Comparison of breeding strategies of two sympatric thrush species in an alpine environment

Abstract

Closely related birds that occur sympatrically will inevitably differ in the acquisition of food resources, nest site selection, and breeding times. The successful coexistence of birds that breed in the same area can be determined by investigating how they divide limited resources and reduce interspecific competition. Our study area is located at the eastern foot of the Qinghai-Tibet Plateau, with a high altitude and low annual average temperature. In this study, the life history characteristics and reproductive ecological parameters of two closely related species, the Chestnut Thrush (Turdus rubrocanus) and the Kessler’s Thrush (Turdus kessleri), were compared in detail in April–July of 2020, 2021, and 2022 in the scrub along the Liqiu River in Xinduqiao Town, Tibetan Autonomous Prefecture of Garzê, Sichuan. The results showed no differences in nesting material, nest cup size, clutch size, feeding strategy of nestlings, brood food type, and reproductive effectiveness between the Chestnut Thrush and the Kessler’s Thrush. However, the Kessler’s Thrush had a higher nesting height, thicker nest wall, earlier breeding time, smaller eggs, fewer brooding frequent and a longer brooding time compared to the Chestnut Thrush. In addition, they invested more time in parental care, resulting in a faster growth and development rate. The results indicate that birds with different ranges and breeding in the same range show convergent and divergent life history characteristics in terms of reproductive biology. Chestnut Thrush with low reproductive altitude shows the characteristics of low-altitude bird reproduction in part of reproductive biology, while Kessler’s Thrush with high reproductive altitude shows the characteristics of high-altitude bird reproduction in part of reproductive biology.

Comparison of Reproductive Strategies between Two Sympatric Copsychus Passerines

“…Under limited spatial and food resources for breeding, avian species are compelled to engage in competitive interactions as survival strategies [20,21]. Therefore, bird species coexisting in ecological niches and experiencing resource competition in the same habitat have evolved distinct reproductive strategies, including differentiation of nestsite preferences [22][23][24], breeding timing, and nest material utilization [25][26][27][28] to enhance their respective fitness and facilitate coexistence within the same habitat [19]. Among the forms of competition above, competition for nest sites could be particularly intense among secondary cavity-nesting birds, as the availability of suitable secondary nest sites in the same area is limited [29].…”

Variations in the Reproductive Strategies of Different Charadrius alexandrinus Populations in Xinjiang, China

“…A large number of studies have described the diversity of reproductive life history strategies among birds due to variations in environmental conditions and individual morphology [16][17][18][19][20][21][22][23][24][25][26][27][28]. Additionally, the body size and the reproductive characteristics in populations of the same species are also influenced by environmental and phylogenetic factors [19,22,29]. The reproductive life history characteristics of birds, such as egg-laying time, egg size, clutch size, and clutch volume, are usually considered to be the main indicators to measure reproductive output [10,17,19,22,[27][28][29][30].…”

“…Additionally, the body size and the reproductive characteristics in populations of the same species are also influenced by environmental and phylogenetic factors [19,22,29]. The reproductive life history characteristics of birds, such as egg-laying time, egg size, clutch size, and clutch volume, are usually considered to be the main indicators to measure reproductive output [10,17,19,22,[27][28][29][30]. These indicators can effectively reveal the different reproductive traits of birds in different environments due to adaptive trade-offs and constraint of physiological mechanisms, which can be interpreted as different reproductive life history strategies [17,19,22,[27][28][29][30][31].…”

“…The reproductive life history characteristics of birds, such as egg-laying time, egg size, clutch size, and clutch volume, are usually considered to be the main indicators to measure reproductive output [10,17,19,22,[27][28][29][30]. These indicators can effectively reveal the different reproductive traits of birds in different environments due to adaptive trade-offs and constraint of physiological mechanisms, which can be interpreted as different reproductive life history strategies [17,19,22,[27][28][29][30][31]. For example, the egg size and clutch size of birds can be adjusted according to changes in the egg-laying date, ambient temperature, food resources, and female physical condition [4,17,32,33].…”

Variations in the Reproductive Strategies of Different Charadrius alexandrinus Populations in Xinjiang, China

“…Large numbers of studies have described the diversity of reproductive life history strategies of birds due to variation of environmental conditions and individual morphology [16][17][18][19][20][21][22][23][24][25][26][27][28][29]. Additionally, the body size and reproductive characteristics in populations of the same species is also influenced by environmental and phylogenetic factors [30][31][32]. Reproductive life history characteristics of birds, such as egg-laying time, egg size, clutch size and clutch volume, are usually considered to be the main indicators to measure reproductive output [10,[27][28][29][30][31][32][33].…”