Amphibians have much lower BMR and mass-specific BMR than birds

The "baseline" metabolic rate of an animal is measured as the basal metabolic rate (BMR) for an endotherm or as the standard metabolic rate (SMR) for an ectotherm. Endotherms tend to have basal high metabolic rates and high energy needs thanks to their maintenance of a constant body temperature. Ectotherms of similar size tend to have much lower standard metabolic rates and energy requirements, sometimes 10%, percent or less than those of comparable endotherms

Is the BMR and mass-specific BMR of amphibians higher, lower, or the same as it is in birds? The average body mass of birds and mammals is very different hence the much higher mass-specific BMR of birds, but the average body mass of amphibians and birds is much more similar. Does it mean the mass-specific BMRs of Birds and Amphibians are similar?

Are BMR and mass-specific BMR similar in amphibians and birds? The BMR and mas-specific BMR of Amphibians are much lower than the ones of birds. Endotherms (Birds) use metabolic heat to keep a stable body temperature, while ectotherms (Amphibians) do not. Amphibians have much lower energy requirements and therefore lower metabolic rates.

The study uses data extracted from Quaardvark and collected in Excel spreadsheet.

65 species of birds and 13 species of Amphibians are used in the study.

Data extracted from Quaardvark is exported to Excel and used to calculate average body mass, BMR, mass-specific BMR, and t-value for birds and amphibians. The relationship between the independent (body mass) and dependent (BMR and mass-specific BMR) is illustrated using scatterplot graphs and trend lines.

In birds, the body mass and BMR are directly proportional as shown in Table 1. The body mass and mass-specific BMR are inversely proportional as shown in Table 2. In Amphibians the body mass and BMR are directly proportional as shown in Table 3. while the body mass and mass-specific BMR are inversely proportional as shown in Table 4.

Figure 1. Relationship between Body mass (g) and BMR (W) in Birds. Figure 2. Relationship between Body mass (g) and mass-specific BMR (W/g) in Birds. Figure 3. Relationship between Body mass (g) and BMR (W) in Amphibians. Figure 4. Relationship between Body mass (g) and mass-specific BMR (W/g) in Amphibians. Figure 5. T-test Body mass of Birds vs Amphibians. Figure 6. T-test BMR Birds vs Amphibians. Figure 7. T-test Mass specific BMR of Birds vs Amphibians.

Table 1. T-test Body mass of Birds vs Amphibians. Table 2. T-test BMR Birds vs Amphibians. Table 3. T-test Mass specific BMR of Birds vs Amphibians.

BMR and mass-specific BMR of amphibians is much lower when compared to birds.

Amphibians are ectotherms and have much lower energy requirements than birds despite having the same directly proportional relationship between body mass and BMR and inversely proportional relationship between body mass and mass-specific BMR.

The average body mass of birds is much more similar to the average body mass of amphibians than it is to the average body mass of mammals. Their BMR and mass-specific BMR are, however, very different. Amphibians as ectotherms don't use metabolic heat to maintain body temperature therefore their energy requirements are very low as are their BMR and mass-specific BMR.

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(Auer et al. 2018)