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Incubation is a crucial part of the avian life cycle; eggs must be kept warm enough for embryos to develop. As egg temperatures drop rapidly when not being actively incubated, birds must balance the thermal requirements of their developing offspring with their own energy requirements when deciding to make a feeding trip. Incubation behavior can vary with ambient temperature, and across the breeding cycle. Here, we examine the incubation behavior of black-capped (Poecile atricapillus) and mountain (P. gambeli) chickadees where they live together in the Front Range of the Colorado Rocky Mountains. We deployed iButton temperature monitors in and around chickadee nests to record nest and ambient temperatures during the incubation period. For each deployment, we visually inspected temperature data to determine whether incubation was detected. For each deployment in which incubation was detected we quantified incubation behavior using the incR R package. Across the four nests for which incubation was detected, females (the incubating sex) spent about 85% of the day incubating, and left the nest about 32 times per day for an average of 6.7 minutes. On average, nest temperatures were maintained around 35˚C.
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This content will become publicly available on February 27, 2026
Respiratory challenges and oedema development in zebra finch embryos under reduced pore area
Global warming is one of the primary drivers of habitat loss and population decline in numerous species, including birds, amphibians and marine life. Avian embryos exhibit ectothermic phenotypes during most of their incubation period and are also vulnerable to rising temperatures when parents cannot cool the nests. This vulnerability stems from their unique respiratory mechanisms, which utilize eggshell pores to exchange respiratory gases. The number of pores is fixed at oviposition, and embryos may experience hypoxia during later developmental stages, especially when exposed to elevated ambient/incubation temperatures. Our preliminary study on zebra finch (Taeniopygia guttata castanotis) embryos, where we covered 30% of the shell surface with beeswax and incubated at high (38.9°C) temperature, revealed that half of the individuals that failed to hatch had developed oedema in the hind neck region. This study shows that such physical anomalies occur during incubation prior to death. We found that embryos with oedema had a higher head-to-body ratio, independent of their relative brain mass. Furthermore, oedema formation was correlated with darker-coloured hearts, suggesting reduced blood oxygenation in these embryos. These results highlight the physiological challenges embryos face under suboptimal incubation conditions. This article is part of the theme issue ‘The biology of the avian respiratory system’.
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- PAR ID:
- 10592192
- Publisher / Repository:
- The Royal Society Publishing
- Date Published:
- Journal Name:
- Philosophical Transactions of the Royal Society B: Biological Sciences
- Volume:
- 380
- Issue:
- 1920
- ISSN:
- 0962-8436
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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