Hoopoe Larks Research Articles

Impact of chlorpyrifos used for desert locust control on non-target organisms in the vicinity of mangrove, an ecologically sensitive area

Ecologically sensitive areas (ESAs) including the mangrove along the Red Sea Coast of Sudan may be subjected to adverse impacts of insecticides for controlling desert locust, Schistocerca gregaria (Acrididae). This study assessed potential impacts of an aerial application of chlorpyrifos (Ultra Low Volume [ULV], 279 g a.i. ha−1) during conditions resembling an operational treatment of desert locust. The surveyed non-target organisms were studied in one treated and one untreated area (88 ha each), during a 13-week pre-spray period and an 8-week post-spray period, from November 2001 to April 2002. Survival of caged prawns (Penaeidae) in the mangrove lagoon were tested in situ, and monitoring of relative abundances of non-target organisms included (i) terrestrial transect counts of hoopoe larks, Alaemon alaudipes (Alaudidae), and of antlion larval pits, Cueta spp. (Myrmeleontidae) and (ii) pitfall sampling of epigeal arthropods in the terrestrial zones from shore to cropland. The survival of Metapenaeus monoceros juvenile prawns fell dramatically between the third and fifth day after the application in the treated area compared to the untreated area, in which mortality was delayed. In the early mornings when control operations often occur, a northern and northwestern wind direction, i.e. from land towards the sea, dominates, thus adverse impact on the prawns is a risk. The abundance of antlion pits was reduced in the treated area following spraying, but not in the untreated. The same was true for observations of hoopoe larks, numbers of Mesostena angustata (Tenebrionidae), and Gryllus bimaculatus (Gryllidae), at species and family levels, and arachnids.

NEST SITE SELECTION IN A HOT DESERT: TRADE-OFF BETWEEN MICROCLIMATE AND PREDATION RISK?

Abstract Nest placement affects the risk of predation on both eggs and incubating parents and determines the microclimate for incubation, two functions that may be in conflict, especially in hot deserts. We studied the roles of microclimate and nest predation on nest site selection by Hoopoe Larks (Alaemon alaudipes) in the Arabian Desert. Hoopoe Larks build nests in three microsites: on the gravel plain away from vegetation, at the base of bushes, or above ground in bushes. Early in the breeding season, 70% of nests were placed on the ground, but as the season progressed, nests in small bushes represented 77% of total nests; nest cover increased from 5% to 21%. Daily survival rate of natural nests was 0.82. Predation on eggs did not differ among nest sites, either for natural nests or in an experiment with artificial nests. Measurements of operative and egg temperatures showed that artificial nests on the gravel plain experience higher temperatures than those under and in bushes. Nest attendance totaled ...

Variation in allocation of time, water and energy in Hoopoe Larks from the Arabian Desert

Summary Patterns of resource allocation in different times of the year can provide insights into the effects of simultaneous environmental constraints on reproduction and survival of desert birds. Field metabolic rate (FMR), water influx rate (WIR) and patterns of time allocation of Hoopoe Larks (Alaemon alaudipes Desfontaines) were investigated during spring, when larks were rearing offspring, and during summer, presumably the harshest time for desert birds, in the Arabian Desert. FMR was 45% below allometric predictions in spring (1·83 times basal metabolic rate, BMR) and 58% below predictions in summer (1·37 times BMR). WIR was 37% lower than predicted during the nestling period and 55% lower than predicted during summer. Activity patterns during spring and summer were bimodal, with birds foraging in the early morning and late afternoon and resting in the shade or attending the nest during midday. Foraging time was similar in spring (32·0% of total daytime) and summer (33·6% of total daytime), despite higher energy and water intakes for parents and offspring in spring, suggesting that food availability was higher in spring. The non‐foraging time was entirely spent resting in summer, while in spring half of this time was allocated to caring for offspring and the other half to resting in the shade. Hoopoe Larks fed their offspring 55 times per day and shaded their chicks about 5 h per day to protect them from solar radiation. High Tas combined with low and unpredictable food availability in deserts may constrain reproduction by limiting the amount of time, water and energy that parents can devote to rearing offspring.

PHENOTYPIC VARIATION OF LARKS ALONG AN ARIDITY GRADIENT: ARE DESERT BIRDS MORE FLEXIBLE?

We investigated interindividual variation and intra-individual phenotypic flexibility in basal metabolic rate (BMR), total evaporative water loss (TEWL), body temperature (Tb), the minimum dry heat transfer coefficient (h), and organ and muscle size of five species of larks geographically distributed along an aridity gradient. We exposed all species to constant environments of 15°C or 35°C, and examined to what extent interspecific differences in physiology can be attributed to acclimation. We tested the hypothesis that birds from deserts display larger intra-individual phenotypic flexibility and smaller interindividual variation than species from mesic areas. Larks from arid areas had lower BMR, TEWL, and h, but did not have internal organ sizes different from birds from mesic habitats. BMR of 15°C-acclimated birds was 18.0%, 29.1%, 12.2%, 25.3%, and 4.7% higher than of 35°C-acclimated Hoopoe Larks, Dunn's Larks, Spike-heeled Larks, Skylarks, and Woodlarks, respectively. TEWL of 15°C-acclimated Hoopoe Larks exceeded values for 35°C-acclimated individuals by 23% but did not differ between 15°C- and 35°C-acclimated individuals in the other species. The dry heat transfer coefficient was increased in 15°C-acclimated individuals of Skylarks and Dunn's Larks, but not in the other species. Body temperature was on average 0.4°C ± 0.15°C (mean ± 1 sem) lower in 15°C-acclimated individuals of all species. Increased food intake in 15°C-acclimated birds stimulated enlargement of intestine (26.9–38.6%), kidneys (9.8–24.4%), liver (16.5–27.2%), and stomach (22.0–31.6%). The pectoral muscle increased in 15°C-acclimated Spike-heeled Larks and Skylarks, remained unchanged in Hoopoe Larks, and decreased in 15°C-acclimated Woodlarks and Dunn's Larks. We conclude that the degree of intra-individual flexibility varied between physiological traits and among species, but that acclimation does not account for interspecific differences in BMR, TEWL, and h in larks. We found no general support for the hypothesis that species from desert environments display larger intra-individual phenotypic flexibility than those from mesic areas. The coefficient of variation of larks acclimated to their natural environment was smaller in species from arid areas than in species from mesic areas for mass-corrected BMR and surface-specific h, but not for mass-corrected TEWL. The high repeatabilities of BMR, TEWL, and h in several species indicated a within-individual consistency on which natural selection could operate.

Cutaneous and respiratory water loss in larks from arid and mesic environments.

Birds from deserts generally have lower total evaporative water loss (TEWL), the sum of cutaneous (CWL) and respiratory water loss (RWL), than species from mesic areas. We investigated the role of CWL and RWL as a function of air temperature (T(a)) in hoopoe larks (Alaemon alaudipes) and Dunn's larks (Eremalauda dunni) from the Arabian Desert and skylarks (Alauda arvensis) and woodlarks (Lullula arborea) from temperate mesic grasslands. The proportional contribution of CWL to TEWL in all larks at moderate T(a) ranged from 50% to 70%. At high T(a) (40 degrees -45 degrees C), larks enhanced CWL by only 45%-78% and relied on an increase in RWL by 676%-2,733% for evaporative cooling. Surface-specific CWL at 25 degrees C was 29% lower in the arid-zone species than in the mesic larks. When acclimated to constant T(a), 15 degrees C-acclimated hoopoe larks increased CWL by 22% compared with 35 degrees C-acclimated birds, but the other species did not change CWL. This study is consistent with the hypothesis that larks from deserts have a reduced CWL at moderate and low T(a) but provided no support for the hypothesis that at high T(a) larks from arid regions rely more on CWL than larks from mesic environments. Interspecific differences in CWL cannot be attributed to acclimation to environmental temperature and are possibly the result of genetic differences due to natural selection or of phenotypically plastic responses to divergent environments during ontogeny.

Physiological adjustments to arid and mesic environments in larks (Alaudidae).

Because deserts are characterized by low food availability, high ambient temperature extremes, and absence of drinking water, one might expect that birds that live in these conditions exhibit a lower basal metabolic rate (BMR), reduced total evaporative water loss (TEWL), and greater ability to cope with high air temperatures than their mesic counterparts. To minimize confounding effects of phylogeny, we compared the physiological performance of four species of larks at ambient temperatures (T(a)'s) ranging from 0 degrees to 50 degrees C: hoopoe larks (Alaemon alaudipes) and Dunn's larks (Eremalauda dunni) live in hot and dry deserts, whereas skylarks (Alauda arvensis) and woodlarks (Lullula arborea) occur in temperate mesic areas. Mass-adjusted BMR and TEWL were indistinguishable between hoopoe lark and Dunn's lark and between skylark and woodlark. When grouping the data of the two desert larks in one set and the data of the two mesic larks in another, desert larks are shown to have 43% lower BMR levels and 27% lower TEWL values than the mesic species. Their body temperatures (T(b)'s) were 1.1 degrees C lower, and the minimal dry heat transfer coefficients (h) were 26% below values for the mesic larks. When T(a) exceeded T(b), the h of hoopoe larks and Dunn's larks was high and indistinguishable from h at 40 degrees C, in contrast to the prediction that h should be decreased to minimize heat gain through conductance, convection, or radiation from the environment when T(a) exceeds T(b).

Ecological and Evolutionary Physiology of Desert Birds: A Progress Report

The adaptive significance of mechanisms of energy and water conservation among species of desert rodents, which avoid temperature extremes by remaining within a burrow during the day, is well established. Conventional wisdom holds that arid-zone birds, diurnal organisms that endure the brunt of their environment, occupy these desert climates because of the possession of physiological design features common to all within the class Aves. We review studies that show that desert birds may have evolved specific features to deal with hot desert conditions including: a reduced basal metabolic rate (BMR) and field metabolic rate (FMR), and lower total evaporative water loss (TEWL) and water turnover (WTO).Previous work on the comparative physiology of desert birds relied primarily on information gathered on species from the deserts of the southwestern U.S., which are semi-arid habitats of recent geologic origin. We include data on species from Old World deserts, which are geologically older than those in the New World, and place physiological responses along an aridity axis that includes mesic, semi-arid, arid, and hyperarid environments.The physiological differences between desert and mesic birds that we have identified using the comparative method could arise as a result of acclimation to different environments, of genetic change mediated by selection, or both. We present data on the flexibility of BMR and TEWL in Hoopoe Larks that suggest that phenotypic adjustments in these variables can be substantial. Finally, we suggest that linkages between the physiology of individual organism and its life-history are fundamental to the understanding of life-history evolution.

Flexibility in basal metabolic rate and evaporative water loss among hoopoe larks exposed to different environmental temperatures.

The 'energy demand' hypothesis for short-term adjustments in basal metabolic rate (BMR) posits that birds adjust the size of their internal organs relative to food intake, a correlate of energy demand. We tested this hypothesis on hoopoe larks (Alaemon alaudipes), inhabitants of the Arabian desert, by acclimating birds for 3 weeks at 15 degrees C and at 36 degrees C, then measuring their BMR and total evaporative water loss (TEWL). Thereafter, we determined the dry masses of their brain, heart, liver, kidney, stomach, intestine and muscles of the pectoral region. Although mean body mass did not differ initially between the two groups, after 3 weeks, birds in the 15 degrees C group had gained mass (44.1+/-6.5 g), whereas larks in the 36 degrees C group had maintained a constant mass (36.6+/-3.6 g; means +/- s.d., N=6). Birds in the 15 degrees C group had a mean BMR of 46.8+/-6.9 kJ day(-1), whereas birds in the 36 degrees C group had a BMR of 32.9+/-6.3 kJ day(-1), values that were significantly different when we controlled for differences in body mass. When measured at 35 degrees C, larks in the cold-exposure group had a TEWL of 3.55+/-0.60 g H(2)O day(-)(1), whereas TEWL for birds in the 36 degrees C group averaged 2.23+/-0.28 g H(2)O day(-1), a difference of 59.2%. Mass-independent TEWL differed significantly between groups. Larks in the 15 degrees C group had a significantly larger liver, kidney and intestine than larks in the 36 degrees C group. The total increase in organ mass contributed 14.3% towards the total mass increment in the cold exposure group. Increased food intake among larks in the cold group apparently resulted in enlargement of some of the internal organs, and the increase in mass of these organs required a higher rate of oxygen uptake to support them. As oxygen demands increased, larks apparently lost more evaporative water, but the relationship between increases in BMR and TEWL remains unresolved.

Lizard Burrows Provide Thermal Refugia for Larks in the Arabian Desert

A common perception is that desert birds experience greater extremes of heat and aridity than their mammalian counterparts, in part, because birds do not use burrows as a refuge from the desert environment. We report observations of Dunn's Larks (Eremalauda dunni), Bar-tailed Desert Larks (Ammomanes cincturus), Black-crowned Finch Larks (Eremoprerix nigriceps), and Hoopoe Larks (Alaemon alaudipes) using burrows of the large herbivorous lizard Uromastyx aegypticus as thermal refugia during hot summer days in the Arabian Desert. Continuous recordings of shade air temperature (T-a), soil surface temperature (T-surface), burrow air temperature (Ta-burrow), and burrow substrate temperature (T-substrate) showed that T-surface exceeded 60 degrees C on most days. T-a typically exceeded 45 degrees C, whereas Ta-burrow was around 41 degrees C during midday. Calculations of total evaporative water loss at different temperatures indicated that Hoopoe Larks can potentially reduce their water loss by as much as 81% by sheltering in Uromastyx burrows during the hottest periods of the summer day.