The desert exploiter: An overabundant crow species exhibits a neighborhood diffusion pattern into the southern region of Israel

Amit Salomon, Giorgi Kozhoridze, Eyal Shochat, Ofer Ovadia

Research output: Contribution to journalArticlepeer-review

Abstract

Understanding the causes of spread of overabundant species plays a key role in deciphering their invasion mechanisms, while providing managers with targeted management actions to control their spread. The objective of this research was to quantify the spread of Hooded Crow (Corvus cornix) in Israel and to elucidate the causes of its spread. Long-term occurrence data of Hooded Crow sightings were used to analyze the species range expansion rate. This dataset was analyzed with a range of climatic, normalized difference vegetation index (NDVI), and land-use variables. Analysis of opportunistic presence-only data, corrected for possible sampling biases, illustrated traveling waves of eastward expansion, from the Mediterranean coast into Israel's central mountain range, and a star-like pattern of spread southward into the northwestern Negev desert. A diffusion equation model revealed an expansion rate of 1.60 km year-1. Land-use analysis revealed an affinity of sighted individuals toward urban and low vegetation land types. Hooded Crow sightings were positively correlated with annual precipitation, with the remaining variation being negatively correlated with precipitation during the wettest quarter. Species distribution modeling suggested that the species has established new populations and is currently expanding its range. The slow rate of dispersal is consistent with a neighborhood diffusion pattern, corresponding to the species life-history traits. Human-managed environments, including low-cover agricultural fields, provide constant available food and nesting trees, allowing the Hooded Crow to thrive all year-round. Precipitation may aid in enhancing Hooded Crow tolerance toward other unfavorable physical conditions. In light of these new findings, management plans ought to recognize centers of Hooded Crow activity as indicators of highly disturbed native wildlife communities. Also, our findings emphasize the need to establish agri-environmental schemes (AES) in such areas, which would raise community resistance to overabundant species. As AES are currently not in place on a national scale, and since their creation has the power to improve landscape connectivity of native species, this last component is especially necessary. LAY SUMMARY: For the past several decades, the Hooded Crow (Corvus cornix) has been spreading throughout Israel, particularly into the Negev desert. This highly adaptable overabundant generalist species has been suspected of depredating native fauna, including IUCN red-listed species. The present study is the first to quantify the spread of this overabundant species in its southern geographical range and to reveal its driving forces. Our analysis illustrated traveling waves of range expansion of Hooded Crows into agricultural-dominated lands in the northwestern Negev of Israel. The rate of this spread within the last two decades was relatively slow, corresponding to a neighborhood diffusion pattern. Hooded Crow individuals were predominantly sighted in low vegetation cover and urban land-use types. Management of Hooded Crows at the expanding range edges located within agricultural and human-altered lands should emphasize agri-environmental schemes, elevating the resistance of the local community to overabundant agricultural and urban species.

Original languageEnglish
JournalCondor
Volume123
Issue number3
DOIs
StatePublished - 1 Aug 2021

Keywords

  • Corvus cornix
  • count data
  • desert
  • diffusion
  • invasive species
  • land-use
  • spatial distribution
  • spread

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