two decades. In 2009, great tits were reported killing, and eating the brains of roosting pipistrelle bats. This is the first time a songbird has been recorded preying on bats. The tits only do this during winter when the bats are hibernating and other food is scarce. They have also been recorded using tools, using a conifer needle in the bill to extract larvae from a hole in a tree. Breeding Great tits are monogamous breeders and establish breeding territories. These territories are established in late January and defence begins in late winter or early spring. Territories are usually reoccupied in successive years, even if one of the pair dies, so long as the brood is raised successfully. Females are likely to disperse to new territories if their nest is predated the previous year. If the pair divorces for some reason then the birds will disperse, with females travelling further than males to establish new territories. Although the great tit is socially monogamous, extra-pair copulations are frequent. One study in Germany found that 40% of nests contained some offspring fathered by parents other than the breeding male and that 8.5% of all chicks were the result of cuckoldry. Adult males tend to have a higher reproductive success compared to sub-adults. Great tits are seasonal breeders. The exact timing of breeding varies by a number of factors, most importantly location. Most breeding occurs between January and September; in Europe the breeding season usually begins after March. In Israel there are exceptional records of breeding during the months of October to December. The amount of sunlight and daytime temperatures will also affect breeding timing. One study found a strong correlation between the timing of laying and the peak abundance of caterpillar prey, which is in turn correlated to temperature. On an individual level, younger females tend to start laying later than older females. Great tits are cavity nesters, breeding in a hole that is usually inside a tree, although occasionally in a wall or rock face, and they will readily take to nest boxes. The nest inside the cavity is built by the female, and is made of plant fibres, grasses, moss, hair, wool and feathers. The number in the clutch is often very large, as many as 18, but five to twelve is more common. Clutch size is smaller when birds start laying later, and is also lower when the density