Haemosporidian parasites and leukocyte profiles of pre-migratory rosy starlings (Pastor roseus) brought into captivity

Abstract

Immune response to pathogens such as avian malaria (Plasmodium spp.) and related haemosporidian parasites (Haemoproteus spp. and Leucocytozoon spp.) can lead to increases in energy demands of birds. Migrations are energetically costly for birds and require resources that could be otherwise invested in immune defence against pathogens. Here, we examined the prevalence and intensity of haemosporidian parasites (Apicomplexa, Haemosporida) in rosy starlings (Pastor roseus), an irruptive migrant on the Balkans, during their pre-migratory period. We further evaluated if these infections affected the stress levels of birds brought into overnight captivity, using leukocyte profiles (ratios of heterophils to lymphocytes, or H/L ratios). Haemosporidian parasites were detected based on microscopic examination, PCR and sequencing. We found high prevalence of haemosporidian parasites (83.9%) in rosy starlings (n=31), with predominant infections of Haemoproteus pastoris (cytochrome b lineage LAMPUR01) (80.1%). All birds had high heterophil/lymphocyte ratios (mean = 3.86), indicating the transition to captivity was stressful. However, there was no added stress from blood parasite infection during captivity, since infected birds did not have significantly higher heterophil/lymphocyte ratios than uninfected birds, despite all birds facing the same stress conditions. There was a negative correlation between intensity of H. pastoris and monocyte proportions, which may indicate an association with infection, or an artefact of the stress-induced shift in leukocyte profile following captivity. Our findings suggest that blood parasites have minimal additional impact on rosy starlings during an acute stress scenario (overnight captivity), arguing that they carry little cost to the energetically challenging migratory flight.

Experimental study of newly described avian malaria parasite Plasmodium (Novyella) collidatum n. sp., genetic lineage pFANTAIL01 obtained from South Asian migrant bird

“…The transmission, apparently, takes place in these regions. Several records of pFANTAIL01 were reported in bird species breeding in Europe, Common rosefinch [ 18 ], Rosy starling [ 50 ] and in one of Milvus sp. [ 45 ].…”

Ecophysiological assessment of blood haemosporidian infections in birds

“…Algunos autores han descrito un efecto negativo de la infección por malaria en la condición física (ej. Norte et al 2009;Cloutier et al 2011), mientras que otros no han encontrado relación alguna (Krams et al 2013;Dimitrov et al 2019); aunque la ausencia de efectos podría explicarse por la falta de estudios longitudinales o la muerte selectiva de individuos que no superan la fase aguda de la infección. De un modo general, la pérdida de masa corporal derivada de la falta de ingesta o del consumo de recursos energéticos para compensar los daños ocasionados por los parásitos (como puede ser la activación de una respuesta inmune, reparación de un daño, etc.…”

Experimental study of newly described avian malaria parasite Plasmodium (Novyella) collidatum n. sp., genetic lineage pFANTAIL01 obtained from South Asian migrant bird

“…The transmission, apparently, takes place in these regions. Several records of pFANTAIL01 were reported in breeding bird species in Europe, Common rose nch [18] and Rosy starling [51] and in one of Milvus sp. [46].…”