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An illustration of the temperate scarlet tanager (Piranga olivacea) and tropical crimson‐backed tanager (Ramphocelus dimidiatus) by Tara Rodden Robinson
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Parental care in birds varies among species and geographic regions. Incubation behavior influences embryonic development rate and varies substantially among species.
We studied attendance at the nest by videoing nests or collecting data from the literature for 112 species in north temperate and lowland tropical sites, then associated patterns of in...
Citations
... Consequently, parents at higher latitudes need to return to the nest more frequently to maintain optimal egg temperature, resulting in a shorter off-bout duration (Austin et al., 2019;White & Kinney, 1974). ...
Uniparental incubating birds must resolve the trade‐off between self‐maintenance and incubation. This balance manifests through diverse incubation behaviours that vary significantly among species and geographic regions. However, limited research has examined the variability of incubation behaviours across species and regions.
Using Bayesian phylogenetic mixed models, we investigated how three incubation behaviours (off‐bout frequency, off‐bout duration and incubation constancy) vary with latitude across 201 uniparental incubating bird species.
Our findings reveal distinct incubation strategies adopted by uniparental birds across latitudes. Species at lower latitudes exhibit fewer off‐bouts and, meanwhile, have longer off‐bout durations. Conversely, those at higher latitudes exhibit more frequent but shorter off‐bouts. Notably, a clear latitude‐dependent pattern emerges in incubation constancy, with higher latitudes showing greater incubation constancy. Additionally, smaller‐bodied birds tend to take more frequent off‐bouts. Significant variations in off‐bout frequency were observed across different habitats. Herbivorous species, in particular, show higher incubation constancy compared to omnivorous and carnivorous birds.
These findings offer valuable insights into the association of latitudinal variation with the evolutionary dynamics of life histories in uniparental incubating birds.
... While we were unable to collect sufficient data on nest attendance for Tree Swallows, Eastern Bluebirds had lower nest attendance and lower mean nest temperatures than the open-cup species we investigated.The reason for this lower attendance and nest temperature remains unclear, but the safer nest conditions may allow for greater selfmaintenance by the incubating female and a corresponding slower embryonic development, or the conditions with cavities may better buffer against extreme temperature fluctuations. Additionally, this may be due to differences in incubation patterns (i.e., partial incubation) and how time in the nest is distributed (e.g., seeAustin et al., 2019;Wang & Beissinger, 2011), but more research is needed to examine incubation duration in the context of predation risk and the development of high-quality young. ...
Avian eggs develop outside of the female body, and therefore embryonic development is subject to multiple internal (physiological) and external (ecological) factors. Embryonic developmental rate has important consequences for survival. Within species, embryos that develop too quickly often experience deformities, disorders, or mortality, while embryos that develop slowly risk inviability and increase the time they are exposed to various sources of mortality in the nest. These contrasting forces may lead to interspecific variation in developmental rates. We investigated potential factors affecting embryonic heart rate (EHR), a proxy of development, across 14 passerine species in the field. More specifically, we investigated if nest predation risk, clutch size, seasonality, and egg volume influenced EHR. From previous research, we expected, and found, that EHR was positively associated with embryonic age and egg temperature. Species with greater nest predation risk had higher EHR, shorter incubation periods, and lower nest temperature variance. EHR increased as the season progressed and with egg volume, while EHR declined with clutch size. Bird species exhibit varying strategies to increase nestling and fledgling survival in response to predation risk, and these results suggest that variation in embryonic development may be related to species‐specific differences in nest predation risk.
... Die Vogelarten der Welt unterscheiden sich in ihrer Brutbiologie beträchtlich, so zum Beispiel in der Brutphänologie (Capilla-Lasheras et al. 2022), der Gelegegrösse (z.B. Boyer et al. 2010, Martin et al. 2000, der Bebrütungs-und Nestlingsdauer (Martin et al. 2000, Roff et al. 2005, im Nestlingswachstum (Remes und Martin 2002), im Bruterfolg (Martin 1995, Brawn et al. 2011) und in der elterlichen Betreuung der Jungvögel (Reynolds und Székely 1997, Austin et al. 2019. Vergleichende Studien von brutbiologischen Daten verschiedener Vogelarten, -familien und ökologischer Gruppen ermöglichen die Untersuchung der Evolution von Lebensgeschichten (Life-history evolution; Badyaev und Ghalambor 2001, Martin 2004, Wiersma et al. 2007, Naef-Daenzer und Grüebler 2016. ...
... Incubation is a fundamental component of avian reproduction, and species differ widely in their incubation rhythm and nest attentiveness (percentage of daytime that eggs are incubated) (Conway & Martin 2000a,b;Matysioková & Remeš 2014, 2018Austin et al. 2019). Honeyeaters constitute the largest family of passerines in Australia, yet incubation periods are unknown for 23 (33%) of the 70 species, excluding chats, and the role of the male and female in incubation is unknown in 30 species (43%) (data from Higgins et al. 2001). ...
... In temperate south-eastern New South Wales, a female White-naped Honeyeater incubated for 77% of the time (n = 4 h at one nest), with incubation and off-bouts averaging 6.0 and 3.8 minutes (n = 10 in each case), respectively (Marchant 1986). The much higher nest attentiveness and shorter duration of incubation and offbouts of the White-naped Honeyeater, compared with the morphologically very similar White-throated Honeyeater, are most likely related to climatic differences between the temperate and subtropical study areas, respectively, as passerines breeding in higher ambient temperatures tend to have longer incubation and off-bouts than those in colder environments (Conway & Martin 2000a;Matysioková & Remeš 2018;Austin et al. 2019). ...
The role of the male and female in the incubation of eggs is unknown in 30 of the 70 species of Australian honeyeaters, but in most of the remainder, only the female is thought to incubate. Nevertheless, incubation by both male and female is known to occur in six species, including the Brown-headed Honeyeater Melithreptus brevirostris. I observed and video-recorded activities at two nests of one group of four Black-chinned Honeyeaters M. gularis gularis in south-eastern Queensland. Nest attentiveness (incubation constancy) averaged 88% over three sample days. At least two birds participated in incubation, as evidenced by numerous change-overs, strongly suggesting that both male and female were involved. Incubation bouts averaged 7.2 minutes, but varied significantly over the 3 days, and off-bouts averaged 1.3 minutes but did not vary significantly. Nestling provisioning rates varied from 7.5 to 14.4 feeds h-1 on the fourth and thirteenth days after the estimated hatching day. Although cooperative breeding could not be confirmed, up to three birds were seen at this nest during the nestling stage, and up to three at the second nest before incubation began. Breeding records indicate that in southeastern Queensland laying peaks in winter, beginning in late autumn, 2 months earlier than records suggest in New South Wales.
... Parental care has evolved multiple times and a wide diversity of parental care strategies exist across phylogenetic lineages (Royle et al., 2012), such as egg attendance (e.g., in birds; Austin et al., 2019), offspring transportation (e.g., in arachnids; Shaffer & Formanowicz, 1996) and food provisioning (e.g., in mammals; Gloneková et al., 2020). Different taxa have evolved different investment strategies, including female-only care (e.g., most mammals; Gubernick & Klopfer, 1981), male-only care (e.g., most fishes; Goldberg et al., 2020) and biparental care (e.g., most birds; Cockburn, 2006). ...
Dendrobatid poison frogs are known for their diverse parental care behaviours, including terrestrial egg attendance. While usually this behaviour is conducted by males, this study compared the pre-hatching investment of males and females in Ranitomeya imitator , a species with biparental care. Although males tended to spend more time with their eggs overall, there was no difference between sexes when comparing different types of care behaviour. Furthermore, both sexes increased general care behaviour when caring for more than one clutch. The finding that the sexes are relatively equal in their contribution to basic parental care forms provides a basis to understand why biparental care is stable in this species.
... These consequences are also investigated in the avian literature during incubation when ectothermic eggs are developing (Ar & Sidis 2002, DuRant et al. 2013, Berntsen & Bech 2016, Griffith et al. 2016). On the one hand, ambient temperature can directly influence embryonic temperature during parental off-bouts that can last for multiple hours, as is common in tropical species , Austin et al. 2019). Yet, the effects of variation in ambient temperature on egg temperature have been traditionally considered to be limited in species with high natural attentiveness (Drent 1972, 1975, Silver 1983, DuRant et al. 2013. ...
... Indeed, in the field, additional uncontrolled factors exist that change on a fine scale, such as food availability (Chalfun & Martin, 2007), nest predation rate (LaManna & Martin 2016) and body condition of the adults (Gorman & Nager, 2004). Additionally, nest insulation properties and clutch size (Austin et al. 2019) also need to be taken into consideration because they can have repercussions on the thermal conditions experienced by eggs and on parental behaviour. All of the above ecological aspects may influence incubation effort and thus potentially mask the effects of ambient temperature. ...
... Ambient temperature can have strong influences on clutch temperature when considering tropical species with long off-bouts that leave their nests unattended for up to 6 h a day , Austin et al. 2019. Here, we found that clutches at 30°C were not warmer than those at 18°C in Zebra Finches, a species with extremely high overall attentiveness. ...
In birds ambient temperature can influence adult incubation behaviour, energy budget, egg temperature, and embryonic development with downstream effects on offspring survival. Surprisingly, experimental manipulations of the whole nesting environment to test causes and consequences of variation in incubation pattern, energy balance, egg temperature, and the duration of development are lacking to date. Here, we bred pairs of Zebra Finches Taeniopygia guttata under controlled conditions at 18° and 30°C and measured clutch size, temperature, hatching success, parental attentiveness and the length of the embryonic period. We found that when breeding at the higher temperature, males, but not females, increased the number of incubation bouts on the nest. Instead, females, but not males, reduced their attentiveness towards the clutch overall. Eggs showed no temperature differences between the two treatments and bigger clutches experienced lower temperatures. This suggests that parental behaviour may buffer the effect of ambient conditions on the thermal profile of eggs, including species with high rates of parental attentiveness. Warmer conditions yielded higher hatching rates but did not cause measurable differences in the length of embryonic development. Still, smaller clutches hatched earlier in accordance with the higher temperature experienced. Additionally, we used data from the literature to calculate parental energy expenditure and demonstrate that this was substantially different across the two treatments, although predicted energy savings from reduced attentiveness at 30°C appeared negligible. These results suggest that when food is available, ambient temperature and not energy trade‐offs may explain variation in incubation behaviour.
... Nest predation rate is, on average, higher in the tropics, but its distribution shows extensive overlap comparing tropical and temperate regions [10,[24][25][26]. Predation might influence parental nest attendance and feeding behavior, as parents seek to reduce perceived predation risk to themselves and to their offspring by limiting their activity around the nest site [20,[27][28][29][30]. Lower parental attendance could influence development rates by reducing incubation temperatures and, later, the rate of food provisioning to the nestlings, thereby prolonging development time. ...
... Parental attendance (uni-vs. bi-parental care) also could influence the amount of care provided to eggs and nestlings, which, in turn, could influence embryonic and post-embryonic development [30]. Thus, lower attendance, often associated with femaleonly incubation and parental care, might limit growth by limiting temperature, or food resources, for optimal development [20,30]. ...
... bi-parental care) also could influence the amount of care provided to eggs and nestlings, which, in turn, could influence embryonic and post-embryonic development [30]. Thus, lower attendance, often associated with femaleonly incubation and parental care, might limit growth by limiting temperature, or food resources, for optimal development [20,30]. ...
We studied avian development in 49 to 153 species of temperate and tropical New World passerine birds to determine how growth rates, and incubation and nestling periods, varied in relation to other life-history traits. We collected growth data and generated unbiased mass and tarsus growth rate estimates (mass n = 92 species, tarsus n = 49 species), and measured incubation period (n = 151) and nestling period (n = 153), which we analyzed with respect to region, egg mass, adult mass, clutch size, parental care type, nest type, daily nest predation rate (DMR), and nest height. We investigated covariation of life-history and natural-history attributes with the four development traits after controlling for phylogeny. Species in our lowland tropical sample grew 20% (incubation period), 25% (mass growth rate), and 26% (tarsus growth rate) more slowly than in our temperate sample. Nestling period did not vary with respect to latitude, which suggests that tropical songbirds fledge in a less well-developed state than temperate species. Suboscine species typically exhibited slower embryonic and post-embryonic growth than oscine passerines regardless of their breeding region. This pattern of slow development in tropical species could reflect phylogenetic effects based on unknown physiological attributes. Time-dependent nest mortality was unrelated to nestling mass growth rate, tarsus growth rate, and incubation period, but was significantly associated with nestling period. This suggests that nest predation, the predominant cause of nest loss in songbirds, does not exert strong selection on physiologically constrained traits, such as embryonic and post-embryonic growth, among our samples of temperate and lowland tropical songbird species. Nestling period, which is evolutionarily more labile than growth rate, was significantly shorter in birds exposed to higher rates of nest loss and nesting at lower heights, among other traits. Differences in life-history variation across latitudes provide insight into how unique ecological characteristics of each region influence physiological processes of passerines, and thus, how they can shape the evolution of life histories. While development traits clearly vary with respect to latitude, trait distributions overlap broadly. Life-history and natural history associations differ for each development trait, which suggests that unique selective pressures or constraints influence the evolution of each trait.
... Ambient temperature is an important contributor to avian incubation behavior, which in turn influences growth and development (Ardia et al. 2009, Martin et al. 2015. We did not measure egg temperature, and additional work is needed to understand the physiological consequences of lower egg temperatures and slower growth rates, particularly those for offspring quality (Ricklefs et al. 2017, Martin et al. 2018, Austin et al. 2019. Evolution can favor slow growth as a mechanism to increase offspring quality (Arendt 1997, Ricklefs et al. 2018, whereas slow growth arising from extrinsic factors such as low temperature is expected to yield lower, rather than higher, quality individuals (Martin et al. 2013(Martin et al. , 2018. ...
Avian incubation provides an opportunity to test how parental behavior and ecological conditions interact to shape variation in offspring traits along geographic gradients. In particular, the duration of the incubation period is shorter at higher latitudes, but the degree to which this pattern arises from genetic divergence in rates of growth and development versus from parentally‐mediated variation in egg temperatures is controversial. At higher latitudes parents have higher daytime incubation attentiveness, i.e. they spend a greater proportion of the day on the nest. However, interpreting latitudinal variation in behavior is complicated by latitudinal patterns in ambient temperature and day length. Here, we use 24‐h video recordings to compare the incubation behavior of orange‐crowned warblers Leiothlypis celata in California and Alaska and test how attentiveness varies between populations and as a function of temperature. Birds in Alaska had higher nest attentiveness during the day, despite experiencing similar ambient temperatures. However, when analyzed over 24‐h, the longer nighttime period in California almost entirely canceled out daytime attentiveness differences between populations, and differences in 24‐h attentiveness were small. Our work highlights how incorporating nighttime incubation behavior qualitatively alters latitudinal patterns of attentiveness, and how lower ambient temperatures cannot account for the higher attentiveness in a high latitude population. These populations differ in their incubation period lengths, and differentiating between evolved versus environmentally‐induced variation in offspring growth and development will help understand the fitness consequences of variation in developmental periods. This article is protected by copyright. All rights reserved.
Tree cavities play a vital ecological role in urban areas by providing essential habitats and resources for a variety of animal taxa, including cavity-nesting birds, mammals, and insects, thereby contributing to urban biodiversity and ecosystem functioning. While most studies on cavity availability focus on forest habitats, little is known about their presence in urban environments. In cities, reduced tree densities, the management of tree branches for public safety, and the limited presence of tree-excavating species may all affect the availability of tree cavities. In this study, we asked four key questions: (1) What is the frequency of tree cavities across different habitats in Udaipur city, Rajasthan, India? (2) How are cavities distributed on trees species? (3) How do the characteristics of natural and excavated cavities differ across habitats? (4) What factors influence cavity availability? We surveyed 487 individual trees representing 69 species across five urban habitats, with the majority being native (62.31%). A total of 474 cavities were recorded in 260 tree individuals, predominantly in temple areas (60.34%) and residential colonies (22.78%). Natural cavities (67.67%) were more common than excavated cavities (32.33%), with natural cavities mainly found on the main trunk, while excavated cavities were more frequently located on primary and secondary branches. The characteristics of cavity-bearing trees did not significantly differ (P > 0.05) from control trees, nor did they vary significantly across habitats. While cavity heights varied slightly across habitats, this was not statistically significant (P > 0.05), and cavity height increased with tree size. Habitat was identified as a primary significant (P < 0.05) variable influenced cavity availability per site. Our research showed the potential of present trees in Indian small growing city particularly in temple areas and residential colonies, to enhance urban habitats and to promote the conservation of biodiversity including cavity nesters and excavators.
Movement patterns and habitat selection of animals have important implications for ecology and evolution. Darwin's finches are a classic model system for ecological and evolutionary studies, yet their spatial ecology remains poorly studied. We tagged and radio-tracked five (three females, two males) medium ground finches (Geospiza fortis) to examine the feasibility of telemetry for understanding their movement and habitat use. Based on 143 locations collected during a 3-week period, we analyzed for the first time home-range size and habitat selection patterns of finches at El Garrapatero, an arid coastal ecosystem on Santa Cruz Island (Galápagos). The average 95% home range and 50% core area for G. fortis in the breeding season was 20.54 ha ± 4.04 ha SE and 4.03 ha ± 1.11 ha SE, respectively. For most of the finches, their home range covered a diverse set of habitats. Three finches positively selected the dry-forest habitat, while the other habitats seemed to be either negatively selected or simply neglected by the finches. In addition, we noted a communal roosting behavior in an area close to the ocean, where the vegetation is greener and denser than the more inland dry-forest vegetation. We show that telemetry on Darwin's finches provides valuable data to understand the movement ecology of the species. Based on our results, we propose a series of questions about the ecology and evolution of Darwin's finches that can be addressed using telemetry.
