Seasonal Variation in Forebrain Region Sizes in Male Ruffed Grouse <b><i>(Bonasa umbellus)</i></b>

Abstract

The song system of songbirds has provided significant insight into the underlying mechanisms and behavioural consequences of seasonal neuroplasticity. The extent to which seasonal changes in brain region volumes occur in non-songbird species has, however, remained largely untested. Here, we tested whether brain region volumes varied with season in the ruffed grouse (Bonasa umbellus), a gallinaceous bird that produces a unique wing-beating display known as ‘drumming' as its primary form of courtship behaviour. Using unbiased stereology, we measured the sizes of the cerebellum, nucleus rotundus, telencephalon, mesopallium, hippocampal formation, striatopallidal complex and arcopallium across spring males, fall males and fall females. The majority of these brain regions did not vary significantly across these three groups. The two exceptions were the striatopallidal complex and arcopallium, both of which were significantly larger in spring males that are actively drumming. These seasonal changes in volume strongly implicate the striatopallidal complex and arcopallium as key structures in the production and/or modulation of the ruffed grouse drumming display and represent the first evidence of seasonal plasticity in the telencephalon underlying a non-vocal courtship behaviour. Our findings also suggest that seasonal plasticity in the striatopallidal complex and arcopallium might be a trait that is shared across many bird species and that both structures are related to the production of multiple forms of courtship and not just learned song.

Landscape effects on the contemporary genetic structure of Ruffed Grouse (Bonasa umbellus) populations

“…An additional 49 samples were taken from birds collected at the same two sites between 2010 and 2015 for unrelated anatomical studies (Corfield, Harada, & Iwaniuk, 2013;Corfield, Krilow, Vande Ligt, & Iwaniuk, 2013;Krilow & Iwaniuk, 2015). All procedures adhered to the Canada Council for Animal Care regulations were approved by the University of Lethbridge Animal Welfare Committee and collected under research permits issued by Alberta Environment and Parks.…”

A Comparison of Telencephalon Composition among Chickens, Junglefowl, and Wild Galliforms

“…Specifically, the STGR were collected in the fall from hunters, whereas the other grouse were all collected in the spring breeding season. Seasonal effects on telencephalon region sizes do occur in RUGR [31], and it is therefore possible that the STGR differ from other grouse in our multivariate analyses due to seasonal effects. That said, it is clear that RUGR and prairie chickens differ significantly in telencephalon composition from chickens and junglefowl and all of those individuals were males in breeding condition, thus limiting any seasonal effects from those comparisons.…”

Behavioural responses of male ruffed grouse (Bonasa umbellus, L.) to playbacks of drumming displays

“…However, social interactions in ruffed grouse are extremely rare and have primarily been inferred from removing males from drumming logs and those logs being occupied by other males within a breeding season (Boag, ; Gullion, ). In cases where we have removed grouse for anatomical studies (Corfield, Harada, et al., 2013; Corfield, Krilow, et al., 2013; Corfield et al., ; Krilow & Iwaniuk, ), the drumming log has remained unoccupied for the rest of the breeding season and Berkeley () found no log turnover across several breeding seasons in the same study area as Gullion (). Given this variation in whether males can displace or replace one another at a drumming log and the general lack of any observable social interactions, if social dominance is responsible for the differential response, it is unclear how dominance status could be assessed in ruffed grouse.…”

“…A total of 64 males were provided 109 playbacks from 2012 to 2015. All of the recordings used were from males that were removed from the population for parallel anatomical studies (Corfield, Harada, & Iwaniuk, 2013; Corfield, Krilow, Ligt, & Iwaniuk, 2013; Corfield, Long, Krilow, Wylie, & Iwaniuk, ; Krilow & Iwaniuk, ), so none of these males were exposed to playbacks from themselves. From these, 32 males received a single stimulus playback (pulse rate = 4.981 Hz) and 32 males were provided two playback sessions with two different stimuli: one with a fast drumming rate and another one with a slow rate.…”