Summary of the status of population health indices within species

Summaries below exclude the current year (2020) as this dataset is incomplete. When referring to demographic groups within the population, we mean the age and sex of the birds.


Demographic ratios (age and sex) within sparrowhawks received by the PBMS remain within the 95% prediction intervals (95%PI) established in baseline years (2000 to 2016). This means there has not been a significant change in the demographic structure of the sparrowhawks received by the PBMS.

Body weight, putative cause of death, fat score, and condition index were within predicted range for all the demographic groups analysed. This indicates that the nutritional status of the sparrowhawks received by the PBMS was consistent through baseline years and has not significantly changed from that baseline in subsequent years. N.B. There were insufficient male adult sparrowhawks received each year to calculate a baseline. These observations indicate that food availability has been consistent through both baseline years and since 2017.

Fluctuating asymmetry in the 10th primary feather weight (FAP10) within adults (females and males combined) between 2017 and 2019 remained generally consistent, with no time trend evident, and within the prediction range. 2019 juvenile female birds had showed higher average FAP10 than baseline years. Male juvenile birds showed an increase in FAP10 in baseline years, and from 2017 to 2019 data were consistent with this trend. Increases in FAP10 may indicate that birds have been subject to physiological stress during the development of flight feathers. Our observations indicate that juveniles (particularly male) may be subject to increasing levels of physiological stress during feather flight development (i.e. during the fledging period).

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