Can Ingestion of Lead Shot and Poisons Change Population Trends of Three European Birds: Grey Partridge, Common Buzzard, and Red Kite?

Abstract

Little is known about the magnitude of the effects of lead shot ingestion alone or combined with poisons (e.g., in bait or seeds/granules containing pesticides) on population size, growth, and extinction of non-waterbird avian species that ingest these substances. We used population models to create example scenarios demonstrating how changes in these parameters might affect three susceptible species: grey partridge (Perdix perdix), common buzzard (Buteo buteo), and red kite (Milvus milvus). We added or subtracted estimates of mortality due to lead shot ingestion (4–16% of mortality, depending on species) and poisons (4–46% of mortality) reported in the UK or France to observed mortality of studied populations after models were calibrated to observed population trends. Observed trends were decreasing for partridge (in continental Europe), stable for buzzard (in Germany), and increasing for red kite (in Wales). Although lead shot ingestion and poison at modeled levels did not change the trend direction for the three species, they reduced population size and slowed population growth. Lead shot ingestion at modeled rates reduced population size of partridges by 10%, and when combined with bait and pesticide poisons, by 18%. For buzzards, decrease in mean population size by lead shot and poisons combined was much smaller (≤ 1%). The red kite population has been recovering; however, modeled lead shot ingestion reduced its annual growth rate from 6.5% to 4%, slowing recovery. If mortality from poisoned baits could be removed, the kite population could potentially increase at a rapid annual rate of 12%. The effects are somewhat higher if ingestion of these substances additionally causes sublethal reproductive impairment. These results have uncertainty but suggest that declining or recovering populations are most sensitive to lead shot or poison ingestion, and removal of poisoned baits can have a positive impact on recovering raptor populations that frequently feed on carrion.

Relative contributions of fixed and dynamic heterogeneity to variation in lifetime reproductive success in kestrels (Falco tinnunculus)

“…The Gini indices (0.84 for females, 0.87 for males) and the probability to produce zero LRS (0.73 for females, 0.80 for males) in our population were even higher than most of the populations studied by Tuljapurkar et al (2020). In addition, these metrics of our population were higher than the ones calculated for, for example, Black‐legged kittiwakes ( Rissa tridactyla , Gini‐index = 0.62, probability LRS = 0:0.33, data from Steiner & Tuljapurkar, 2012), a German population of Common buzzards ( Buteo buteo , Gini‐index = 0.73, probability LRS = 0:0.58, data from Meyer, Meyer, Francisco, Holder, & Verdonck, 2016), a population of Red kites from Wales ( Milvus milvus , Gini‐index = 0.69, probability LRS = 0:0.50, data from Meyer et al, 2016), and comparable to for example, an American population of Peregrine falcons ( Falco peregrinus , Gini‐index = 0.83, probability LRS = 0:0.70, data from Deines et al, 2007) and a Spanish population of the related Lesser Kestrel ( Falco naumanni , Gini‐index = 0.82, probability LRS = 0:0.68, data from Hiraldo, Negro, Donazar, & Gaona, 1996).…”

Demographic modeling to fine‐tune conservation targets: importance of pre‐adults for the decline of an endangered raptor

“…Here we update the earlier demographic model with age‐dependent estimates from local individual‐based data. Overall, the abovementioned widespread declines suffered by Red Kites throughout Europe are likely promoted by the sensitivity of this species to several anthropogenic risks, such as secondary poisoning, rodenticide applications, electrocution, shooting, collisions with wind turbines, and contamination (e.g., Villafuerte et al 1998, Gómara et al 2008, Aebischer 2009, Knott et al 2009, Schaub 2012, Tavecchia et al 2012, Tenan et al 2012, Meyer et al 2016, Blanco et al 2017). Although these risks might be less important than in the past in some regions (Martinez‐Abraín et al 2009), the facultative scavenging habits of the Red Kite and its hunting mode of meticulously quartering the ground make this species particularly susceptible to mortality by illegal poisoned baits (Márquez et al 2012, Tavecchia et al 2012, Mateo‐Tomás et al 2020).…”

Effects of lead from ammunition on birds and other wildlife: A review and update

“…Meyer et al (2016) used population models to create example scenarios demonstrating how mortality from lead poisoning and other poisons might affect the populations of three susceptible species: grey partridge ( Perdix perdix ) in continental Europe, common buzzard in Germany and red kite in Wales. Lead gunshot ingestion and poisoning at modelled levels (4–16% for lead poisoning depending on species) affected populations by reducing population size and slowing population growth.…”