Temperature modulates photoperiodic seasonal responses in the subtropical tree sparrow, Passer montanus

Abstract

We studied the effects of temperature on the photoperiodic regulation of seasonal reproduction and related events in the subtropical tree sparrow at Shillong, India. In the first experiment, one group of birds was maintained in an outdoor open aviary receiving natural photoperiod and temperature conditions, while the other group was exposed to natural photoperiod and constant temperature of 17 ± 2 °C in an outdoor closed aviary for 12 months. Although both sexes achieved peak gonadal growth at the same time (May) under the two conditions, gonadal regression and feathers molt were delayed under the temperature controlled condition. In the second experiment, the groups of birds were exposed to three different temperatures (17, 25 and 30 °C) under both long (LD-14L:10D) and short (SD-9L:15D) day lengths for 7 months. Birds showed relatively small but significant gonadal growth, darkening of bill color and feathers molt only at 30 °C under SD. However, they behaved as though they were under natural conditions and exhibited the above responses significantly at all temperatures under LD. There was delayed gonadal regression at the lower temperature (17 °C), while feathers molt delayed with increasing temperature (25, 30 °C) under LD. These results clearly indicate that temperature modulates photoperiodic seasonal responses in the tree sparrow.

Seasonality in tropical birds

“…The synergistic role of supplementary environmental cues (other than photic cues) has been studied in many tropical birds. The temperature being a variable factor, could potentially serve as an additional cue to fine‐tune the timing of reproduction (Dixit et al, 2018; Wingfield, 1980). However, the response to temperature appears to be species‐specific.…”

Seasonal differences in hypothalamic thyroid‐stimulating hormone β, gonadotropin‐releasing hormone‐I and deiodinase expression between migrant and resident subspecies of white‐crowned sparrow (Zonotrichia leucophrys)

“…61 Similarly, there are several laboratory studies using songbirds, including the related Mountain White-crowned sparrow (Z. l. oriantha) that have demonstrated acceleration of shifts in MBH gene expression and gonadal growth in response to changes in temperature. 25,29,62,63 However, temperature was investigated as a supplementary cue in all of these studies, enhancing or reducing the effects of photoperiod cues; thus, caution in direct application must be taken. The alternative model proposed above for residents represents an inversion of the classic seasonal breeding model with non-photoperiodic environmental cues serving as the primary stimulus and photoperiod serving as a supplementary cue to enhance HPG axis activation as the birds approach breeding.…”

Utilization of biomolecules as fuel energy and their physiological mechanism during migration in birds- A review

“…On the other hand, body fattening is generally lacking or to a limited extent, even if it occurs, in non-migratory birds. Since the body fat serves as stored food and fuel during migratory flights in birds, its deposition in non-migratory resident birds, that have an easy access to food in their surroundings throughout, would hamper their flight activities (Dixit and Singh, 2011;2012Dixit et al, 2018). These body stores comprise mainly lipids and proteins (Lindstorm and Piersma, 1993;Piersma et al, 1999).…”