Haemosporidian parasites of Canada Warblers ( Cardellina canadensis ) and Black-throated Blue Warblers ( Setophaga caerulescens ): prevalence, diversity, and associations with physiological condition during migration
Bibliographic record
Abstract
Avian malaria (Plasmodium spp.) and related haemosporidian parasites (Leucocytozoon spp. and Haemoproteus spp.) are widespread in birds, yet studies investigating prevalence and diversity of haemosporidians are lacking for many Nearctic-Neotropical migrants. Furthermore, the impact that infections may have on the condition or behavior of birds during migration is still poorly understood. Here, we used nested PCR and DNA sequencing to determine parasite prevalence and identify genetic lineages of haemosporidians in Canada Warblers (Cardellina canadensis) and Black-throated Blue Warblers (Setophaga caerulescens) during their migration stopover on the south shore of Lake Ontario. We further evaluated if haemosporidian infections were related to immune condition, as assessed via total white blood cell (WBC) counts and heterophil/lymphocyte (H/L) ratios, or refueling patterns and/or migration timing. We found a haemosporidian prevalence of 51.5% in 66 birds; however, there was a greater haemosporidian prevalence in Black-throated Blue Warblers relative to Canada Warblers. We detected 15 cytochrome b lineages of parasites, including 4 novel lineages. In Black-throated Blue Warblers, infected birds had significantly higher total WBC counts compared to uninfected birds. Across species, females had lower H/L ratios when infected, whereas the opposite trend was observed in males. Plasma metabolites (triglyceride, β-hydroxybutyrate, uric acid) were not associated with infection status, and infection was not related to arrival date at the spring stopover site. Results provide insight into the diversity of haemosporidians that infect two species of migratory warblers and illustrate that blood parasite infections are a routine challenge that these birds face during migration. Although haemosporidian infections may be associated with a heightened immune response in some scenarios, the findings of this correlative study provide no evidence that Canada Warblers and Black-throated Blue Warblers experience physiological or behavioral trade-offs as a result of infections.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".