Editing Welcome swallow (section)

==Predators, parasites and diseases==
The hawk, snake and feral cat are the main predators that hunt welcome swallows.<ref name=" Oliver ">{{cite book |last1= Oliver |first1= L |last2= Austin |first2= J.I. |last3= Arthur |first3= S |year=1962 |title= Birds of the World|pages=216–218}}</ref> Especially in Australia, snakes are the most dangerous predator for the birds. Snakes can climb trees to reach the nests and eat the eggs or young birds. According to one New Zealand study, the only time a nest failed was from disturbing the nest during the incubation period; these instances were from humans, mammals such as mustelids, and blackbirds preying upon the eggs.<ref name="Tarburton"/> In swallows' excreta, there are various kinds of bacteria and parasites,<ref name=Higgins/> which breed in the nest and cause very severe diseases; for example, histoplasmosis, encephalitis, salmonella, meningitis and toxoplasmosis. Hatchlings depend on maternal antibodies and immunity provided by the yolk sac within the egg.<ref name=" Sindik ">{{cite journal |last1= Sindik |first1=L |last2= Lill |first2= A |year=2009 |title= Peripheral Blood Leukocyte Counts in Welcome Swallow Nestlings |journal= Journal of Wildlife Diseases |volume=45 | issue = 4  |pages=1203–1207 |doi=10.7589/0090-3558-45.4.1203|pmid=19901398 |doi-access= free }}</ref> Although no specific parasites were found, welcome swallows are known as colonial breeders and are at a high risk for parasites, which may be a cause of lower breeding success but an increase in immune responsiveness.<ref name=" Sindik "/> Another disease that not only affects the poultry business, but also the welcome swallow is fowlpox.<ref name="Diallo">{{cite journal |last1=Diallo |first1=I.S |last2=MacKenzie |first2=M.A |last3=Spradbrow |first3=P.B |last4=Robinson |first4=W.F |year=1998 |title= Field Isolates of the Fowlpox Virus contaminated with the Reticuloendotheliosis Virus |journal= Avian Pathology |volume=27 |issue=1 |pages=60–66 |doi=10.1080/03079459808419275|pmid=18483965 |doi-access= }}</ref> This virus has two forms, cutaneous (mild harm) and diphtheritic (deadly); poultry is usually vaccinated for the virus, but wildlife is not.<ref name="Diallo"/>