Malaria infection negatively affects feather growth rate in the house sparrowPasser domesticus

Abstract

Birds often face various stressors during feather renewing, for example, enduring infection with blood parasites. Because nutritional resources are typically limited, especially for wild animals, when an individual allocates energy to one physiological system, there is subsequently less for other processes, thereby requiring a trade‐off. Surprisingly, potential trade‐offs between malaria infection and feather growth rate have not been experimentally considered yet. Here, we conducted three studies to investigate whether a trade‐off occurs among feather growth rate, malaria infection and host health conditions. First, we explored whether naturally infected and uninfected house sparrows differed in feather growth rate in the wild. Second, we asked whether experimental inoculation of malaria parasites and/or forcing the renewal of a tail feather. Lastly, we evaluated whether individual condition was affected by experimentally‐induced feather regrowth and/or malaria experimental infection. Our findings showed that feather growth rate was negatively affected by natural malaria infection status in free‐living birds and by experimental infection in captive birds. Furthermore, birds that did not increase body mass or hematocrit during the experimental study had slower feather growth. Together our results suggest that infection with blood parasites has more negative health effects than the growth of tail feathers and that these two processes (response to blood parasite infection and renewal of feathers) are traded‐off against each other. As such, our results highlight the role of malaria parasites as a potential mechanism driving other trade‐offs in wild passerines.

Haemosporidian parasites depress breeding success and plumage coloration in female barn swallowsHirundo rustica

“…This result should be therefore considered with this caveat in mind. The finding of a reduction of feather growth rate in birds infected by haemosporidians is consistent with the few previous studies investigating this relationship (Marzal et al 2013a, b, Coon et al 2016 and shows that haemosporidian infection can impair a major life-history event, moult, with potentially severe negative consequences for feather morphology, and thus flight performance. The reason why such effect was detected only for older individuals is open to speculation.…”

“…We expected that infection affected feather growth rate because this effect has been shown in the few studies where it has been investigated so far (Marzal et al 2013a, b, Coon et al 2016) and malarial infection has been shown to affect the progress of moult (Morales et al 2007, Tarello 2007, but see Allander and Sundberg 1997). The rate of growth of the feathers during moult is sensitive to physiological state of the birds, and poor body conditions are reflected in reduced growth rate (Yosef andGrubb 1992, Takaki et al 2001).…”

“…Haemosporidian infection has been claimed to influence the progress of moult (Morales et al 2007, Tarello 2007, but see Allander and Sundberg 1997). There is also circumstantial evidence from previous studies of a passerine bird that haemosporidian infection can reduce feather growth rate (Marzal et al 2013a, b, Coon et al 2016. Feather growth rate can be inferred by the observation of feather growth bars (Grubb 1989, Saino et al 2012.…”

The relationship between blood parasites and ornamentation depends on the level of analysis in the common yellowthroat

“…Parasitism may also affect the condition of birds and, hence, the rate at which they grow new feathers (Coon et al ). To measure feather growth rate, we plucked the third tail feather (R3), counting inward from the outermost right tail feather, and estimated feather growth rate by measuring the average growth bar width on each tail feather.…”

Haemosporidian prevalence in northern saw‐whet owls Aegolius acadicus is predicted by host age and average annual temperature at breeding grounds

“…For example, several studies have found no deleterious effects of haemosporidian infection on reproductive fitness (Dufva 1996, Bensch et al 2007 or body condition (Ashford 1971, Dufva 1996, Young and Proudfoot 2014, and Zylberberg et al (2015) report a positive correlation of haemosporidian infection on fitness. In contrast, numerous studies have demonstrated that haemosporidian infection can have a negative effect on reproduction (Allander and Bennett 1995, Merino et al 2000, Knowles et al 2010, Asghar et al 2011, feather growth rate (Marzal et al 2013, Coon et al 2016, body condition (Dawson andBortolotti 2000, Marzal et al 2013), telomere-length (Asghar et al 2015), and can cause anemia and death (Valkiūnas 2005, Atkinson and Samuel 2010, Santiago-Alarcon et al 2013). Because of their effects on red blood cells, haemosporidians may have more subtle impacts on fitness via mechanisms such as inhibiting or delaying migration (Valkiūnas 1989, Asghar et al 2011.…”