Studies on the Sexual Cycle in Birds. V. Effects of Light of Different Intensities upon the Testis Activity of the European Starling (Sturnus vulgaris)

1931 ◽  
Vol 4 (4) ◽  
pp. 542-574 ◽  
Author(s):  
Thomas Hume Bissonnette
Keyword(s):  
Sturnus Vulgaris ◽  
European Starling ◽  
Sexual Cycle

Effects of an introduced, novel prey on diet and reproduction in the diet-specialist European Starling (Sturnus vulgaris)

2019 ◽  
Vol 97 (3) ◽  
pp. 225-231
Author(s):  
T.D. Williams ◽  
A. Cornell ◽  
C. Gillespie ◽  
A. Hura ◽  
M. Serota
Keyword(s):  
Prey Item ◽  
Brood Size ◽  
Natural Experiment ◽  
Prey Species ◽  
Sturnus Vulgaris ◽  
European Starling ◽  
Tarsus Length ◽  
Negative Effects ◽  
Diet Specialization ◽  
Specialized Diet

Diet specialization has important consequences for how individuals or species deal with environmental change that causes changes in availability of prey species. We took advantage of a “natural experiment” — establishment of a commercial insect farm — that introduced a novel prey item, black soldier flies (Hermetia illucens (Linnaeus, 1758)), to the diet-specialist European Starling (Sturnus vulgaris Linnaeus, 1758). We investigated evidence for individual diet specialization (IDS) and the consequences of diet specialization and exploitation of novel prey on breeding productivity. In all 4 years of our study, tipulid larvae were the most common prey item. Soldier flies were not recorded in diets in 2013–2014; however, coincident with the establishment of the commercial insect farming operation, they comprised 22% and 30% of all prey items in the diets of European Starling females and males, respectively, in 2015. There was marked individual variation in use of soldier flies (4%–48% and 2%–70% in females and males, respectively), but we found little evidence of dichotomous IDS, i.e., where only some individuals have a specialized diet. We found no evidence for negative effects of use of soldier flies on breeding productivity: brood size at fledging and chick quality (mass, tarsus length) were independent of the number and proportion (%) of soldier flies returned to the nest.

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