Diseases Parasites – Long tailed Cuckoo Brown creepers are one of the main hosts for the long-tailed cuckoo in the South Island and Stewart Island and can sometimes be seen feeding a much larger cuckoo chick during the summer months. They can also be parasitised by shining cuckoos. Brown creepers have a high rate of rejection for long-tailed cuckoo eggs in their nests. This is due to the fact that brown creepers have an open nest as opposed to a closed or cavity nest. Having an open nest allows for more light to get in and increases the chance of the birds noticing a foreign egg. Despite all of this the long-tailed cuckoo is very host specific and chooses to mimic the eggs of brown creepers. Brown creepers have also been known to mob long-tailed cuckoos when they are present in spring and summer as a form of prevention. Mobbing is where individual birds produce warning calls, which the entire flock hears and responds to by surrounding the predator, with wings and tails erect whilst hopping between perches and calling until the predator moves away. Brown creepers have been observed mobbing cats, stoats, rats, larger birds, and even humans. European settlement Brown creeper numbers declined soon after European settlement due to the introduction of cats, rats and mustelids. The eggs and young of brown creepers are predated on mostly by stoats and black rats. Brown creeper number were also negatively affected but the loss of much of the important lowland forest. However their current distribution seems to have stabilized. Laughing owls have now been extinct since the 1930s/40s. It has been shown through fossil records of their food deposits that they would preyed on brown creepers. Other Information Use of UV light vision to recognize foreign eggs There has been some research done that may indicate the use of UV wavelength light in brown creepers ability to recognize long-tailed cuckoo eggs. Brown creepers are known to reject long-tailed cuckoo eggs whereas yellowheads and whiteheads, who are close relatives of brown creepers, tend not to. The research showed that both the brown creeper and yellowhead lacked a short-wavelength sensitive (SWS1) opsin gene which has large effects on the range of light that can be seen. This can influence how far in or out of the UV range an organism can see, which in terms of the Mohoua spp. (the Mohoua spp.