Chick Age Research Articles

Disturbance‐dependent Yellow‐legged Gull (Larus michahellis) predation on Larid chicks decreases with chick age

Predation is one of the key factors shaping the dynamics of animal populations. In birds, nest loss due to predation can be a significant cause of low reproductive success. Ground‐nesting birds are among the bird groups most susceptible to predation, mainly because their nests are easily accessible to a broad suite of potential predators. For these birds, anthropogenic disturbances can generate changes in nest predation risk by altering their antipredator behaviour and also by altering the behaviour of the predator species, i.e. the predator becoming much more aware of predation opportunities due to frequent disturbances and/or motivated to repeat predation attempts when some are successful. To date, most previous studies investigating this have focused on a single effect, either predation or disturbance, on chick survival. It remains unknown how the risk of predation with and without disturbance varies with chick age. In this study, we used behavioural observations to assess how the interaction between predators and disturbance affects predation risk in chicks and how this interacts with chick age. Specifically, we investigated the effect of disturbance caused by humans and stray dogs on the predation of Slender‐billed Gull Chroicocephalus genei chicks by Yellow‐legged Gulls Larus michahellis, and whether this depended on the age of the chicks. Our results revealed that disturbance had a significant positive effect on predation measures of Slender‐billed Gull chicks by Yellow‐legged Gulls, but that this effect was mediated both by disturbance type and the age of chicks. Stray dogs entering the colony had a stronger disturbance effect on chicks than passing humans, increasing predation risk by Yellow‐legged Gulls. Our results also showed that chick age interacts with disturbance type to determine the predation risk. This is probably mediated by chicks' capacity to escape predation by gathering in a single large crèche that runs into the water when disturbed. To preserve Slender‐billed Gull colonies in one of its few remaining breeding sites in Tunisia, and as gulls tend to react even when the disturbance occurs relatively far from the colonies, it is crucial to (1) restrict human access to dikes and islets where large colonies breed and (2) construct artificial islets attractive to gulls and inaccessible to stray dogs.

Breeding ecology of the Bare-Faced Ibis (Phimosus infuscatus) in Southern Brazil

The Bare-faced Ibis is a gregarious bird found in South America. In the face of a rapid expansion in a southern state in Brazil and a lack of detailed information about the species' reproduction, two breeding areas were studied weekly for two consecutive seasons. We registered numbers and characteristics of adults, nests, eggs, and chicks, calculated success estimates, and assessed nest installation preferences. Chick morphology, age, and measurements served to define five growth stages. The species used the margins of two close rivers in Santa Catarina to build nests, lay eggs, and develop parental care between August and January, with success estimates as expected for the family. We observed a preference for the eastern margin of the rivers and proximity to bridges for nest installation, where the muddy margin provides resources for juvenile feeding. Two colony models were defined based on the near or far installation of the nests. Variations in egg and chick dimensions indicated higher adult investment in the second season, with negative allometric growth of the bill and tarsus of chicks related to weight. The results presented suggest favorable conditions for the species’ reproduction in the region, a considerable factor in understanding its expansion in recent years.

Effects of hydrogen peroxide-induced oxidative stress on the plasma concentration and pharmacokinetics of ketorolac in chicks

The aim was to determine the impact of oxidative stress (OS), induced by hydrogen peroxide (H2O2), on the ketorolac plasma concentration and pharmacokinetics in the chicks. A significant decrease was observed in the total antioxidant status (TAS) measured on day 7th, 10th, and 14th of chicks age by 39, 29, and 41%, respectively compared to the control (H2O) group. By measuring the analgesic median effective dose (ED50), ketorolac’s analgesia amplified 16% in the stressed (H2O2) group. Ketorolac concentration in plasma was investigated at measured multiple times at 0.25, 0.5, 1, 2, 4, and 24 hours after the administration (14 mg/kg, IM) to 110.38, 181.46, 66.24, 13.08, 10.11, and 4.12 µg/ml at the H2O group and significantly elevated in all times measured except 0.25 and 24 h after ketorolac administration by 24, 38, 54, 199, 93, and 59 % to be 136.45, 250.88, 102.03, 39.13, 19.55, and 6.55 µg/ml in the H2O2 group, respectively. The values of AUC0-∞, AUMC0-∞, Cmax, and Kel in the stressed chickens that were administered ketorolac were elevated by 59, 19, 38, and 43%, respectively, whereas other parameters like MRT, t1/2β, Vss, and Cl were reduced by 25, 30, 56, and 37% respectively compared to H2O group. The results showed that the H2O2-inducedOS amplified the analgesic action of ketorolac in a chick model, besides its modification of the plasma concentration and pharmacokinetics of ketorolac.

Influence of In Ovo Leptin Injection into Yolk Sac on Embryo Development, Blood Biochemical Parameters and Lipid Metabolism of Broiler Chicks during Early Post-Hatching Period

The study aimed to investigate the effect of in ovo (IO) leptin injection on yolk sac leptin concentration, embryo development, blood lipid metabolism, and biochemical parameters of broiler chicks during the early post-hatching period. Hatching eggs were weighed and placed in an incubator with 100 eggs/4 replications/group. The groups were: non-injected group (C); and 3 injected groups with 100 μl of phosphate buffer solution (PBS); 0.5 μl leptin (L0.5), and 1 μl leptin (L1) in 100 μl of PBS. Pure leptin hormone dissolved in PBS was injected into the yolk sac on day 7 of incubation. Yolk/yolk sac leptin concentrations at the onset of incubation, on days 7 and 15 of incubation, and at hatching were determined. Embryo/chick development was determined at all ages. Serum leptin, tri-iodothyronine (T3), thyroxine (T4), creatine kinase, total protein, uric acid, and lipid profiles were measured at hatching and day 7 of chick age. The leptin level of the yolk was similar to the leptin level of the yolk sac at hatching. Leptin level of a yolk sac was higher on 7th day than at other ages. IO injection* age was significant for serum leptin level, which was similar to one-day chicks in the L0.5 at day 7 of chick age. T3, T4, creatine kinase, uric acid, lipid profiles, and embryo/chick development did not change with IO leptin. Serum HDL level was higher in the leptin groups than C and PBS groups at hatching. IO leptin application affects blood lipid metabolism depending on dose level for male broiler chicks at the early post-hatch period, without affecting embryo/chick development.Leptin level of yolk was similar to leptin level of yolk sac at hatching. Leptin level of yolk sac was higher on 7th day than other ages. IO injection* age was significant for serum leptin level, which was similar to one-day chicks in the L0.5 at day 7 of chick age. T3, T4, creatine kinase, uric acid, lipid profiles, and embryo/chick development did not change with IO leptin. Serum HDL level was higher in the leptin groups than C and PBS groups at hatching. IO leptin application affects blood lipid metabolism depending on dose level for male broiler chicks at early post-hatch period, without affecting embryo/chick development.

Evaluation of adding commercial compound Mixoil to drinking water on the productive performance of broilers during summer in Iraq

This study was conducted in the poultry field of the Department of Animal Production, Faculty of Agriculture, University of Kufa, for the period from September 2, 2021 to October7, 2021, and for a period of 5 weeks. In this study, 300 unsexed broiler chicks, Ross308 hybrid one day old, were randomly distributed to five treatments, each treatment included 60 chicks, three replicates, and each replicate included 20 chicks. The treatments were as follows: Treatment (T1): (control) was given water without addition, treatment (T2): drinking water was given to it with an addition of 0.25 ml/liter of the commercial compound (Mixoil) for 6 hours, treatment (T3). Provide her with drinking water with 0.5 ml/L of the commercial compound (Mixoil) for 6 hours. Treatment (T4): she was given drinking water with 0.75 ml/L of the commercial compound (Mixoil) for 6 hours, treatment (T5): she was given drinking water to which it was added 1 ml/L of the commercial compound (Mixoil) for 6 hours. Water was added to the commercial Mixoil compound daily from 10 am to 4 pm (6 hours per day), the chicks were fed on two diets, a starter during 21 days of age and a final from 22 days of age until the age of marketing (35 days), some productive traits were studied. for broilers during the duration of the experiment. The results of the statistical analysis indicated that there was a The research did not deal with blood traits, so this sentence should be deleted .The results of the statistical analysis indicated a significant improvement at the level (p≤0.05) in the average live body weight at the fifth week of chick age and in the total weight gain of the treated birds that added different levels of the commercial compound Mixoil daily to their drinking water compared to the control group. T1), The results also indicated a significant increase (p≤0.05) in the average total feed consumption for the birds of the fourth and fifth treatments compared with the control group, and a significant deterioration in the values of the total feed conversion ratio for the chicks of the control group (T1) compared with treatments T2 and T3.We conclude from the current study that adding different levels of the commercial compound Mixoil to drinking water for 6 hours a day had a positive effect in improving some productive traits of broiler chicks bred in summer in Iraq.

Vocal traits of shorebird chicks are related to body mass and sex

Acoustic communication is critical during early life phases in precocial birds; for example, adult alarm calls can elicit antipredator behaviour in young, and chick vocalizations can communicate information to parents about chick identity, condition, location, sex or age. We opportunistically recorded Red‐capped Plover Charadrius ruficapillus and Southern Masked Lapwing Vanellus miles novaehollandiae distress calls of chicks while they were in the hand and analysed the calls to determine whether call structure is related to sex or body mass (a proxy for age). Our study provides the first evidence for charadriid chicks of (1) a sexual difference in call structure and rate and (2) gradual growth‐related changes in call structure and rate, across chicks. We provide a foundation for further studies of shorebird vocalizations during growth, which may elucidate the development and functional significance of such vocalizations.

Behavioural adjustments in the social associations of a precocial shorebird mediate the costs and benefits of grouping decisions.

Animals weigh multiple costs and benefits when making grouping decisions. The cost‐avoidance grouping framework proposes that group density, information quality and risk affect an individual’s preference for con or heterospecific groups. However, this assumes the cost–benefit balance of a particular grouping is constant spatiotemporally, which may not always be true. Investigating how spatiotemporal context influences grouping choices is therefore key to understanding how animals contend with changing conditions.Changes in body size during development lead to variable conditions for individuals over short time‐scales that can influence their ecological interactions. Hudsonian godwits Limosa haemastica, for instance, form a protective nesting association with a major predator of young godwit chicks, colonial short‐billed gulls Larus brachyrhynchus. Godwit broods may avoid areas of higher gull densities when chicks are susceptible to gull predation but likely experience higher risk from alternative predators as a result. Associating with conspecifics could allow godwits to buffer these costs but requires enough other broods with whom to group.To determine how age‐dependent predation risk and conspecific density influence godwit grouping behaviours, we first quantified the time‐dependent effects of con‐ and heterospecific interactions on the mortality risk for godwit chicks throughout development. We then determined how godwit density and chick age affected their associations with con‐ and heterospecific.We found that younger godwit chicks' survival improved with closer association with conspecifics, earlier hatch dates and lower gull densities, whereas older chicks survived better with earlier hatch dates, though this effect was less clear. Concomitantly, godwit broods avoided gulls early in development and when godwit densities were high but maintained loose associations with conspecifics throughout development.We identified how individuals can optimally shift with whom they group according to risks that vary spatially and temporally. Investigating the effects of a species' ecological interactions across spatiotemporal contexts in this way can shed light on how animals adjust their associations according to the costs and benefits of each association.

Live weight performance of three different breed of indonesian local chickens in starter phase

The production of local chickens in Indonesia is determined by the availability of high-quality local chicken stocks. However, information on local chicken performance is limited, therefore, this study aims to determine the live weight performance of three local Indonesian chicken namely Merawang, Murung Panggang, and KUB in the starter phase. The study was conducted at chicken farm located in Semanu Gunung Kidul, Yogyakarta. Meanwhile, the live weight data were collected at the starter phase (0, 2, and 4 weeks. The samples consisted of 196 Merawang, 157 Murung Panggang, and 416 KUB chickens reared in a battery cage in a closed house under similar conditions. Furthermore, the live weight performance data were analyzed using analysis of variance (ANOVA). As a result, the Merawang chicken had the highest live weight (P<0.05) at the day-old chick (DOC) age. At the same age, no significant difference was detected between the KUB and Murung Panggang chicken (P>0.05). However, the live weight of Murung Panggang was significantly higher at 2 and 4 weeks compared to others (P< 0.05). Therefore, it was concluded that there are variations in the live weight of the three local chickens during the starter phase.

Interfere of maternal derived antibodies in early age of chicks with the efficacy of vaccination against Avian Influenza viruse.

Interfere of maternal derived antibodies in early age of chicks with the efficacy of vaccination against Avian Influenza viruse.

SURVIVAL POTENTIAL OF STRESSED CHICKS

Two hundred and forty broiler, cockerel and pullet chicks were deprived feeds, water brooder heat or combination of these to stimulate similar careless or accidental farm situations so as to find their effect on the chicks survival.The type of bird as well as brooder heat had no significant effect (P&gt;0.05) respectively on survival of chicks exposed to starvation stress, Age of chicks and nature of starvation significantly affected chicks survival. condition. A significant (P&lt;0.05) mortality rate was recorded at ages 4 and 5 days. The maximum and evening to monitor the room temperature survival duration was 8 days for all stress chicks. Those deprived of only water survived significantly (P &lt;0.05) longer than others. either feed, drinking water or both.

Auto-sexing potential and growth performance in Rhode Island, Nigerian local chickens and their reciprocal crosses

This study was conducted to determine auto-sexing potential in Rhode Island, Nigerian local chicken and their reciprocal crosses. A total of 241 eggs were set in the incubator to determine the fertility, hatchability, % Hatch, % dead in shell, % dead in cell and % deformed chicks in the four genotypes (Rhode Island Red (RIR) x Rhode Island White (RIW), Rhode Island Red (RIR) x Rhode Island White (RIW), Nigerian Local Red (NLR) x Rhode Island White (RIW) and Nigerian Local Red (NLR) x Nigerian Local White (NLW). Only 94 eggs were hatched. RIRXRIW crossbred chicks had the highest percentage fertility of 88.89% followed by RIRxRIW (86.27%), NLRXRIW (77.36%) and NLRxNLW (72.31%), respectively. RIRxNLW had the highest percentage hatchability of 65.19%, followed by RIRxRIW (51.56%), NLRxNLW (51.06%) and NLRxRIW (24.39%). It was observed in the hatch-out analysis that the cross between NLRxRIW had the highest percentage of dead in shell (29.27%) followed by RIRxRIW (17.19%), NLRxNLW (17.02%) and RIRxNLW (11.36%), respectively. The highest percentage of dead in cell was recorded in NLRxRIW crossbred (43.33%), followed by NLRxNLW (31.92%), RIRxRIW (28.13%) and RIRxNLW (15.91%). The observed deformed chicks were highest in NLRxNLW (20.85%) followed by RIRxNLW (10.34%), RIRxRIW (6.06%) and NLRxNLW (0%), respectively. Also observed was the occurrence of bangers with NLRxRIW, having the highest occurrence of bangers (9.08%) and with NLRxNLW having no occurrence of bangers. The records of weekly body weight were taken on the 94 chicks and chi square analysis was used to test colour inheritance of chicks. Significant (P&lt;0.05) difference was observed among genotypes in body weight of chicks at hatch and from weeks 1 to 8 weeks of age. The observed changes on body weight from 0 to 8th week of age of chicks showed significant difference across the four different genetic crossed groups (P&lt;0.05) and weight at the 8th week showed that the cross between RIRxRIW (216.93g) had better in growth as compared to the cross between NLRxRIW (202.75g) and NLRxNLW (193.17g) which were statistically similar (P&gt;0.05) and RIRxNLW (179.75g) crossbred chicks which had the lowest bodyweight at 8 weeks of age. The chi square (X2) analysis revealed that both RIRxRIW and NLRxRIW crossbred chicks were autosexed. The study concluded that selection for plumage colour showed great potential in determining the probability of chicks being autosexed. Also, pure bred of RIRXRIW and reciprocal cross of NLRXRIW showed great potential of producing autosexed chicks, while results on the direct crosses of NLRXNLW and RIRXNLW suggest that the pattern of inheritance of plumage colour is not simple. The study recommends further investigation to further ascertain the mode of plumage colour inheritance in the Nigerian Local Chickens.

Similar foraging energetics of two sympatric albatrosses despite contrasting life histories and wind-mediated foraging strategies.

Understanding the environmental and behavioral factors that influence how organisms maintain energy balance can inform us about their potential resiliency to rapid environmental changes. Flexibility in maintaining energy balance is particularly important to long-lived, central-place foraging seabirds that are constrained when locating food for offspring in a dynamic ocean environment. To understand the role of environmental interactions, behavioral flexibility and morphological constraints on energy balance, we used doubly labeled water to measure the at-sea daily energy expenditure (DEE) of two sympatrically breeding seabirds, Campbell (Thalassarche impavida) and grey-headed (Thalassarchechrysostoma) albatrosses. We found that species and sexes had similar foraging costs, but DEE varied between years for both species and sexes during early chick rearing in two consecutive seasons. For both species, greater DEE was positively associated with larger proportional mass gain, lower mean wind speeds during water take-offs, greater proportions of strong tailwinds (>12 m s-1), and younger chick age. Greater proportional mass gains were marginally more costly in male albatrosses that already have higher wing loading. DEE was higher during flights with a greater proportion of strong headwinds for grey-headed albatrosses only. Poleward winds are forecasted to intensify over the next century, which may increase DEE for grey-headed albatrosses that heavily use this region during early chick rearing. Female Campbell albatrosses may be negatively affected by forecasted slackening winds at lower latitudes due to an expected greater reliance on less energy efficient sit-and-wait foraging strategies. Behavioral plasticity associated with environmental variation may influence future population responses to climate change of both species.

Plumage development and environmental factors influence surface temperature gradients and heat loss in wandering albatross chicks.

Young birds in cold environments face a range of age-specific thermal challenges. Studying the thermal biology of young birds throughout ontogeny may further our understanding of how such challenges are met. We investigated how age and environmental parameters influenced surface temperature gradients across various body regions of wandering albatross (Diomedea exulans) chicks on Bird Island, South Georgia. This study was carried out over a 200d period during the austral winter, from the end of the brood-guard period until fledging, bridging a gap in knowledge of surface temperature variation and heat loss in developing birds with a long nestling stage in severe climatic conditions. We found that variation in surface temperature gradients (i.e. the difference between surface and environmental temperature) was strongly influenced by chick age effects for insulated body regions (trunk), with an increase in the surface temperature gradient that followed the progression of plumage development, from the second set of down (mesoptiles), to final chick feathers (teleoptiles). Environmental conditions (primarily wind speed and relative humidity) had a stronger influence on the gradients in uninsulated areas (eye, bill) than insulated regions, which we interpret as a reflection of the relative degree of homeothermy exhibited by chicks of a given age. Based on biophysical modelling, total heat loss of chicks was estimated to increase linearly with age. However, mass specific heat loss decreased during the early stages of growth and then subsequently increased. This was attributed to age-related changes in feather growth and activity that increased surface temperature and, hence, metabolic heat loss. These results provide a foundation for further work on the effects of environmental stressors on developing chicks, which are key to understanding the physiological responses of animals to changes in climate in polar regions.

Lizard provisioning and breeding success of kestrels inhabiting an island xeric environment

Parental provisioning and breeding success of Eurasian Kestrel (Falco tinnunculus) has been widely studied in some continental populations but not in their island-dwelling counterparts. We studied breeding success of kestrels nesting in natural rocky cavities in southern xerophytic scrub of the oceanic island of Tenerife during eight breeding seasons and its relationships with the endemic Gallot's Lizard (Gallotia galloti). We examined lizard provisioning to assess some hypotheses regarding parental provisioning (e.g. central place foraging, parental investment and territory quality). Kestrels nesting in better quality territories (i.e. better habitats for lizards) advanced laying date and increased clutch and brood size at hatching. This did not result in higher number of fledglings. Lizard biomass provided to the chicks did not decrease with increasing nestling age and was correlated positively with the number of nestlings and chick age. These findings support the hypothesis of parental investment. On considering nestling-rearing period in three 10-day phases, we found significantly lower mean mass of lizards delivered in the first phase than in the other two phases together, with no differences between the last two phases. We suggest that kestrels respond to enhance breeding success and fitness keeping a stable number and quality of fledglings.

Efficacy of The Turkey Herpes virus-IBDV Vector Vaccine Against Recent Egyptian Very Virulent IBDV in Commercial Layers

The infectious bursal disease virus (IBDv) is widespread in poultry flocks all around the world. During the period between 2016- 2017, 22 IBD outbreaks were investigated in El-Minoufiya Governorate in different chicken sectors (11 broilers, 7 commercial layer pullets and 4 native baladi varieties). The disease occurred at 23-42 days of age. The mortality ranged between 3-9 % in commercial broilers farms, 5.8-12% in native breed varieties and 5-10 % in commercial layer replacement pullets. Two hundred one-day-old commercial male layer chicks was used for assessment of protection obtained after vaccination with HVT-IBDV vector vaccine Vaxxitek against challenged with vvIBDV local field isolate Lay./Men.Egypt/17 at 46th-day of age. Maternal derived antibodies (MDA) was followed up by ELISA to determine MA waning and the suitable age of chicks for IBDV vaccination and/or challenge. Chicks divided into 4 groups of (50 birds/ of each), G1 (vaccinated with HVT-IBD vector vaccine at 1 day old of age and non-challeneged) and G2 (vaccinated with HVT-IBDV at one-day of age and challenged with vvIBDV local field isolate Lay./Men.Egypt/017 at 46-day of age), G3 (non- vac-cinated and non-challenged) and G4 (non-vaccinated and challenged chickens). Our results revealed that the mortality percentage of commercial male layer chickens chal-lenged with recent vvIBDV local field isolate lay./Men.Egypt/017 was (0%) in G2, while in G4 was (90%), at 7-days post challenge. The highest bursa body ratio observed was (5.32 and 5.31) in non- vaccinated and non-challenged birds (G3) and birds vac-cinated with the VAXXITEK HVT-IBDv vaccine (G1). Conclusion, the recombinant VAXXITEK HVT-IBDv vaccine has provided protection for commercial male layer chicks against challenge with recent vvIBDv isolate. Vaccination with vector vaccine in en-demic areas with vvIBDV, protect against mortality, partially against bursal atrophy and decreases immunosuppressive effect of vvIBDV.

Fuzzy prediction and pattern analysis of poultry egg production

Egg production is geared towards large scale production of eggs for profit maximization and consumption. But poultry farmers are faced with challenges that affect the quantity and quality of egg production during the production life cycle such as quality of feed intake, management issues, genetic factors of the breed birds, age at egg laying period, presence of diseases, molting flock, housing and others. Several mechanical solutions have been suggested to implement the production cycle but with very high cost implication which calls for the need of soft computing methods to model the egg production process. However, modelling egg production curve is a complex task because a typical egg production curve (from week 20 to week 72) is characterized by nonlinear probabilities and imprecise knowledge in the egg production process. This paper proposes an optimal fuzzy predictive model for poultry egg production. The motivation stems from analyzing the non-linearity and imprecision in egg production which is best handled by fuzzy logic as compared to other soft computing techniques. Data samples were collected on the age of chicks, quantity of feeds, quality of feeds, body weight of chicks and total egg production as input into the proposed system. The first stage of implementation is carried out in the Statistical Package for Social Science (SPSS) software environment to perform correlation analysis while the last two stages are carried out using Fuzzy Toolbox in MATLAB based on its capability to model and simulate complex systems with robust and interpretable predictions. Gaussian membership function was used in the fuzzification process while Mamdami structure was adopted as the fuzzy inference system (FIS). Model performance evaluation showed that the proposed system performed excellently by achieving best prediction accuracy 100% Pred(30) with an approximate mean magnitude relative error (MMRE) of 0.11744 as compared to the results in the reported literature. The method has proven to be a cost-effective and simple approach to modelling through the use of samples and parameters from poultry house.

Chick growth and nutrient requirement during rearing period on eclectus parrot (Eclectus roratus, Müller 1776)

Nutrition is an important aspect of the successful breeding of wild birds in captivity. This research aims to find out nestling growth of Eclectus parrot (Eclectus roratus, Müller 1776) by parent-reared and nutrient requirement during rearing season. This research used a pair of Eclectus parrot with a male chick at first and fifth clutch, and female chick at the second, third, and fourth clutch. This research was conducted from July 2016 to June 2018. The bodyweight of chick was measured every week and feed intake was observed since the age of one week until the chick can eat independently. Feed was provided ad libitum and cafeteria. The chick was the altricial type. Feathers began to cover all bodies at weeks 9. Fledging time was approximately at weeks 10-11. Chick could be separated from its parents at 20 weeks of age. Feed intake tends to be increased along with the increasing age of chick. Eclectus favorites feed is sunflower seed. Nutrient consumption when rearing male chick is more than rearing the female chick.

Extreme offspring ornamentation in American coots is favored by selection within families, not benefits to conspecific brood parasites

Offspring ornamentation typically occurs in taxa with parental care, suggesting that selection arising from social interactions between parents and offspring may underlie signal evolution. American coot babies are among the most ornamented offspring found in nature, sporting vividly orange-red natal plumage, a bright red beak, and other red parts around the face and pate. Previous plumage manipulation experiments showed that ornamented plumage is favored by strong parental choice for chicks with more extreme ornamentation but left unresolved the question as to why parents show the preference. Here we explore natural patterns of variation in coot chick plumage color, both within and between families, to understand the context of parental preference and to determine whose fitness interests are served by the ornamentation. Conspecific brood parasitism is common in coots and brood parasitic chicks could manipulate hosts by tapping into parental choice for ornamented chicks. However, counter to expectation, parasitic chicks were duller (less red) than nonparasitic chicks. This pattern is explained by color variation within families: Chick coloration increases with position in the egg-laying order, but parasitic eggs are usually the first eggs a female lays. Maternal effects influence chick coloration, but coot females do not use this mechanism to benefit the chicks they lay as parasites. However, within families, chick coloration predicts whether chicks become "favorites" when parents begin control over food distribution, implicating a role for the chick ornamentation in the parental life-history strategy, perhaps as a reliable signal of a chick's size or age.

Time and energy costs of different foraging choices in an avian generalist species

BackgroundAnimals can obtain a higher foraging yield by optimizing energy expenditure or minimizing time costs. In this study, we assessed how individual variation in the relative use of marine and terrestrial foraging habitats relates to differences in the energy and time investments of an avian generalistic feeder (the Lesser Black-backed Gull, Larus fuscus), and how this changes during the course of the chick-rearing period.MethodsWe analyzed 5 years of GPS tracking data collected at the colony of Zeebrugge (Belgium). Cost proxies for energy expenditure (overall dynamic body acceleration) and time costs (trip durations and time spent away from the colony), together with trip frequency, were analyzed against the relative use of the marine and terrestrial habitats.ResultsThe marine habitat was most often used by males and outside weekends, when fisheries are active. Marine trips implied higher energetic costs and lower time investments. As chicks became older, terrestrial trips became more prevalent, and trip frequency reached a peak towards 20 days after hatching of the first egg. Over a full chick rearing period, energy costs varied widely between individuals, but no trends were found across the marine foraging gradient. Conversely, a higher use of marine foraging implied lower overall amounts of time spent away from the colony.ConclusionsForaging habitat choice was related to overall time costs incurred by gulls, but not to energy costs. The effect of chick age on foraging habitat choice and effort may be driven by energy expenditure constraints on the amount of marine foraging that can be performed. If time is less constraining to them, Lesser Black-backed Gulls may meet the increasing chick demand for food by switching from high to low energy demanding foraging strategies.

Mismatches between breeding phenology and resource abundance of resident alpine ptarmigan negatively affect chick survival.

Phenological mismatches—defined here as the difference in reproductive timing of an individual relative to the availability of its food resources—occur in many avian species. Mistiming breeding activities in environments with constrained breeding windows may have severe fitness costs due to reduced opportunities for repeated breeding attempts. Therefore, species occurring in alpine environments may be particularly vulnerable.We studied fitness consequences of timing of breeding in an alpine‐endemic species, the white‐tailed ptarmigan (Lagopus leucura), to investigate its influence on chick survival. We estimated phenological mismatch by measuring plant and arthropods used by ptarmigan in relation to their timing of breeding.We monitored 120 nests and 67 broods over a three‐year period (2013–2015) at three alpine study sites in the Rocky Mountains of Colorado. During this same period, we actively monitored food resource abundance in brood‐use areas to develop year and site‐specific resource phenology curves. We developed several mismatch indices from these curves that were then fit as covariates in mark‐recapture chick survival models.A correlation analysis between seasonal changes in arthropod and food plant abundance indicated that a normalized difference vegetation index (NDVI) was likely the best predictor for food available to hens and chicks. A survival model that included an interaction between NDVI mismatch and chick age received strong support and indicated young chicks were more susceptible to mismatch than older chicks.We provide evidence that individual females of a resident alpine species can be negatively affected by phenological mismatch. Our study focused on individual females and did not examine if phenological mismatch was present at the population level. Future work in animal populations occurring in mountain systems focusing on a combination of both individual‐ and population‐level metrics of mismatch will be beneficial.