Soil penetrability as a key factor affecting the nesting of burrowing birds

Abstract

Soil penetrability resistance was found to be crucial for nest site selection of all three Central European burrowing bird species-Sand Martins (Riparia riparia), European Bee-eaters (Merops apiaster), and Eurasian Kingfishers (Alcedo atthis). Soil penetrability resistance measurements were used to find out whether increased hardness of unexcavated banks is the key factor affecting the presence of burrowing birds. All three species avoided banks composed of too compact or too loose soils. Birds discriminated not only between high-and low-quality breeding banks, but also between different soil strata within banks. In banks with generally low penetrability resistance, Sand Martins preferred soil strata with the highest available penetrability resistance and compactness to avoid hole collapses. There was a preference for hard soil below holes to serve as a resistant platform when birds begin to dig their holes. In Sand Martins, the penetrability resistance level affected physical characteristics of holes such as tunnel length and dimensions of the orifices. Excessive compactness-and probably not high talus presence-was a major cause of abandonment of Sand Martin localities. A high penetrability resistance is the crucial factor for site selection in Sand Martins.

The impact of soil texture on the selection of nesting sites by the Malachite Kingfisher (Alcedinidae: Alcedo cristata Pallas 1764)

“…The results of the present study further suggest that, as has been documented in other burrowing bird species (Heneberg 2009), soil texture determines the selection of nesting sites in the Malachite Kingfisher. Our results indicate that even a slight difference in the proportion of clay can substantially affect the suitability of banks for the establishment of nests.…”

“…Different nesting bird species in sympatry thus partition the environment along pedological gradients. For instance, Bee-eaters and Sand Martins establish their nests in banks with contrasting soil texture to avoid competition (Heneberg 2009 …”

“…For instance, the soil of the banks used by Bee-eaters Merops apiaster contains a load of sand particles between 28.0 and 9.2 μm that is 20 times higher than that of the banks used by Sand Martins Riparia riparia (Henerberg 2004, Yuan et al 2006. In particular, soil grain size determines the depth of the tunnels, which in turn correlates with the reproductive success (Heneberg 2009). In Sand Martins and the European Kingfisher Alcedo atthis, Heneberg (2001Heneberg ( , 2004 demonstrated that the highest rates of reproductive success are achieved in areas with a soil texture of <900 μm and 40 000 μm, respectively.…”

Loess and bee-eaters I: Ground properties affecting the nesting of European bee-eaters (Merops apiaster L.1758) in loess deposits

“…The sand martin is perhaps the best known of the loess-living birds (and has been studied at length by, in particular, Heneberg 2003Heneberg , 2009). This paper is about the ground rather than the birds, and the birds might be seen as experimental operators who manipulate the ground thus enabling its properties to be assessed.…”

Loess and Bee-eaters IV: Distribution of the rainbowbird (Merops ornatus Latham 1801) in Australia

“…This is a study of ground and its suitability for bee-eater nesting. The idea that the nature and properties of the ground are a major control of nesting is largely down to Heneberg (2009, 2013, Heneberg & Simecek 2004 and it was he who pointed out the interaction of the two key properties of ground strength and excavateability. The ground must be strong enough to support the tunnel but it must have properties that allow the birds to build a nesting tunnel.…”