Do migrant and resident species differ in the timing of increases in reproductive and thyroid hormone secretion and body mass? A case study in the comparison of pre-breeding physiological rhythms in the Eurasian Skylark and Asian Short-toed Lark

Abstract

Background: Physiological preparation for reproduction in small passerines involves the increased secretion of reproductive hormones, elevation of the metabolic rate and energy storage, all of which are essential for reproduction. However, it is unclear whether the timing of the physiological processes involved is the same in resident and migrant species that breed in the same area. To answer this question, we compared temporal variation in the plasma concentration of luteinizing hormone (LH), testosterone (T), estradiol (E 2 ), triiothyronine (T 3 ) and body mass, between a migrant species, the Eurasian Skylark (Alauda arvensis) and a resident species, the Asian Short-toed Lark (Calandrella cheleensis), both of which breed in northeastern Inner Mongolia, China, during the 2014 and 2015 breeding seasons.Methods: Twenty adult Eurasian Skylarks and twenty Asian Short-toed Larks were captured on March 15, 2014 and 2015 and housed in out-door aviaries. Plasma LH, T (males), E 2 (females), T 3 and the body mass of each bird were measured every six days from March 25 to May 6. Results:With the exception of T, which peaked earlier in the Asian Short-toed Lark in 2014, plasma concentrations of LH, T, E 2 andT 3 of both species peaked at almost the same time. However, Asian Short-toed Larks attained peak body mass earlier than Eurasian Skylarks. Plasma T 3 concentrations peaked 12 days earlier than plasma LH in both species. Generally, plasma LH, T, E 2 , T 3 and body mass, peaked earlier in both species in 2014 than 2015. Conclusions:The timing of pre-reproductive changes in the endocrine system and energy metabolism can be the same in migrant and resident species; however, residents may accumulate energy reserves faster than migrants. Although migration does not affect the timing of pre-breeding reproductive and metabolic changes, migrant species may need more time to increase their body mass. T levels in resident species may be accelerated by higher spring temperatures that may also advance the pre-breeding preparation of both migrants and residents.

Maternally transferred thyroid hormones and life‐history variation in birds

“…Higher yolk THs might mirror elevated circulating THs in migratory species, which might be directly or indirectly linked to their higher BMRs (Jetz et al, 2008). In line with this explanation, in two closely related skylark species, the migratory Eurasian skylarks Alauda arvensis had higher pre‐breeding blood T3 levels than the resident Asian short‐toed larks Calandrella cheleensis (Zhao et al, 2017). In fish, a marine migratory ecotype of the stickleback Gasterosteus aculeatus also had higher plasma T4 than a stream resident ecotype (Kitano et al, 2010).…”

The effects of migration on the immunity of Black-Headed Gulls (<i>Chroicocephalus ridibundus</i>: Laridae)

“…Male gulls arrive earlier than females at breeding sites [ 19 ]. Male American redstarts ( Setophaga ruticilla ), Eurasian skylarks ( Alauda arvensis ), and Asian short-toed larks ( Calandrella cheleensis ) also migrate earlier than females and have been shown to already produce some reproductive-related hormones at Spring migration, influencing their body mass and immune function [ 41 , 47 ]. In this study, some tested parameters were significantly different between the Spring migration period and other periods; therefore, it is necessary to evaluate sex-related differences with a sufficient sample size.…”

Differential cell stress responses to food availability by the nestlings of Asian Short-toed Lark (Calandrella cheleensis)

“…Because there is only one significant nymph abundance peak once a year in the study area (Chen and Gong 2005;Guo et al 2009), and the hatching time of nestlings has to be synchronized with the time of nymph abundance peak. According to our previous study, the species displays significantly within year individual variation in the timing of breeding behavior (Zhang et al 2017;Zhao et al 2017). Although there was an obvious hatching peak in one breeding season, there were some nestlings hatched outside this peak (Zhang et al 2017).…”