  A wide class of scalar field models including Quintessence and K-essence have
the attractive property of tracker regimes, where the energy density stored in
the field evolves so as to mimic that of the dominant background component for
a period of time. During this evolution, for a brief period of time there is an
increase in the energy density of the field as it spirals in towards it's
attractor solution. We show that when the peak of this energy density occurs
around the epoch of equality, we can address a key requirement of early dark
energy (EDE), postulated as a solution to the Hubble tension. In particular we
demonstrate how this can occur in a wide class of Quintessence, axion and
K-essence models, before showing that the Quintessence models suffer in that
they generally lead to sound speeds incompatible with the requirements of EDE,
whereas the K-essence and axion models can do a better job of fitting the data.
