Cliff Swallow (Hirundo pyrrhonota) Anna Kornoelje
Iosco Co., MI © Robert Epstein
(Click to view a comparison of Atlas I to II) The colorful Cliff Swallow can be “bricks” that comprise their nests (Samuel 1971, Eaton 1988). The Cliff Swallow is widely distinguished by its habit of nesting in large distributed throughout Michigan with the colonies of up to several thousand gourd shaped greatest concentrations occurring in the mud nests at a single breeding site (Brown and southeastern LP and decreasing numbers Brown 1995). The Cliff Swallow is distributed moving northwards to the northern LP and UP. throughout the United States, Canada and This contrasts with data from MBBA I which Mexico during the breeding season, and shows the opposite trend of Cliff Swallows although it is absent from the southeastern being most numerous in the UP and decreasing states, numbers of Cliff Swallows in this region southwards. A comparison of townships in have been increasing (Wolinski 1988). The Cliff which Cliff Swallows were documented shows Swallow breeds throughout Michigan and is an interesting reversal of trends. The data from usually associated with human constructions MBBA I show that in the UP, NLP and SLP such as bridges, barns, dams and lighthouses percentage of townships with possible, probable (Wolinski 1988). and confirmed Cliff Swallow documentation are
47.5%, 38.6% and 24.1% respectively. The data Distribution for the same category from the MBBA II shows The Cliff Swallow’s breeding range has that the UP, NLP and SLP documented Cliff expanded considerably in the southeastern Swallows in 16.9%, 32.8% and 36.7% of United States in conjunction with the townships respectively. It is unclear why this construction of bridges, buildings, and culverts shift in population distribution has occurred, in the past 100–150 years. In Michigan, the Cliff however House Sparrows are one of the most Swallow was probably limited by nesting sites significant threats to Cliff Swallow nesting before European settlement (Wolinski 1988). attempts (Wolinski 1988). Sparrows destroy However, the widespread construction of eggs in order to usurp nests and a single House buildings and bridges has provided opportunity Sparrow may clean out 12–15 nests before for these swallows to expand their breeding selecting one for its own (Brown and Brown range in Michigan. Also, while Cliff Swallows 1995). An increase in House Sparrows in the UP are found commonly in association with human or a decrease in LP House Sparrows may be the development, they also require a nearby source cause of this range shift, however further study of clay or clayey mud with which they make the
© 2011 Kalamazoo Nature Center Cliff Swallow (Hirundo pyrrhonota) Anna Kornoelje should be undertaken to confirm the reasons for decreasing trend in Ontario has also been the shift. observed. North of the road system in northern Ontario, there was no apparent decline of Breeding Biology swallows; however, in road accessible areas, a The Cliff Swallow begins egg laying in marked decline was observed (Cadman et al. Michigan as early as May and peak laying time 2007). The authors posit that as open fields are continues through June (Brown and Brown abandoned and returned to scrub land and forest, 1995). Three to five eggs comprise a typical the habitat becomes less suitable for Cliff clutch (Myres 1957). Nestlings are reported to Swallows (Cadman et al. 2007). A similar shift fledge between 20 and 26 days after hatching in habitat types may be occurring in Michigan, (Brown and Brown 1995). The Cliff Swallow corresponding with the southward shift of Cliff has been documented in Michigan occupying Swallows. breeding sites in groups that generally number around five pairs, although colonies as large as Conservation Needs 3,500 pairs have been documented in the United The Cliff Swallow is not listed on any States (Wolinski 1988, Brown and Brown threatened or endangered species lists. House 1995). The Cliff Swallow uses complex Sparrows are a significant threat to nest success, vocalizations to identify its offspring within the and removal of sparrows can result in an crowded colony and is also quite noisy when increase of Cliff Swallows in suitable habitats alarmed (Brown and Brown 1995, Cadman et al. (Wolinski 1988). Ectoparasites such as the 2007). hematophagous, or blood sucking, swallow bug can also be a threat to nest success. Swallow Abundance and Population Trends bugs increase with colony size and nest density (Click to view trends from the BBS) (Brown and Brown 1995). The swallow’s habit In the Midwest it appears that Cliff Swallow of nesting under bridges can result in collisions populations are increasing. The BBS trends with cars. A recent study showed that Cliff show that in FWS Region 3 between 1983 and swallow nesting on bridges can be reduced by 2008, average swallows observed per route the use of alarm and distress calls and surface increased from approximately eight birds to modification with plastic sheeting (Conklin et approximately 15 birds. In Michigan average al. 2009). swallows observed per route increased from approximately three birds to approximately five birds. This general increase is especially interesting when compared with the southward shift in distribution. Block Summaries from MBBA I show confirmed presence of Cliff Swallows in 206 blocks in the UP, 162 blocks in the NLP and 92 blocks in the SLP. This may be contrasted with Block Summaries from MBBA II in which confirmed presence of Cliff Swallows occurred in 51 blocks in the UP, 74 blocks in the NLP and 152 blocks in the SLP. However, BBS trends indicate a slight decline in Cliff Swallow numbers between 2001 and 2007, although this trend was not statistically significant (Sauer et al. 2008). Further, a
© 2011 Kalamazoo Nature Center Cliff Swallow (Hirundo pyrrhonota) Anna Kornoelje
Literature Cited Suggested Citation
Brown, C., and M. Brown. 1986. Ectoparasitism Kornoelje, A.R. 2011. Cliff Swallow (Hirundo as a Cost of Coloniality in Cliff Swallows pyrrhonota). In Chartier, A.T., J.J. Baldy, (Hirundo pyrrhonota). Ecology 67: 1206- and J.M. Brenneman (eds.). 2010-2011. The 1218. Second Michigan Breeding Bird Atlas. Brown C.R. and M.B. Brown. 1995. Cliff Kalamazoo Nature Center. Kalamazoo, MI. Swallow (Hirundo pyrrhonota). In The Accessed online at:
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