Figure 1.
Micro CT coronal sections through bill-tips of five probe-foraging bird species.
A: North Island brown kiwi (Apteryx mantelli), B: bar-tailed godwit (Limosa lapponica), C: Eurasian woodcock (Scolopax rusticola), D: black-winged stilt (Himantopus himantopus), and E: South Island oystercatcher (Haematopus finschi). Consecutive slices are 3 mm apart. Mid-grey areas = keratin and soft tissue, dark-grey to black areas = bone. Scale bar = 2 mm.
Figure 2.
3D reconstructions of the bill-tips of five probe-foraging bird species.
A1-4: the North Island brown kiwi (Apteryx mantelli), B1-4: Eurasian woodcock (Scolopax rusticola), C1-4: bar-tailed godwit (Limosa lapponica), D1-4: South Island oystercatcher (Haematopus finschi), and E1-4: black-winged stilt (Himantopus himantopus). Panel one shows a lateral view, panel two a dorsal view, panel three a ventral view, and panel four a rostral view. The dark grey structure represents the bone and the transparent structure the keratin.
Figure 3.
Histological sections of North Island brown kiwi (Apteryx mantelli) and bar-tailed godwit (Limosa lapponica) bill-tips.
A: Diagram of three coronal sections through a North Island brown kiwi bill, taken at: (1) 9 mm from the tip of the upper bill rhamphotheca (showing upper bill above, lower bill beneath); (2) 6 mm from tip of the upper bill rhamphotheca , sectioned through the sensory pad area forward of the tip of the rhamphotheca of the lower bill); (3) 3 mm from the tip of the upper bill rhamphotheca. Black areas represent the premaxilla and dentary bones. Dark grey shaded areas represent cross sections through the major nerves. Areas of soft tissue are shaded pale grey, the keratin and major blood vessels are left white. Herbst corpuscles (in 3) are white, with a central black line to represent the nerve axon. Bold lines indicate the outer surface of the keratin layer, finer lines indicate the junction between the dermal and keratin layers and the outlines of major blood vessels, nerves, and Herbst corpuscles. In (1), the premaxilla is perforated by the two nasal passages, bordered with bold lines and colored white. B: Sagittal section through a sensory pit in the North Island brown kiwi premaxilla, stained with Masson’s trichrome and C: a sensory pit in the bar-tailed godwit dentary, stained with haematoxylin and eosin. Abbreviations: N: nerves, B: bone. Examples of Herbst corpuscles are highlighted with white arrows. Scale bars = 100 µm.
Figure 4.
Sagittal sections of the brains of six species of birds examined in this study.
Photomicrographs of sagittal sections stained with cresyl violet through the brain of six species of birds examined in this study. The top panel shows the principal sensory trigeminal nucleus (PrV) and the bottom panel the nucleus basorostralis (Bas). The broken black lines indicate the borders of each of the regions present in the sections. Brain sections are shown from North Island brown kiwi (Apteryx mantelli), bar-tailed godwit (Limosa lapponica), Eurasian woodcock (Scolopax rusticola), South Island oystercatcher (Haematopus finschi), black-winged stilt (Himantopus himantopus), and masked lapwing (Vanellus miles). Abbreviations: A: arcopallium, N: nidopallium, H: hyperpallium, E: entopallium, SPC: striatopallidal complex, M: mesopallium, C: caudal, R: rostral, D: dorsal, V: ventral. Scale bars; top panel = 1 mm, bottom panel = 2 mm.
Figure 5.
PrV and Bas volumes relative to the volume of the brain and hindbrain.
Scatterplots of the log-volume of the principal sensory trigeminal nucleus (PrV) and the nucleus basorostralis (Bas, all measurements in mm3). Data from [8] and [37] is included in the analysis. PrV is regressed against A: Brain-PrV volume and B: hindbrain-PrV volume and Bas against C: telencephalon-Bas volume and D: hindbrain volume. E shows Bas regressed against PrV. The solid lines indicate the least-squares linear regression lines and the dotted and broken lines indicate the phylogeny-corrected 90 and 95% confidence interval, respectively. Symbols and colors represent birds and orders as shown in the legend.
Figure 6.
3D reconstructions of brain structures in six species of birds examined in this study.
3D reconstructions of the telencephalon (transparent), nucleus basorostralis (green), striatopallidal complex (blue) and the hyperpallium (red) in six species of birds. Models are shown in a lateral view in the top half of the panel and in a rostral view in the bottom half. Models are shown for North Island brown kiwi (Apteryx mantelli), bar-tailed godwit (Limosa lapponica), Eurasian woodcock (Scolopax rusticola), South Island oystercatcher (Haematopus finschi), black-winged stilt (Himantopus himantopus), and masked lapwing (Vanellus miles).