Why wavelength and frequency are two names for the same thing
For light traveling through a given medium, wavelength and frequency are locked together: multiply the two and you get the speed of light. So a wave with a shorter wavelength necessarily has a higher frequency, and vice versa. That is why asking whether color depends on wavelength or frequency is a bit like asking whether a person's height depends on centimeters or inches. The measurement changes, the underlying thing does not.
The supplied research treats the two as interchangeable handles on the same phenomenon. One study of Japanese quails describes red light as roughly 625–740 nm and, in the same breath, as roughly 480–405 THz [1]. Those are the same band of light written two ways: the nanometer figure is the wavelength, the terahertz figure is the frequency, and the paper pairs them as a single description of "red." That pairing is the clearest illustration in the evidence that color, wavelength, and frequency are not three separate things but one property described in different units.
How color gets pinned to a wavelength in practice
Devices that identify or reproduce color do so by working with wavelength. A silicon-based sensor distinguishes light across a broad range from 365 to 1080 nm by exploiting how differently silicon absorbs different wavelengths, and it can even pick out the color of a mixture of two wavelengths (540 and 620 nm) [4]. The sensor never measures "redness" directly; it measures wavelength, and color follows from that.
Color reproduction works the same way from the other direction. By tuning the frequencies and amplitudes of acoustic waves in a crystal, researchers could select which wavelengths of white light to let through and thereby build up a specific target color, covering almost the entire standard color space used to define colors precisely [2]. Here the control knob is frequency, but the thing being selected is wavelength, and the output is color. The two descriptions are inseparable in the apparatus itself.
Color is not fixed forever: it can be converted
Because color rides on frequency and wavelength, changing a light's frequency changes its color. One experiment converted incoming mid-infrared light, around 10 micrometers in wavelength, into visible light using molecular vibrations in tiny antenna structures [5]. The incoming light was far outside what we see; the outgoing light was visible. The mechanism is a frequency shift, and the visible result is a color change.
A related line of work describes quantum frequency conversion of light pulses between colors, with conversion rates approaching unity in theory [3]. The framing throughout is in terms of frequency, yet the practical outcome is light of a different color. This reinforces the main point: when researchers want to change a color, they change a frequency, and the wavelength moves with it.
A reminder that "color" means different things to different eyes
One study complicates the everyday assumption that color is a single fixed property. Japanese quails respond to red and green wavelengths differently than humans do, and the researchers interpret this as the birds being more sensitive to those bands [1]. The paper also reports that light wavelength appeared to influence the frequency of the birds' sounds, though that is a separate finding about bird behavior, not about the nature of light.
The useful takeaway for the color question is a caution about scope. When we say a wavelength "is" a color, we mean a color as defined by human vision or by a standard color space [2][4]. Other animals can have different sensitivity, so the same wavelength may register differently to them [1]. The physical link between wavelength and frequency is universal; the link between a wavelength and a perceived color is specific to the viewer.
Sources used in this answer
Interpretation of the relationship between the effects of different colors wavelength light application and sound frequency in japanese quails by spectral analysis
Red light is described simultaneously as roughly 625–740 nm and 480–405 THz, pairing wavelength and frequency as one description, and the study reports that light wavelength appeared to affect the frequency of quail sounds.
Color Reproduction by Multi-Wavelength Bragg Diffraction of White Light
Tuning acoustic-wave frequencies to select specific wavelengths of white light allowed precise reproduction of target colors across almost the full standard color space.
Quantum manipulation of two-color stationary light: Quantum wavelength conversion
Two-color stationary light enables quantum frequency conversion of traveling light pulses at rates approaching unity in theory.
A Simple Ni/Si Schottky Junction Wavelength Sensor for Dual-Wavelength Mixed-Light Color Detection
A silicon Schottky-junction sensor discriminates wavelengths from 365 to 1080 nm and identifies the color of mixed light, linking wavelength directly to color.
Detecting mid-infrared light by molecular frequency upconversion in dual-wavelength nanoantennas
Mid-infrared light around 10 micrometers was converted to visible light via molecular frequency upconversion in plasmonic nanoantennas.