in Cardiff in the 1980s (Cowie & Hinsley, 1988a), with c. 90 per cent of respondents provisioning bread in both winter and summer. Galbraith et al. (2014) found bread to be the most commonly provisioned food in their study, estimating that the equivalent of more than five million loaves was put out by New Zealand residents annually.

      FIG 22. A small number of UK householders put out meat scraps or even whole carcasses for visiting Red Kites. (Jill Pakenham)

      Apart from the small number of householders nationally who provide meat for visiting Red Kites Milvus milvus, only a small proportion of the kitchen scraps fed to wild birds here in the UK include meat. The situation is very different in Australia where the provision of meat is fairly typical. This reflects clear differences between the main groups of birds visiting garden feeding stations here in the UK (seed-eating species) and in Australia (omnivorous species, such as Laughing Kookabura Dacelo novaeguineae, Australian Magpie Gymnorhina tibicen and Grey Butcherbird Cracticus torquatus). As we’ll see later in this chapter, the provision of meat has potential implications for wild bird health.

      In parts of North America, sugar solution is used to attract and feed hummingbirds. Typically made from one-part cane sugar to four-parts water, the solution is seen as a supplementary food rather than a replacement for the sugars that these tiny birds would normally secure from flowers. While those hummingbirds tested appear to be more strongly influenced by the position of a food source rather than

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