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Trophic Niche in a Raptor Species: The Relationship between Diet Diversity, Habitat Diversity and Territory Quality.

Navarro-López J, Fargallo JA - PLoS ONE (2015)

Bottom Line: If true, foraging strategies should be associated with individual quality and fitness.Our results show that: 1) territory quality was quadratically correlated with habitat diversity, with the best territories being the least and most diverse; 2) diet diversity was not correlated with territory quality; and 3) diet diversity was negatively correlated with landscape heterogeneity.Our study suggests that niche generalist foraging strategies are based on an active search for different prey species within or between habitats rather than on the selection of territories with high habitat diversity.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Ecología Evolutiva, Museo Nacional de Ciencias Naturales-C.S.I.C., José Gutiérrez Abascal 2, 28006, Madrid, Spain.

ABSTRACT
Recent research reports that many populations of species showing a wide trophic niche (generalists) are made up of both generalist individuals and individuals with a narrow trophic niche (specialists), suggesting trophic specializations at an individual level. If true, foraging strategies should be associated with individual quality and fitness. Optimal foraging theory predicts that individuals will select the most favourable habitats for feeding. In addition, the "landscape heterogeneity hypothesis" predicts a higher number of species in more diverse landscapes. Thus, it can be predicted that individuals with a wider realized trophic niche should have foraging territories with greater habitat diversity, suggesting that foraging strategies, territory quality and habitat diversity are inter-correlated. This was tested for a population of common kestrels Falco tinnunculus. Diet diversity, territory occupancy (as a measure of territory quality) and habitat diversity of territories were measured over an 8-year period. Our results show that: 1) territory quality was quadratically correlated with habitat diversity, with the best territories being the least and most diverse; 2) diet diversity was not correlated with territory quality; and 3) diet diversity was negatively correlated with landscape heterogeneity. Our study suggests that niche generalist foraging strategies are based on an active search for different prey species within or between habitats rather than on the selection of territories with high habitat diversity.

No MeSH data available.


Quadratic relationship between nest box occupancy and territory landscape heterogeneity (Shannon-Wiener index of habitats) of common kestrels.
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pone.0128855.g002: Quadratic relationship between nest box occupancy and territory landscape heterogeneity (Shannon-Wiener index of habitats) of common kestrels.

Mentions: Dry pasture was the most widespread habitat in the study area (58.13%,) followed by oat pasture (22.12%, Fig 1 and S1 Table). These two habitats were also the most commonly found in the 1km-radius areas where nest boxes were installed (53.7% and 27.4% respectively; S1 Table). On average, habitat diversity in kestrel territories was 1.18 ± 0.08, ranging from 1.03 to 1.39. The LM exploring the relationship between occupancy and TLH showed a curvilinear correlation (TLH, F1,58 = 5.44, P = 0.023, TLH2, F1,58 = 5.54, P = 0.02; Fig 2). The highest occupancy was observed in the most and least diverse territories. When including in the model habitat PC1, habitat PC2 and breeding density as other potential explanatory variables, the best model obtained for this set of variables was the one containing the terms PC2, TLH and TLH2 (Table 3). Occupancy was significantly and negatively correlated with PC2 (Table 3), indicating that more frequently occupied territories were those with larger expanses of ungrazed and sandy pastures and shorter expanses of rocky lands and scrubland. In the selected model the effects of TLH and TLH2 were statistically reduced (Table 3). Occupancy was not significantly correlated with either breeding density or habitat PC1 (both P > 0.11).


Trophic Niche in a Raptor Species: The Relationship between Diet Diversity, Habitat Diversity and Territory Quality.

Navarro-López J, Fargallo JA - PLoS ONE (2015)

Quadratic relationship between nest box occupancy and territory landscape heterogeneity (Shannon-Wiener index of habitats) of common kestrels.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4457527&req=5

pone.0128855.g002: Quadratic relationship between nest box occupancy and territory landscape heterogeneity (Shannon-Wiener index of habitats) of common kestrels.
Mentions: Dry pasture was the most widespread habitat in the study area (58.13%,) followed by oat pasture (22.12%, Fig 1 and S1 Table). These two habitats were also the most commonly found in the 1km-radius areas where nest boxes were installed (53.7% and 27.4% respectively; S1 Table). On average, habitat diversity in kestrel territories was 1.18 ± 0.08, ranging from 1.03 to 1.39. The LM exploring the relationship between occupancy and TLH showed a curvilinear correlation (TLH, F1,58 = 5.44, P = 0.023, TLH2, F1,58 = 5.54, P = 0.02; Fig 2). The highest occupancy was observed in the most and least diverse territories. When including in the model habitat PC1, habitat PC2 and breeding density as other potential explanatory variables, the best model obtained for this set of variables was the one containing the terms PC2, TLH and TLH2 (Table 3). Occupancy was significantly and negatively correlated with PC2 (Table 3), indicating that more frequently occupied territories were those with larger expanses of ungrazed and sandy pastures and shorter expanses of rocky lands and scrubland. In the selected model the effects of TLH and TLH2 were statistically reduced (Table 3). Occupancy was not significantly correlated with either breeding density or habitat PC1 (both P > 0.11).

Bottom Line: If true, foraging strategies should be associated with individual quality and fitness.Our results show that: 1) territory quality was quadratically correlated with habitat diversity, with the best territories being the least and most diverse; 2) diet diversity was not correlated with territory quality; and 3) diet diversity was negatively correlated with landscape heterogeneity.Our study suggests that niche generalist foraging strategies are based on an active search for different prey species within or between habitats rather than on the selection of territories with high habitat diversity.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Ecología Evolutiva, Museo Nacional de Ciencias Naturales-C.S.I.C., José Gutiérrez Abascal 2, 28006, Madrid, Spain.

ABSTRACT
Recent research reports that many populations of species showing a wide trophic niche (generalists) are made up of both generalist individuals and individuals with a narrow trophic niche (specialists), suggesting trophic specializations at an individual level. If true, foraging strategies should be associated with individual quality and fitness. Optimal foraging theory predicts that individuals will select the most favourable habitats for feeding. In addition, the "landscape heterogeneity hypothesis" predicts a higher number of species in more diverse landscapes. Thus, it can be predicted that individuals with a wider realized trophic niche should have foraging territories with greater habitat diversity, suggesting that foraging strategies, territory quality and habitat diversity are inter-correlated. This was tested for a population of common kestrels Falco tinnunculus. Diet diversity, territory occupancy (as a measure of territory quality) and habitat diversity of territories were measured over an 8-year period. Our results show that: 1) territory quality was quadratically correlated with habitat diversity, with the best territories being the least and most diverse; 2) diet diversity was not correlated with territory quality; and 3) diet diversity was negatively correlated with landscape heterogeneity. Our study suggests that niche generalist foraging strategies are based on an active search for different prey species within or between habitats rather than on the selection of territories with high habitat diversity.

No MeSH data available.