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. 2024 Dec 23;207(1):15.
doi: 10.1007/s00442-024-05656-2.

Immigration hides the decline caused by an anthropogenic trap and drives the spectacular increase of a mobile predator

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Immigration hides the decline caused by an anthropogenic trap and drives the spectacular increase of a mobile predator

Haruki Natsukawa et al. Oecologia. .

Abstract

Accurate identification of decreasing trends is a prerequisite for successful conservation, but can be challenging when immigration compensates local declines in abundance. Here, we show that a potential declining trend driven by low vital rates was overridden and converted into a spectacular increase by massive immigration into the population of a semi-social raptor, the black kite Milvus migrans, breeding in a highly contaminated area near a major landfill. Immigration was promoted by a growing food-base of live prey, coupled with the attraction exerted by the progressive gathering of a large flock of non-breeders at the area, resulting in an "attraction spiral" that lured large numbers of breeders to settle into a contaminated population incapable of self-sustenance. Immigration was so prevalent that, in little more than a decade, over 95% of the original population was substituted by immigrants, which showed the enormous potential of immigration as a rescue mechanism. At the same time, immigration may hide cryptic threats, as shown here, and expose some species, especially group-living mobile ones, to rapid attraction to anthropogenic subsidies, whose potential role as evolutionary traps is well known. The dynamics exposed here may become increasingly common, affecting many other species in our growingly anthropogenic world. Our results remark the often overlooked importance of immigration in ecology, evolution, and conservation as a key player for population dynamics and their more realistic forecast.

Keywords: Compensatory immigration; Conspecific attraction; Ecological trap; Evolutionary trap; Rescue effect.

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Conflict of interest statement

Declarations. Conflict of interest: There are no conflicts of interest to declare.

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References

    1. Andersen DE (2007) Survey techniques. In: Bird DM, Bildstein KL (eds) Raptor research and management techniques. Hancock House, Washington, pp 89–100
    1. Blanco G (1994) Seasonal abundance of Black Kites associated with the rubbish dump of Madrid, Spain. J Raptor Res 28:242–245
    1. Blanco G (1997) Role of refuse as food for migrant, floater and breeding black kites (Milvus migrans). J Raptor Res 31:71–76
    1. Blanco G, Frías O, Jiménez B, Gómez G (2003) Factors influencing variability and potential uptake routes of heavy metals in black kites exposed to emissions from a solid-waste incinerator. Environ Toxicol Chem 22:2711–2718 - PubMed
    1. Blanco G, Jiménez B, Frías Ó, Millan J, Davila JA (2004) Contamination with nonessential metals from a solid-waste incinerator correlates with nutritional and immunological stress in prefledgling black kites (Milvus migrans). Environ Res 94:94–101 - PubMed

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