Use of active Monk Parakeet nests by Common Pigeons and response by the host.
Abstract: Common Pigeons (Columba livia) and their feral domestic relatives nest in a variety of sites, but use of nests of other birds has not been reported. I documented 13 nesting attempts by feral Common Pigeons in seven large compound nests of Monk Parakeets (Myiopsitta monachus) in Cordoba, Argentina; at least three attempts produced nestling pigeons. The parakeets did not directly attack the pigeons, but either made an entrance tunnel or completely blocked the chamber entrances with thorny sticks where pigeons nested, eliminating access to chambers and causing the pigeons to abandon their nests.
Article Type: Report
Subject: Social behavior in animals (Research)
Birds (Breeding)
Birds (Research)
Birds (Eggs and nests)
Birds (Observations)
Author: Nores, Manuel
Pub Date: 12/01/2009
Publication: Name: The Wilson Journal of Ornithology Publisher: Wilson Ornithological Society Audience: Academic Format: Magazine/Journal Subject: Biological sciences Copyright: COPYRIGHT 2009 Wilson Ornithological Society ISSN: 1559-4491
Issue: Date: Dec, 2009 Source Volume: 121 Source Issue: 4
Topic: Event Code: 310 Science & research Canadian Subject Form: Animal social behaviour
Geographic: Geographic Scope: Argentina Geographic Code: 3ARGE Argentina
Accession Number: 216267550
Full Text: Feral Common Pigeons (Columba livia) were introduced into Argentina by early colonists and are now residents throughout the country. Breeding colonies occur mostly in cities and towns. Nest sites of Common Pigeons throughout the world include buildings (holes, windows, gutters, roofs, chimneys, air conditioners, water tanks, pots, external ledges, etc.) (Goodwin 1983, Baptista et al. 1997); tree holes (Barclay-Smith 1964, Peterson 1986); caves (Murton and Clarke 1968), and fissures and small cavities in cliffs (Murton and Clarke 1968); and underground sites in abandoned mines (Hendricks 1997). Nesting in nests of other birds has not been documented.

The Monk Parakeet (Myiopsitta monachus) is a neotropical parrot that builds large, conspicuous compound nests, which are usually occupied throughout the year (Forshaw 1978). The nesting structure contains several adjoining nests with separate chambers which are generally oriented down and have an entrance tunnel. A few nests also have lateral chambers without entrance tunnels. Other bird species reported nesting in Monk Parakeet nest chambers include Speckled Teal (Anas flavirostris) (Dabbenne 1918, Port and McKinney 2001); tree ducks (Dendrocygna spp.) (Friedman 1927); Spot-winged Falconet (Spiziapteryx circumcincta) (Martella and Bucher 1984); American Kestrel (Falco sparverius) (De Lucca 1984); and Guira Cuckoo (Guira guira), White Monjita (Xolmis irupero), Screaming Cowbird (Molothrus rufoaxillaris), and Baywing (Agelaioides badius) (Martella et al. 1985).


The study was conducted from 17 October 2007 to 19 August 2008 of a wild population of Monk Parakeets at the Cordoba Zoo in central Argentina where I found feral Common Pigeons using nests of Monk Parakeets. The parrot colony consisted of 12 active nests in a group of Eucalyptus trees, between 15 and 20 m above ground. Eight nests (MP1-MP8) were in two trees. MP1 was the largest nest and had eight chambers. The remaining nests were comparatively small and had only 1-3 chambers. It was not possible to examine the interior of the chambers because of the height of the Monk Parakeet nests. Thus, all observations were made with 10 x 50 binoculars. The nests had a number of lower chambers with entrance tunnels, and an exceptionally high number (11) of lateral chambers without entrance tunnels. I generally visited the colony daily or every other day.


I found 13 feral pigeon nests (FP1-FP13) during 17 October 2007 to 8 August 2008 inside seven different Monk Parakeet nests ~15-20 m above ground grouped in two Eucalyptus trees at the Cordoba Zoo in central Argentina; at least three pigeon nests produced nestlings (Table 1). The pigeon nests, in most cases, were in lateral chambers that had no entrance tunnel. In the only case that pigeons nested in a lower chamber with an entrance tunnel, the tunnel was short and wide. There were several pairs of feral pigeons prospecting the Monk Parakeet nests at all times during the entire study period.


Frequent use of Monk Parakeet nests by feral pigeons at the Cordoba Zoo appears to result from a combination of factors: (1) the lateral chambers of Monk Parakeet nests without entrance tunnels provided pigeons with a suitable breeding place, (2) the parrot nests studied had an exceptional high number of lateral chambers without entrance tunnels, (3) Monk Parakeets and feral pigeons often inhabit parks in cities and towns providing pigeons many opportunities for using Monk Parakeet nest structures, and (4) there were few buildings in the zoo with suitable sites for nesting.

Other birds also use nest chambers of Monk Parakeets for nesting, and responses of Monk Parkeets differ, depending upon the intruder. Martella and Bucher (1984) documented that Monk Parakeets abandoned all nests (15) usurped by Spot-winged Falconets; this behavior is reasonable because this falcon preys on birds. I observed Monk Parakeets to abandon their nests after pigeons became established on only one occasion. Port and McKinney (2001) reported that Monk Parakeets vigorously defended their nests against Speckled Teal and actively chased teal from cavities they occupied. Aggressive behavior of Monk Parakeets was also observed towards Guira Cuckoos, Screaming Cowbirds, and Bay-wings when these birds attempted to usurp parakeet nests (Martella et al. 1985).

I did not observe any attacks of Monk Parakeets on feral pigeons and there appeared to be a harmonious coexistence between parrots and pigeons, which nested simultaneously. Two pairs of pigeons and two pairs of Monk Parakeets nested in MP1, which had eight chambers. Strategies used by Monk Parakeets against feral pigeons were unusual. In one case, parrots completely blocked the entrance of the chamber with thorny sticks where the pigeons had been breeding for 1 month. In three other cases, parrots made an entrance tunnel in the chambers, impeding access for pigeons. In the only case in which pigeons nested in a chamber with an entrance tunnel, parrots made the tunnel longer and narrower. In all cases, pigeons abandoned their nests and parrots established themselves in the chambers. The five cases of obstruction were in small nests with only 1-3 chambers where competition was likely. Parakeets did not obstruct pigeons in MP1, which had eight chambers and five nesting attempts by pigeons.

Generally, there was a period of several days or weeks between pigeon nest establishment and parrot responses. Thus, some pigeon nests may have had nestlings trapped inside. Parrots also made an entrance tunnel after pigeons nested in two of the three chambers where pigeons nested successfully. Only one of the 11 chambers used by pigeons for nesting had an entrance tunnel, which was short and wide. At the end of the study, six of the chambers had an entrance tunnel, and one chamber was blocked with thorny sticks.

The Monk Parakeet behavior observed in this study has not been previously reported (Martella 1985, Port 1988, Martin 1989, Navarro 1989, Aramburu 1991). This behavior has not been observed in other birds that build communal nest structures including Sociable Weaver (Philetairus socius) (Collias and Collias 1977, 1978b), Grey-capped Social Weaver (Pseudonigrita arnaudi) (Payne 1969, Collias and Collias 1980), White-browed Sparrow-Weaver (Plocepasser mahali) (Collias and Collias 1978a), White-billed Buffalo Weaver (Bubalornis albirostris) (Beaver 1993), and Palmchat (Dulus dominicus) (Kirman et al. 1996).


I thank Paul Hendricks, Mark Hauber, David White, Joel Sachs, Thomas Martin, Walt Koenig, Rosendo Fraga, Monica Martella, and Rosana Aramburu for comments. I also appreciate the assistance of Rodrigo Nores, who visited the colony during some periods when I was absent. Joss Heywood and Jorgelina Brasca edited the manuscript.

Received 11 December 2008. Accepted 30 April 2009.


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Manuel Nores (1)

(1) Centro de Zoologia Aplicada/CONICET, C. C. 122, 5000 Cordoba, Argentina; e-mail:
TABLE 1. Nests of Common Pigeons in compound nests of Monk Parakeets
at the Cordoba Zoo, central Argentina.

FP nest   MP nest    Outcome             Response of parakeets

   1         1      Successful               Abandoned nest
   2         2      Abandoned               Blocked entrance
   3         1       Unknown                      None
   4         1      Successful                    None
   5         3      Abandoned    Enlarged and narrowed entrance tunnel
   6         4       Unknown              Added thorny sticks
   7         5      Abandoned          Made two entrance tunnels
   8         7       Unknown                      None
   9         8      Abandoned           Made an entrance tunnel
  10         1      Successful                    None
  11         1      Abandoned                     None
  12         5       Unknown                      None
  13         1      Abandoned                     None

FP nest                    Comments

   1      Only case where parrots abandoned the nest
   8       Storm blew the nest down on 18 March 2008
  11      Storm blew the nest down on 23 August 2008
  13      Storm blew the nest down on 23 August 2008
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