Exploring the Relationship between Brain Plasticity, Migratory Lifestyle, and Social Structure in Birds

Abstract

Studies in Passerines have found that migrating species recruit more new neurons into brain regions that process spatial information, compared with resident species. This was explained by the greater exposure of migrants to spatial information, indicating that this phenomenon enables enhanced navigational abilities. The aim of the current study was to test this hypothesis in another order—the Columbiformes – using two closely-related dove species—the migrant turtle-dove (Streptopelia turtur) and the resident laughing dove (S. senegalensis), during spring, summer, and autumn. Wild birds were caught, treated with BrdU, and sacrificed 5 weeks later. New neurons were recorded in the hyperpallium apicale, hippocampus and nidopallium caudolaterale regions. We found that in doves, unlike passerines, neuronal recruitment was lower in brains of the migratory species compared with the resident one. This might be due to the high sociality of doves, which forage and migrate in flocks, and therefore can rely on communal spatial knowledge that might enable a reduction in individual navigation efforts. This, in turn, might enable reduced levels of neuronal recruitment. Additionally, we found that unlike in passerines, seasonality does not affect neuronal recruitment in doves. This might be due to their non-territorial and explorative behavior, which exposes them to substantial spatial information all year round. Finally, we discuss the differences in neuronal recruitment between Columbiformes and Passeriformes and their possible evolutionary explanations. Our study emphasizes the need to further investigate this phenomenon in other avian orders and in additional species.

Contrasting migratory journeys and changes in hippocampal astrocyte morphology in shorebirds

“…Because we have no information about the potential influence of sex and age on hippocampal astrocyte morphology in long‐distance migratory birds, and because we did not determine the age of individuals in our sample for technical reasons, it is difficult to discuss these potential influences in detail. However, experience and sex are important variables that have been previously demonstrated to influence hippocampal‐dependent tasks in birds (Astie, Scardamaglia, Muzio, & Reboreda, 2015; Bingman & MacDougall‐Shackleton, 2017; Guigueno, MacDougall‐Shackleton, & Sherry, 2016; Rensel, Ellis, Harvey, & Schlinger, 2015), and migratory behavior is accompanied by changes in hippocampal volume and neurogenesis (Barkan, Roll, Yom‐Tov, Wassenaar, & Barnea, 2016; Barkan, Yom‐Tov, & Barnea, 2017; de Morais Magalhaes et al., 2017). Thus, these variables should be considered in future studies of hippocampal astrocyte morphologies in long‐distance migratory birds.…”

Hippocampal Astrocytes in Migrating and Wintering Semipalmated Sandpiper Calidris pusilla

“…Because we have no information in the literature about potential influence of sex and age on hippocampal astrocytes morphology in long-distance migratory birds, and we did not measure the age of individuals in our sample due to technical limitations, it is difficult to discuss these potential influences in detail. However, experience and sex are important variables that have been previously demonstrated to influence hippocampal-dependent tasks in birds ( Astié et al, 2015 ; Rensel et al, 2015 ; Guigueno et al, 2016 ; Bingman and MacDougall-Shackleton, 2017 ), and migratory behavior is accompanied by hippocampal morphological changes including volume and neurogenesis ( Barkan et al, 2016 , 2017 ; de Morais Magalhães et al, 2017 ). Thus, these variables should be considered in future studies of hippocampal astrocytes morphologies in long-distance migratory birds.…”

Shorebirds’ Longer Migratory Distances Are Associated With Larger ADCYAP1 Microsatellites and Greater Morphological Complexity of Hippocampal Astrocytes

“…Because there is no information in the literature about potential influence of sex and age on hippocampal astrocyte morphology in long-distance migratory birds, and we did not measure the age of individuals in our sample due to technical limitations, it is difficult to discuss these potential influences in detail. However, experience and sex are important variables that have been previously demonstrated to influence hippocampaldependent tasks in birds (Astié et al, 2015;Rensel et al, 2015;Guigueno et al, 2016;Bingman and MacDougall-Shackleton, 2017), and migratory behavior is accompanied by hippocampal morphological changes including volume, and neurogenesis (Barkan et al, 2016(Barkan et al, , 2017de Morais Magalhaes et al, 2017) which should be considered in future studies of hippocampal astrocyte morphologies in long-distance migratory birds.…”