Data and code from: Complex effects of ectoparasites on avian fitness: A meta-analysis
Data files
Sep 21, 2026 version files 222.55 KB
Abstract
Ectoparasites temporarily or permanently feed on their hosts and, hence, they are expected to exert a direct or indirect negative impact on host condition and fitness. Here, we conducted a meta-analysis to examine the effects of ectoparasites on fitness-related traits of avian hosts. We compiled ~850 effect sizes from available literature reflecting interactions of diverse ectoparasite taxa with a broad spectrum of avian hosts distributed worldwide. We found evidence for complex and multifaceted negative effects of ectoparasites on bird fitness. Host condition-related traits (e.g., haematology) were more strongly affected by ectoparasites compared to key fitness components, likely reflecting direct impact of ectoparasites on avian condition and health. In contrast, the effects of ectoparasites on avian survival and reproduction showed much greater heterogeneity, supporting strong stochasticity of associations between ectoparasitic pressure and fitness components. Finally, we found conspicuous variation in the impact of different ectoparasite groups on avian fitness, where mites, hemipteran bugs, and blowfly larvae yielded the strongest negative effects, whereas ticks, fleas, and chewing lice showed the weakest effects. We suggest that this variation may likely be driven by key life history traits and life cycles of ectoparasites. Our study builds a comprehensive framework for further ecological research on host-ectoparasite interactions, and it lays the foundation for a broader understanding of evolutionary responses of hosts to ectoparasite-mediated selection. We also identify major gaps in our knowledge and recommend that future scientific effort focus on enhancing (the still limited) diversity of the host-ectoparasite systems under study.
Description of the data and file structure
The data and code were deposited in three files:
- The file Complex_effects_of_ectoparasites_on_avian_fitness_RAW_DATA.xlsx contains three spreadsheets:
Raw_data spreadsheet contains data used in the meta-analysis (n = 852 effect sizes retrieved from 168 studies)
- species: species scientific name;
- host_age: age of the host classified as either nestling or adult;
- nest_type: nest type of the host classified as either cavity (tree cavities and nest boxes, rock cavities, crevices, and burrows) or non-cavity;
- log_body_mass: log-transformed species-specific body mass of the host compiled from standard resources (Dunning 2008);
- host_trait_cat: three major categories of host fitness-related traits (condition, survival, and reproduction);
- host_trait: subcategories of host fitness-related traits within each major category, i.e., condition (body mass, body size, growth, haematology, and physiology), survival (nestling survival and adult survival), and reproduction (reproductive investment and breeding success);
- parasite_type: the type of ectoparasite grouped into eight major categories (ticks, mites, chewing lice, hemipteran bugs, blowfly larvae, dipteran flies, fleas, and mixed);
- study_type: the type of the study classified into four major categories (Abundance - correlational studies of parasite abundance, Presence - correlational studies of parasite presence, Exp_removal - experimental studies based on parasite removal, Exp_infestation - experimental studies based on infestation);
- Zr - effect sizes calculated as Fisher's Z;
- var_Zr - measurement error (variance) of the effect sizes (Fisher's Z);
- year_pub - year of publication;
- ref_ID - reference identity.
References_included spreadsheet contains full references for studies included in the meta-analysis (n = 168).
References_screened spreadsheet contains full references for all studies screened in the meta-analysis (n = 822).
- The file Complex_effects_of_ectoparasites_on_avian_fitness_CODE.txt contains R code used to perform meta-analysis.
- The file phylo_tree_consensus.phy contains consensus phylogenetic tree for species included in the meta-analysis (n = 97).
The consensus tree was summarized from 1000 alternative time-calibrated phylogenies retrieved from the BirdTree webserver (Jetz et al. 2012).