Urban parakeets in Northern Illinois: A 40-year perspective

Monk parakeets (Myiopsitta monachus) are the most abundant and widely distributed of the naturalized parrots in the United States. We summarize monk parakeet population data from 1970 to 2010 for northern Illinois, one of the best-known populations. Throughout the 1970s, parakeets were seen in small numbers at scattered locations, but none of the nesting sites persisted and the birds either died or moved elsewhere. The species became established in the Hyde Park neighborhood of Chicago in 1979 and this population grew exponentially and expanded over the next 25?years, doubling in size every 2 to 3?years. In the mid to late 1990s parakeets became established in many other localities in the Chicago region. The population in Hyde Park began to rapidly decline in 2005, a trend also exhibited in national counts. The reasons for this decline are unknown but we suggest that the decline is more apparent than real and that the decline in Hyde Park is the result of shifts in population structure from a few dense aggregations to progressively more spatially separated smaller groups. As evidence for this, the population of parakeets in the greater Chicago region does not appear to have declined but is still growing in size and distribution. Monk parakeets are a novel addition to many urban ecosystems, with a neutral impact to most other bird species but an increasingly complex interaction with human residents in urban areas.