Short Note

Ground cavity nest temperatures and their relevance to Blue Swallow Hirundo atrocaerulea conservation

  • James Wakelin
  • Amy-Leigh Wilson
  • Colleen T Downs

Abstract

Blue Swallows Hirundo atrocaerulea are Critically Endangered within South Africa. They nest in natural underground holes in mist-belt grasslands. Temperature dataloggers were used to record ground cavity nest (Tn) and ambient temperature (Ta) for one artificial and 11 natural Blue Swallow nests. Mean ground cavity Tn was significantly different to mean Ta. Tn ranged from 17.0 ± 0.1 ºC to 28.5 ± 0.3 ºC and varied less than Ta (14.0 ± 0.2 to 47.7 ± 0.4 ºC). Mean ground cavity Tn averaged 3.3 ± 0.9 ºC warmer than mean Ta for 58% of nests, and mean Ta averaged 2.6 ± 0.5 ºC warmer than mean ground cavity Tn for 42% of nests. There was no significant difference in mean ground cavity Tn for the aardvark-excavated holes (22.7 ± 1.6 ºC) and sinkholes (21.5 ± 1.2 ºC). Blue Swallows also nest in man-made holes, potentially a way to increase nesting sites. Mean aardvark-excavated Tn (19.2 ± 0.1 ºC) was significantly warmer than mean artificial cavity Tn (18.5 ± 0.2 ºC). Further investigation of breeding success of Blue Swallows in relation to Tn, incubation strategies and predation risk needs to be addressed in future studies for a better understanding of their reproductive ecology.

Keywords: artificial nest, Blue Swallows, critically endangered, microclimate, natural nest

OSTRICH 2013, 84(3): 221–226

Author Biographies

James Wakelin
Scientific Services, Ezemvelo KZN Wildlife, PO Box 13053, Cascades 3202, South Africa; School of Life Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville 3209, South Africa
Amy-Leigh Wilson
School of Life Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville 3209, South Africa
Colleen T Downs
School of Life Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville 3209, South Africa
Published
2013-12-10
Section
Articles

Journal Identifiers


eISSN: 1727-947X
print ISSN: 0030-6525