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Effect of Brood Age on Nestling Diet and Prey Composition in a Hedgerow Specialist Bird, the Barred Warbler Sylvia nisoria.

Orłowski G, Wuczyński A, Karg J - PLoS ONE (2015)

Bottom Line: The youngest nestlings (2-3 d old) had the lowest values of each dietary characteristic (diversity, number and total biomass of prey, and individual prey weight), that were significantly lower than the oldest nestlings (7-9 d old).Parent Barred Warblers probably preferentially select soft-bodied prey for the youngest nestlings, and satisfy the greater energy demands of the older ones by providing them with a greater variety of prey containing more chitin, as well as plant food.The provisioning of less-readily digestible prey to older nestlings suggests that as the quality of food decreases the quantity increases, implying that the youngest nestlings may be physiologically limited as regards their ability to digest more heavily chitinised prey.

View Article: PubMed Central - PubMed

Affiliation: Institute of Agricultural and Forest Environment, Polish Academy of Sciences, Poznań, Poland.

ABSTRACT
The composition and quality of food provided to nestling birds influence their growth and development and offers key insight into the ecological requirements of birds. One bird species whose feeding ecology is poorly understood is the Barred Warbler (Sylvia nisoria), which utilizes semi-natural shrubby vegetation in agroecosystems. Because Barred Warbler nestlings vary greatly in body mass we hypothesised that diet and prey properties (size, diversity, taxonomic composition, and chitin content and resulting body hardness and digestibility) would differ as the nestlings aged. We quantified the diet based on faecal analysis, sampling faecal sacs from the nestlings pooled into three age classes: 2-3 days old, 4-6 d old, and 7-9 d old. Nestlings were provided a wide diversity of food and a strong relationship existed between food characteristics and nestling age. The youngest nestlings (2-3 d old) had the lowest values of each dietary characteristic (diversity, number and total biomass of prey, and individual prey weight), that were significantly lower than the oldest nestlings (7-9 d old). Nestlings aged 4-6 d exhibited intermediate dietary characteristics. Differences in dietary composition of the six major food types showed marked differences between the individual broods and age categories. Percentages of the number and biomass of soft-bodied prey were highest in the diet of 2-3 d and 4-6 d old nestlings, and decreased with increasing age, whereas the opposite trend was observed in the percentage of intermediately and heavily chitinised prey. Parent Barred Warblers probably preferentially select soft-bodied prey for the youngest nestlings, and satisfy the greater energy demands of the older ones by providing them with a greater variety of prey containing more chitin, as well as plant food. The provisioning of less-readily digestible prey to older nestlings suggests that as the quality of food decreases the quantity increases, implying that the youngest nestlings may be physiologically limited as regards their ability to digest more heavily chitinised prey.

No MeSH data available.


Related in: MedlinePlus

The main dietary characteristics (average ± SE) of nestling Barred Warblers Sylvia nisoria in three age classes.The various letters indicate statistically significant differences obtained in the post-hoc comparison with ANOVA or ANOVA Kruskal-Wallis (see Results section for details).
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pone.0131100.g001: The main dietary characteristics (average ± SE) of nestling Barred Warblers Sylvia nisoria in three age classes.The various letters indicate statistically significant differences obtained in the post-hoc comparison with ANOVA or ANOVA Kruskal-Wallis (see Results section for details).

Mentions: The four main dietary characteristics calculated for individual faecal sacs showed statistically significant differences associated with brood identity and nestling age: diet diversity expressed as the number of prey taxa, the number of prey items, the total biomass of prey (Table 2) and individual prey weight (calculated for the entire set of prey items) (ANOVA Kruskal-Wallis, H2,661 = 13.0, P = 0.015) (Fig 1). In most cases the youngest, 2–3 d old nestlings showed the lowest values of each dietary characteristic, which were significantly lower compared to 7–9 d old nestlings. The most pronounced differences were found for the total biomass of prey, which was nearly 6-fold higher in the oldest nestlings than in the youngest ones. Further, dietary diversity and number of prey in faecal sacs of 2–3 d old nestlings were approximately two-fold lower compared to the oldest ones. Nestlings aged 4–6 d displayed a relatively intermediate dietary characteristics. Exact patterns of between-group differences are presented in Fig 1.


Effect of Brood Age on Nestling Diet and Prey Composition in a Hedgerow Specialist Bird, the Barred Warbler Sylvia nisoria.

Orłowski G, Wuczyński A, Karg J - PLoS ONE (2015)

The main dietary characteristics (average ± SE) of nestling Barred Warblers Sylvia nisoria in three age classes.The various letters indicate statistically significant differences obtained in the post-hoc comparison with ANOVA or ANOVA Kruskal-Wallis (see Results section for details).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4482603&req=5

pone.0131100.g001: The main dietary characteristics (average ± SE) of nestling Barred Warblers Sylvia nisoria in three age classes.The various letters indicate statistically significant differences obtained in the post-hoc comparison with ANOVA or ANOVA Kruskal-Wallis (see Results section for details).
Mentions: The four main dietary characteristics calculated for individual faecal sacs showed statistically significant differences associated with brood identity and nestling age: diet diversity expressed as the number of prey taxa, the number of prey items, the total biomass of prey (Table 2) and individual prey weight (calculated for the entire set of prey items) (ANOVA Kruskal-Wallis, H2,661 = 13.0, P = 0.015) (Fig 1). In most cases the youngest, 2–3 d old nestlings showed the lowest values of each dietary characteristic, which were significantly lower compared to 7–9 d old nestlings. The most pronounced differences were found for the total biomass of prey, which was nearly 6-fold higher in the oldest nestlings than in the youngest ones. Further, dietary diversity and number of prey in faecal sacs of 2–3 d old nestlings were approximately two-fold lower compared to the oldest ones. Nestlings aged 4–6 d displayed a relatively intermediate dietary characteristics. Exact patterns of between-group differences are presented in Fig 1.

Bottom Line: The youngest nestlings (2-3 d old) had the lowest values of each dietary characteristic (diversity, number and total biomass of prey, and individual prey weight), that were significantly lower than the oldest nestlings (7-9 d old).Parent Barred Warblers probably preferentially select soft-bodied prey for the youngest nestlings, and satisfy the greater energy demands of the older ones by providing them with a greater variety of prey containing more chitin, as well as plant food.The provisioning of less-readily digestible prey to older nestlings suggests that as the quality of food decreases the quantity increases, implying that the youngest nestlings may be physiologically limited as regards their ability to digest more heavily chitinised prey.

View Article: PubMed Central - PubMed

Affiliation: Institute of Agricultural and Forest Environment, Polish Academy of Sciences, Poznań, Poland.

ABSTRACT
The composition and quality of food provided to nestling birds influence their growth and development and offers key insight into the ecological requirements of birds. One bird species whose feeding ecology is poorly understood is the Barred Warbler (Sylvia nisoria), which utilizes semi-natural shrubby vegetation in agroecosystems. Because Barred Warbler nestlings vary greatly in body mass we hypothesised that diet and prey properties (size, diversity, taxonomic composition, and chitin content and resulting body hardness and digestibility) would differ as the nestlings aged. We quantified the diet based on faecal analysis, sampling faecal sacs from the nestlings pooled into three age classes: 2-3 days old, 4-6 d old, and 7-9 d old. Nestlings were provided a wide diversity of food and a strong relationship existed between food characteristics and nestling age. The youngest nestlings (2-3 d old) had the lowest values of each dietary characteristic (diversity, number and total biomass of prey, and individual prey weight), that were significantly lower than the oldest nestlings (7-9 d old). Nestlings aged 4-6 d exhibited intermediate dietary characteristics. Differences in dietary composition of the six major food types showed marked differences between the individual broods and age categories. Percentages of the number and biomass of soft-bodied prey were highest in the diet of 2-3 d and 4-6 d old nestlings, and decreased with increasing age, whereas the opposite trend was observed in the percentage of intermediately and heavily chitinised prey. Parent Barred Warblers probably preferentially select soft-bodied prey for the youngest nestlings, and satisfy the greater energy demands of the older ones by providing them with a greater variety of prey containing more chitin, as well as plant food. The provisioning of less-readily digestible prey to older nestlings suggests that as the quality of food decreases the quantity increases, implying that the youngest nestlings may be physiologically limited as regards their ability to digest more heavily chitinised prey.

No MeSH data available.


Related in: MedlinePlus