Fear of predators reduces body and physiological condition affecting offspring survival and the ‘quality’ of the survivors
Bibliographic record
Abstract
Abstract Predators affect the survival of developing young by eating them. More recently, the fear of being eaten has been uncovered as a powerful driver of offspring survival reducing recruited offspring numbers by 53%, but the mechanisms driving these effects are not well understood. We exposed song sparrows to predator or non‐predator playbacks throughout three breeding seasons. We followed offspring as eggs through development and into maturity. We quantified the repercussions of being reared in a fearful environment on body (fat, mass, size) and physiological condition using 12 different measures categorized into six systems (oxygen carrying capacity, energy reserves, immune function, antioxidant protection, oxidative stress/damage, glucocorticoids). We further tracked offspring survival in the nest to maturity and determined which measures of condition significantly predicted survival. We report that fear of predators affected offspring condition at all stages of life, with survival consequences. Predator‐playback offspring hatched from heavier eggs (8%) but quickly lost this advantage and never regained it. Nestlings reared by ‘frightened’ parents were as heavy and much leaner than non‐predator playback nestlings. This pattern extended throughout development into maturity where offspring reared by frightened parents were up to 31% leaner and 5% lighter. Predator‐playback nestlings also were evidently in poorer physiological condition, having shorter telomeres, while late dependency stage fledglings carried relatively less uric acid and more haptoglobin perhaps indicative of chronic susceptibility to infection. Only body condition (mass and fat) predicted survival during peak mortality periods (nestling and early fledging), with the leanest lightest offspring from the predator‐playback treatment being least likely to survive. Thereafter, mass predicted survival irrespective of playback treatment. Similarly, at this later stage, offspring with less telomere loss and high uric acid levels survived best regardless of playback group. Our findings reveal that fear of predators is a potent form of early life adversity which persistently alters the condition of offspring affecting early stage survival and the ‘quality’ of the survivors throughout their life. Development is fuelled by food and fear‐induced reductions in parental provisioning at the earliest stages likely instigated these effects, with consequences on the population growth rate. Read the free Plain Language Summary for this article on the Journal blog.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 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) | 0.000 | 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 teacher head, 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".