Supplementary feeding increases nest size and egg size in black-billed magpies Pica pica in mixed agricultural habitats in southern Spain

  • Published source details De Neve L., Soler J.J., Ruiz-Rodriguez M., Martin-Galvez D., Perez-Contreras T.A.S. & Soler M. (2007) Habitat-specific effects of a food supplementation experiment on immunocompetence in Eurasian Magpie Pica pica nestlings. Ibis, 149, 763-773


This study is summarised as evidence for the following.

Action Category

Provide supplementary food for songbirds to increase reproductive success

Action Link
Bird Conservation
  1. Provide supplementary food for songbirds to increase reproductive success

    A replicated, controlled trial in habitats in southern Spain in 2001 (De Neve et al. 2007), found that black-billed magpie Pica pica nestlings provided with supplementary food had significantly higher cell-mediated immune responses (CMI, the change in swelling around insect bites, a measure of immunocompetence) in arid scrub, but not in irrigated farmland and woodland (arid scrub: average CMI of approximately 1.18 mm for fed nestlings vs. 0.85 m for controls; irrigated farmland/woodland: average CMI of 1.20 mm for fed nestlings vs. 1.18 mm for controls; 58 nests studied). In addition, fed nestlings showed significantly lower levels of the ectoparasite Carnus haemapterus (Diptera: Carnidae), but only in arid habitats (arid scrub: average infestation intensity of 0.40 arbitrary units for fed nestlings vs. 0.90 arbitrary units for controls; irrigated farmland/woodland: average 1.60 arbitrary units for fed nestlings vs. 1.65 arbitrary units for controls; 28 nests). Feeding had no effect on chick growth, weight or on the prevalence of blood parasites. Supplementary feeding consisted of 0.1 ml of high-calorie, nutrient-rich paste provided every other day for a total of 14 days.


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