The Bald Eagle can currently carry 4 pounds (1.81 kilograms for the real world) about 60 metres in a straight line (Snow, C. 1973. Habitat Management Series for Endangered Species. Bureau of Land Management Report No. 5. Southern Bald Eagle and Northern Bald Eagle. Technical Note TN-171.)
Average
weight of a newborn baby is 7 pounds (University of Utah Health Science Centre, 2001)
5 eagles can carry 20 pounds, or 9.07 kgs. We'll assume they can lift that the same length. Given that they would lift the object upwards, not being a physicist or indeed someone inclined to strain the lifting power of eagles to any length, we'll say that the eagles could lift in tandem the 20 pound object 30 metres upwards.
Given that by the end of the second year of a newborn's life they have quadrupled in weight, an average child would weigh 28 pounds. Diet has an effect on this of course, along with the racial and genetic make up of the child in question. But we're talking averages here.
(linky)
Anabolic steroids alone would see an increase in size, muscle mass and overall efficiency in the animals, however it is really a temporary measure and wouldn't significantly alter the avian for our purposes.
While I hesitate to mention selective breeding, it does appear to be the most overall efficient way to increase the size and capabilities of the avian involved without tampering hormonally or other such. To begin, I'll point out the difference between the almost pre-historic but still extant horse found in Mongolia (standing 128cm at the withers) and with the common Clydesdale horse (standing roughly two metres tall at the withers) - 36% larger than the Mongolian horse. We'll assume that the lifting/pulling capacity is at least increased by the same percentage, given that I was unable to find the stats for the Mongolian horse to compare with that of the Clydesdale. (Various sources. Have a look at google.)
Applying the same principle to the eagle, we could see an increase in its lifting capacity by 36% (approximately a third) given a selective breeding program and sufficient time. That would give a single eagle the lifting capacity of 2.5 kilograms (approx.) and the group of five eagles the lifting capacity of 10 kilograms, or approx. 28 pounds.
Why would anyone want larger eagles that can lift 2.5 kgs each?
Simple.
Ever been shopping, and behind you is that whining kid? You know the one. It screams. It begs. It whines. It demands lollies (or candy, given your nationality) or that Action Man figure. It squeals, grunts and otherwise makes a range of sounds commonly attributed to a pig being tortured or a kraken with constipation.
Ever been walking in the park, only to be harassed by something not so much a dog but a rat on a leash? The tiny thing yapping at you as if you have bacon in your pants (hey, who am I to judge if you do, right?) while the owner looks on fatuously at its yipping rodent with nothing but a beam on its face and the cry of the stupid "Ohinnitcute"?
The enlarged eagles are what you need. Given how well an eagle (and indeed other birds of prey) can be trained, wouldn't it be worth it to see the whining child carried to the top of a 30mtr building and left there by a majestic flock of enlarged eagles? Perhaps you'd like to see that little hairy rat taken far away - perhaps the big cat enclosure at your local zoo - never to pester you again?
We need less focus on such piddling little problems like cola wars and how many licks does it take to get to the centre of a tootsie roll. We need enlarged lifting eagles.