Abstract
BackgroundInvestigating the ecological factors and processes shaping nest survival is of great importance for assessing the breeding success of bird populations and understanding their spatio-temporal dynamics. Here, this question is addressed for the Laughing Dove (Spilopelia senegalensis), an expanding Afro-tropical bird in the Tunisian oasis habitat.MethodsThis study took place in Kettana oasis, in south-eastern Tunisia. Natural Laughing Dove nests were searched for and monitored by means of regular visits, from the discovery date until the end of the breeding attempt (i.e. fledging or failure). Data were then used to investigate the relevance of laying date, nest age (days after clutch initiation), nest height and vegetation structure in the close nest tree environment as predictors of daily nest survival rate, using logistic-exposure models that accounted for heterogeneity in monitoring period among the studied nests. Models including different combinations of covariates were ranked according to their AICc scores, and the model-averaging technique was used for the assessment of the effects of covariates on daily nest survival rate.ResultsVegetation structure in the close nest tree environment and nest age provided important predictors of daily nest survival rate, whereas neither nest height nor laying date showed significant effects. Daily nest survival rate was negatively associated with the presence of date palm trees in the close nest tree environment, but it was positively related to nest age. Daily nest survival rate was higher during the post-hatching stage than during the pre-hatching stage.ConclusionsNests placed on fruit trees close to clumps of palm trees suffered higher predation risks compared to those placed on fruit trees situated far from palm trees. This is probably because palm tree clumps provided refuges for nest predators, notably the Black Rat (Rattus rattus) which has been reported to be the main nest predator in the oasis habitat. The predatory activity of this rodent seemed more directed against eggs than nestlings, which may explain the observed increase in daily survival rate with nest age.
Highlights
Investigating the ecological factors and processes shaping nest survival is of great importance for assessing the breeding success of bird populations and understanding their spatio-temporal dynamics
With regard to vegetation structure around the nest tree, the principal component analysis (PCA) conducted on the three assessed vegetation variables summarized them into one factor providing a composite index of vegetation structure at the close nest environment
The index of vegetation structure derived from the PCA was positively correlated with the covers of palm trees (r = 0.58, p < 0.0001) and herbaceous plants (r = 0.69, p < 0.0001) and negatively correlated with the cover of fruit trees (r = − 0.78, p < 0.0001)
Summary
Investigating the ecological factors and processes shaping nest survival is of great importance for assessing the breeding success of bird populations and understanding their spatio-temporal dynamics. This question is addressed for the Laughing Dove (Spilopelia senegalensis), an expanding Afro-tropical bird in the Tunisian oasis habitat. Investigating the relative importance of these factors in shaping nest survival is of great importance for assessing the breeding success of bird populations and for understanding their spatiotemporal dynamics. The breeding ecology of this expanding Afro-tropical bird in the Tunisian oasis habitat has previously been described by Boukhriss and Selmi (2009) who reported a modal clutch size of two eggs (more than 95% of studied clutches) and an estimated chick productivity of one chick per breeding attempt. The key factors affecting nest survival have not been investigated
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