Composition or encounter? Decomposing the altitude and night-time damage premiums in United States wildlife strikes, 1990 to 2026

Denys Kolomiiets 

Damaging wildlife strikes in the United States are known to be commoner higher above the ground and, for some taxa, after dark. Both patterns are usually read as composition: altitude and darkness change which animals an aircraft can meet, and large animals damage aircraft. That reading has not been tested, because the published height and light-condition tables are marginal — they pool every taxon. Using the full FAA National Wildlife Strike Database (354,564 reports, 22,210 damaging), this paper decomposes both premiums within animal family and within species. The night premium is partly composition: in general aviation the crude odds ratio of 1.41 falls to 1.20 once strata are taxon-matched, and white-tailed deer account for most of the difference. It does not vanish — a residual of about 1.2 persists in general aviation and is unchanged by adjustment in the commercial segment (1.17 crude, 1.22 adjusted). The altitude premium is not composition at all. Taxon-matching raises the odds ratio in both segments (general aviation 2.92 to 3.20; commercial 2.12 to 2.39), so the assemblage struck at altitude masks rather than creates the effect, and the association holds inside 22 of 23 individually identified species with adequate sample (median odds ratio 3.60). Within a species, a strike above 500 ft is several times likelier to damage the aircraft than a strike at or below it. Whether the residual reflects encounter energy or a reporting asymmetry cannot be settled from a voluntary-reporting record, and both readings are stated.