Health status of free-ranging ring-necked pheasant chicks (Phasianus colchicus) in North-Western Germany

Abstract

Being a typical ground-breeding bird of the agricultural landscape in Germany, the pheasant has experienced a strong and persistent population decline with a hitherto unexplained cause. Contributing factors to the ongoing negative trend, such as the effects of pesticides, diseases, predation, increase in traffic and reduced fallow periods, are currently being controversially discussed. In the present study, 62 free-ranging pheasant chicks were caught within a two-year period in three federal states of Germany; Lower Saxony, North Rhine-Westphalia and Schleswig-Holstein. The pheasant chicks were divided into three age groups to detect differences in their development and physical constitution. In addition, pathomorphological, parasitological, virological, bacteriological and toxicological investigations were performed. The younger chicks were emaciated, while the older chicks were of moderate to good nutritional status. However, the latter age group was limited to a maximum of three chicks per hen, while the youngest age class comprised up to ten chicks. The majority of chicks suffered from dermatitis of the periocular and caudal region of the head (57-94%) of unknown origin. In addition, intestinal enteritis (100%), pneumonia (26%), hepatitis (24%), perineuritis (6%), tracheitis (24%), muscle degeneration (1%) and myositis (1%) were found. In 78% of the cases, various Mycoplasma spp. were isolated. Mycoplasma gallisepticum (MG) was not detected using an MG-specific PCR. Parasitic infections included Philopteridae (55%), Coccidia (48%), Heterakis/Ascaridia spp. (8%) and Syngamus trachea (13%). A total of 8% of the chicks were Avian metapneumovirus (AMPV) positive using RT-PCR, 16% positive for infectious bronchitis virus (IBV) using RT-PCR, and 2% positive for haemorrhagic enteritis virus (HEV) using PCR. All samples tested for avian encephalomyelitis virus (AEV), infectious bursal disease virus (IBDV) or infectious laryngotracheitis virus

Occurrence and relevance of Mycoplasma spp. in free-ranging pheasants from northwestern Germany

“…As a higher percentage of the investigated chicks showed alterations associated with the detection of mycoplasmas in the periorbital skin (53.3%) compared to the investigated adult pheasants (13.8%), an age-dependency seems possible. As an immunosuppression of pheasant chicks due to a deficient protein uptake via nourishment was confirmed recently (Liebing et al 2020), a higher percentage of Mycoplasmapositive chicks showing periorbital skin alteration would support the theory of an involvement of the isolated Mycoplasma spp. as facultative pathogens.…”

“…As this bird species underlies the German Hunting Law, hunting bag statistics go back over several centuries showing a massive decline in the population since its plateau between 1960 and 1970 (Gehle 2011). Previous studies focused on potential infectious and non-infectious causes for this decline (Curland et al 2018;Liebing et al 2020) as well as on potential contributory factors (e.g., pesticides, predation, increasing traffic, changes in agricultural landscape) (Aebischer 1997;Moreby and Southway 1999). Thereby, it was shown that there is rather not a single pathogen but several factors contributing to the decline of pheasants in Germany, e.g., a reduced supply on protein-rich diet (e.g., insects) for pheasant chicks resulting in immunosuppression (Curland et al 2018;Liebing et al 2020).…”

“…Differential causes for periorbital skin alterations include ectoparasites, allergic reactions, and/or irritation by toxic agents (e.g., pesticides (Pass 1989)) or immunosuppression associated with secondary bacterial infections (Huff et al 2013;Thachil et al 2014). Furthermore, a contribution of infectious bronchitis virus (IBV) in the formation of skin alterations in the head region was discussed in prior studies (Liebing et al 2020). Furthermore, the time being caught in the live traps may lead to injuries especially at the bird's head due to escape reflex.…”

Review a brief history of coronaviruses in Thailand

“…The virus is present worldwide and causes significant economic losses ( Cavanagh, 2007 ). In addition, some studies have suggested that pheasants may also be susceptible to this virus ( Liebing et al, 2020 ). In Thailand infectious bronchitis in chickens was first reported in 1962 ( Chindavanig, 1962 ), and outbreaks have occurred continuously since that time ( Antarasena et al, 1990 ; Munyahongse et al, 2020 ; Pohuang et al, 2009 , 2011 ; Promkuntod et al, 2015 ; Upatoom et al, 1983 ) despite the use of vaccination, possibly due to strain specific vaccine breakthrough ( Jordan, 2017 ).…”

The modulating effect of food composition on the immune system in growing ring-necked pheasants (Phasianus colchicus)

“…For several years, a persistent decline of ring-necked pheasants was observed in northwestern Germany [ 3 ]. Previous studies on the health status of wild pheasants showed that a large proportion of chicks carry various parasites and pathogens, with especially the young chicks being of low nutritional status [ 4 ]. The population achieved a maximum in between 1960 and 1970 and in this period, the hunting bag enfolded about 300.000 pheasants in Lower Saxony [ 5 ].…”