|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
STATUS OF THE ROSY-FACED LOVEBIRD IN PHOENIX, ARIZONA |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Kurt A. Radamaker, 8741 E. San Pedro Drive, Scottsdale, AZ 85258 The Rosy-faced Lovebird (Agapornis roseicollis) is a small, colorful parrot which is a popular cage bird in the U.S. and elsewhere. Since at least the mid-1980s, feral flocks of this species have been reported breeding in residential neighborhoods of the greater Phoenix area. Most exotic species that escape do not survive long in the wild and fewer still establish breeding populations in non-native habitats. However during the past 25 years, populations of these lovebirds have increased and expanded and they have become regular city park and backyard visitors to many greater Phoenix neighborhoods.
Formerly known as Peach-faced, this lovebird is native to dry wooded country in southwestern Africa, up to an elevation of 1500 m (Collar 1997). Its natural range is poorly known, but the species is generally found in Angola, southward along the coast through Namibia to Northern Cape Province, South Africa (Juniper and Parr 1998). It is fond of arid regions but depends on areas near water, and exhibits nomadic tendencies where water is scarce or unavailable. In Africa this lovebird is found in scrubby hillsides and tree-lined watercourses including river canyons and in rocky terrain where area rainfall exceeds 100 mm (Collar 1997). It is a colonial breeder with natural breeding sites in inaccessible and often vertical cracks in sandstone koppies— small usually rocky hills rising up from the African grasslands—or steep rock faces on exfoliating granite (Simmons 1997). However, it is highly adaptable and also nests and roosts in Sociable Weaver (Philetairus socius) nests, as well as in artificial structures and junction boxes on power poles, and in other unnatural habitats (Simmons 1997). The wild population status of the Rosy-faced Lovebird is not exactly known. However, Simmons (1997) indicated that it is unlikely that any range contraction has occurred during the 20th century, and that it is more likely that populations have increased with the provision of water points in previously dry areas, and of artificial structures in which it can nest. Simmons believes that the species is widespread and abundant in the wild. Captive birds have escaped in urban areas of South Africa but have not become established (Collar 1997).
The Rosy-faced Lovebird was first reported as breeding in the greater Phoenix area in a residential neighborhood in the East Valley near the Apache Junction and Mesa city border in 1987 (Michael A. Moore pers. comm.). Moore also noted successful nesting in 1988 and he observed flocks continuously in this area until he moved from the neighborhood in 1995. From their first detection of nesting in 1987, the population had greatly expanded by the end of the Arizona Breeding Bird Atlas project (1993-2000). In the mid-1990s colonies and flocks were noted in several eastern greater Phoenix area neighborhoods and by 2000 lovebirds had been detected on ten residential atlas blocks encompassing approximately 100 square miles from northwest Phoenix and north Scottsdale south to Tempe and Guadalupe and then west to Apache Junction (Corman 2005). This evidence strongly suggests the continued presence and breeding of lovebirds in the greater Phoenix area for 20+ years. Further documentation of nesting of Rosy-faced Lovebirds was published in the Arizona Breeding Bird Atlas (Corman 2005). According to atlasers, nesting activity is generally initiated in April or May and eggs are likely laid from April-June, but nesting may occur irregularly throughout the year, a seasonal pattern similar to that observed in the species’ native African habitat (Forshaw 1977). In Arizona adults have been observed carrying nesting material (strips of vegetation tucked among tail feathers) as early as late February. The most commonly reported nesting (and roosting) sites for lovebirds in the greater Phoenix metro area are under the dead fronds of untrimmed palm trees, especially Canary Island date palm (Phoenix canariensis), and shallow cavities in saguaros (Carnegiea gigantea), with fewer reports among house roof tiles (Corman 2005).
METHODS The area censused (Figure 1) extended from
west Phoenix, north to Scottsdale and Hwy. RESULTS The results of this half-day census were enlightening. A total of 948 Rosy-faced Lovebirds detected. This number far exceeded our predictions. Nearly half of the birds were detected within Phoenix city limits, with a combined total >300 also counted in Mesa and Scottsdale. Parts of the lovebird’s known range (e.g., NE. Apache Junction, Cave Creek, E. Gilbert, and NW Phoenix) were not surveyed and we estimate that less than 50 percent of suitable habitat in the greater Phoenix area was surveyed. Furthermore, lovebirds can be difficult to detect, for example when perched quietly in vegetation. Approximately a third of the census teams detected no lovebirds, even though some were surveying areas where these birds were detected within a few days to a week prior (Table 1). Based on these factors, we estimate the population of Rosy-faced Lovebirds in the greater Phoenix area to consist of at least 2500 individuals.
DISCUSSION It is clear the Rosy-faced Lovebird population is growing, but it is difficult to know how fast it is
increasing or expanding because little has been
previously documented about population size or
distribution in the greater Phoenix area. However, it is important to note that little evidence suggests
that Rosy-faced Lovebirds have established any
populations in surrounding natural desert or riparian
habitats away from human developments. This may
have to do with limited availability to water,
appropriate food sources, and/or nest cavities
Most of the range of the Rosy-faced Lovebird in the greater Phoenix area is outside boundaries of Christmas Bird Counts (CBCs) and little information is, therefore, available on the species’ population growth and distribution. Furthermore, the lovebirds have been largely ignored on CBCs where they do occur. Few birders or ornithologists have interest in conducting studies of exotic birds in urban or suburban areas (Pranty and Garrett 2003). Among biologists and birders is a propensity to ignore exotic birds. Almost no one wants to gather data regarding them; indeed, one sometimes hears cries, often delusional, to eradicate many exotics (Smith and Smith 1993). These unfounded and irrational cries of eradication still echo today regarding the lovebirds. In fact, a few census participants were reluctant to take part at first, and some lovebird enthusiasts refused to participate out of concern that the census data would be used to initiate an eradication effort. Rosy-faced Lovebird locality and population information has been compiled and mapped since 1999 by Greg Clark (http://mirror-pole.com/collpage/pf_loveb/pfl_1.htm). This web site uses Google maps technology, where observers map site location and include the date, numbers present, and other notes such as roost sites and nesting activity. The web site shows that populations have expanded during the past decade in all directions from original population centers (Figures 2 and 3), but it is difficult to determine the actual rate of growth and expansion entered on this website since 1999, as some of the increase in detections likely results from additional lovebird enthusiasts learning about the website and submitting information.
During the late 1980s, Moore regularly observed 6-9 lovebirds near the Apache Junction and Mesa city border (pers. comm.). In two separate years these birds were accompanied by young that had recently fledged from cavities in tall saguaros. Moore also noted that the time of fledging coincided with the fruiting of the saguaros and he observed adults feeding on saguaro fruit. Rosy-faced Lovebirds are probably opportunistic breeders like Budgerigars (Melopsittacus undulatus), starting a breeding cycle when conditions are optimal (R. Jonker pers. comm.). The current lovebird population is apparently self-sustaining and not entirely dependent on humans for food and shelter. Furthermore, Rosy-faced Lovebirds in the Phoenix area are sufficiently numerous and widespread that any control or eradication program would presumably be unsuccessful, and surely misguided. Indeed, to our knowledge lovebirds have shown little to no negative impact on native bird populations or habitats. Their colonial nesting habits and propensity to nest in palms in urban areas reduce any widespread competition for nest sites. Even widespread trimming of palms has had no appreciable effect on numbers, as birds readily move to adjacent areas to roost following local trimming, only to return to these same palms several months later. Lovebirds have also shown resilience to environmental conditions: Phoenix area lovebirds have survived temperatures ranging from -4˚C (January 2007) to 50˚C (June 1990). Given the relatively mild climate in the greater Phoenix area, sufficient food and water sources throughout the year, and the fact that birds may produce two or three broods per year, the number of offspring produced is sufficient to maintain and likely increase the
population. The typical lifespan in captivity of Rosy-faced Lovebird is 15 to 25 years. The typical lifespan in the wild is unknown but expected to be shorter than in captivity (De Grahl 1984), still giving each pair ample opportunity to replenish and expand populations. Furthermore, adult lovebirds appear to be fairly wary and swift on the wing, with few reports of their being caught by likely urban predators such as raptors or outdoor cats.
Environmental conditions appear to favor a sustainable lovebird population, but psittacine beak and feather disease is always a looming threat. This viral disease affects all Psittacinae parrots and has the potential to become a major threat to all species of wild parrots and to modern aviculture, due to the increasing international legal and illegal bird trade (Wikipedia 2011). In view of the above and of the history of some exotic bird populations in the U.S. (e.g., Pranty 2001) the long-term status of the Rosy-faced Lovebird in Arizona is not predictable. However in the greater Phoenix area, they are widespread, their population is growing, and there is little doubt that this charismatic little psittacid will continue to be part of Arizona’s avifauna for the foreseeable future. ACKNOWLEDGEMENTS We thank Greg Clark for access to his mirror-pole site and use of his data and maps, to Michael C. Moore for his initial lovebird
observations, and to Pierre Deviche and Brendon Grice for use of their lovebird photos. We also want to thank Bill Pranty and
Roelant Jonker for their helpful comments and review, and to each of the Lovebird Census participants: Herb Andrews, Joe
Beals, Ken Bielek, Linda Bielek, Karena Black, Mary Lou Blackert, Phyllis Bofferding, Michelle Browning, Jean Bylbie, Michael
Casner, Matt Chew, Troy Corman, Dom D’Agosto, Cindy Deatsman, Joy Dingley, Adam Fiandaca, Herb Fibel, Mike Foley, Joyce
Francis, Cathie Galloway, Thomas Gaskill, Kathleen Halligan, Trish Henry, Diana Herron, Shero Holland, Frank Insana, Brian Ison,
Bud Johnson, Crissy Jones, Cristina Jones, Tom Jones, Paul Kinslow, Jim Kopitzke, Paul LaFontaine, Larry Langstaff, Susan Ledlow,
Tom Lewis, Vivian MacKinnon, Randall Mains, Leslie Marcus, Ettienne Martin, Phyllis Martin, Sue McCall, James McKay, Garrett
McKnight, Barry McNeill, Connie McNeill, Jeanette Nickels, Carlos Oldham, Joanne Pennington, Jan Perry, Ann Peterson, Anne LITERATURE CITED CITES (2004) Deletion of Agapornis roseicollis from Appendix II. Thirteenth meeting of the Conference of the Parties Bangkok
(Thailand), 2-14 October 2004. CITES-Listed Species on the World Wide Web: Collar, N.J. 1997. Rosy-faced Lovebird. P. 410 in J. Del Hoyo, A. Elliott, and J. Sargatal, eds. Handbook of the Birds of the World, Vol. 4, Sandgrouse to Cuckoos, Lynx Edicions, Barcelona.
Accepted 11 July 2011 Revised 15, September 2011
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|